NASA Interface

AGATE data bus specification for

airborne CAN
applications
V 1.7
 Revision history

Ver. Who When What

1.0 M. Stock 10.10.98 Initial Version

1.05 M. Stock 5.11.98 Identifier lists modified
1.1 M. Stock 10.01.99 MIL connector definitions
added
1.2 M. Stock 20.01.99 Navigation identifiers added
1.3 M. Stock 14.04.99 Engine/Fuel system parame-
ter definitions changed, multi-
ple data type support added
1.4 M. Stock 12.07.99 NAV section rearranged, new
data types added
1.5 M. Stock 02.02.00 Connector definitions up-
dated, some data normalized
1.6 M. Stock 13.03.01 Redundancy support and
time triggered bus scheduling
added
1.7 M. Stock 12.01.06 Identifier distribution list
expanded, several node
services added, clarifications

Copyright statement

CANaerospace is an interface standard open to everyone. No copy-

rights are reserved and no licenses are necessary for its implementati-
on, use or distribution. Consequently, the author explicitely refuses
any responsibility arising from the use of this standard in any applicati-
on. This document in its current version is available from:
www.canaerospace.com
Comments to this standard are welcome:
Stock Flight Systems
Schtzenweg 8a
82335 Berg/Farchach
Germany
phone.: +49-8151-9607-0
fax: +49-8151-9607-30
Email: info@stockflightsystems.com

Front cover photograph: NASA test pilot Rogers Smith flying the X-29 research aircraft
over Mojave Desert, California

Revision 1.7, 12.1.2006 1/57 (C) 1998-2006 Stock Flight Systems

 Table of Contents

Section Page

1 Introduction 4
2 Message data types and identifier assignment 4
2.1 Message types 4
2.2 Data types 5
3 Message structure 7
3.1 General message format 8
3.2 Emergency event data (EED) format 9
3.3 Normal operation data (NOD) message format 9
3.4 Node service data (NSH/NSL) message format 9
3.5 Debug service data (DSD) message format 9
3.6 User-defined data (UDH/UDL) message format 9
4 Node service protocol 10
4.1 Identification service (IDS) 13
4.2 Node synchronisation service (HSS) 14
4.3 Data download service (DDS) 15
4.4 Data upload service (DUS) 16
4.5 Simulation control service (SCS) 17
4.6 Transmission interval service (TIS) 17
4.7 FLASH programming service (FPS) 18
4.8 State transmission service (STS) 19
4.9 Filter setting service (FSS) 19
4.10 Test control service (TCS) 19
4.11 Baudrate setting service (BSS) 20
4.12 Node-ID setting service (NIS) 20
4.13 Module information service (MIS) 21
4.14 Module configuration service (MCS) 21
4.15 CAN-ID setting service (CSS) 22
4.16 CAN-ID distribution setting service (DIS) 22
5 CANaerospace default identifier distribution 24
5.1 Flight state/air data 26
5.2 Flight controls data 28
5.3 Aircraft engine/fuel system data 31

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 Table of Contents

Section Page

5.4 Power transmission system data 35

5.5 Hydraulic system data 35
5.6 Electric system data 36
5.7 Navigation system data 36
5.8 Landing gear system data 44
5.9 Miscellaneous data 44
5.10 Reserved data 45
6 Time-triggered bus scheduling 46
6.1 Baseline system 46
6.2 The transmission slot concept 47
6.3 Bus load computation 52
7 System redundancy support 53
7.1 Redundant message identifier assignment 53
7.2 Redundancy and the CANaerospace header 54
8 Physical connector definition 55

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 1 Introduction

CANaerospace is an extremely lightweight protocol/data format defini-

tion which was designed for the highly reliable communication of
microcomputer-based systems in airborne applications via CAN (Con-
troller Area Network). The purpose of this definition is to create a stan-
dard for applications requiring an efficient data flow monitoring and
easy time-frame synchronisation within redundant systems. The defi-
nition is kept widely open to allow implementation of user-defined
message types and protocols. CANaerospace can be used with CAN
2.0A and 2.0B (11-bit and 29-bit identifiers) and any bus data rate.

2 Message/data types and identifier assignment

2.1 Message types The data format definition specifies 6 basic message types, which are
used for different network services. Each message type has an asso-
ciated CAN-ID range defining the message priority. Generally, the
identifier distribution within the specified ranges is at the users discre-
tion. A standard CANaerospace identifier distribution addressing com-
monly used data objects and devices in aerospace applications is
made in section 5, however. The use of this standard distribution sche-
me is highly encouraged for interoperability reasons.

CAN-ID
Message Type Explanation
Range

Emergency 0 - 127 Transmitted asynchronously whe-

Event Data ($000 - $07F) never a situation requiring imme-
(EED) diate action occurs.
High Priority 128 - 199 Transmitted asynchronously or
Node Service ($080 - $0C7) cyclic with defined transmission
Data (NSH) intervals for operational com-
mands (36 channels)
High Priority- 200 - 299 Message/data format and trans-
User-Defined ($0C8 - mission intervals entirely user-de-
Data (UDH) $12B) fined

Normal Opera- 300 - 1799 Transmitted asynchronously or

tion Data ($12C - $707) cyclic with defined transmission
(NOD) intervals for operational and sta-
tus data.
Low Priority- 1800 - 1899 Message/data format and trans-
User-Defined ($708 - $76B) mission intervals entirely user-de-
Data (UDL) fined

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 CAN-ID
Message Type Explanation
Range

Debug 1900 - 1999 Transmitted asynchronously or

Service Data ($76C - cyclic for debug communication &
(DSD) $7CF) software download actions.

Low Priority 2000 - 2031 Transmitted asynchronously or

Node Service $7D0 - $7EF cyclic for test & maintenance ac-
Data (NSL) tions (16 channels).

2.2 Data types For data representation, the most commonly used basic data types
are defined. Additionally, combined data types (i.e. two, three and four
16 bit and 8 bit data types in one CAN message) and aggregate data
types (64-bit double float) are supported. Other data types can be ad-
ded to the type list as required. The type number in the range of 0-255
is used for data type specification as described in section 3.1.

Data Type Range Bits Explanation Type #

NODATA n.a. 0 No data type 0

($00)
ERROR n.a. 32 Emergency event 1
data type ($01)
FLOAT 1-bit sign 32 Single precision 2
23-bit fraction floating-point va- ($02)
8-bit exponent lue according to
IEEE-754-1985
LONG -2147483647 to 32 2s complement 3
+2147483648 integer ($03)
ULONG 0 to 32 unsigned integer 4
4294967295 ($04)
BLONG n.a. 32 Each bit defines a 5
discrete state. 32 ($05)
bits are coded into
four CAN data by-
tes
SHORT -32768 to 16 2s complement 6
+32767 short integer ($06)
USHORT 0 to 65535 16 unsigned short in- 7
teger ($07)

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 Data Type Range Bits Explanation Type #

BSHORT n.a. 16 Each bit defines a 8

discrete state. 16 ($08)
bits are coded into
two CAN data by-
tes
CHAR -128 to +127 8 2s complement 9
char integer ($09)
UCHAR 0 to 255 8 unsigned char in- 10
teger ($0A)
BCHAR n.a. 8 Each bit defines a 11
discrete state. 8 ($0B)
bits are coded into
a single CAN data
byte
SHORT2 -32768 to 2x 2 x 2s comple- 12
+32767 16 ment short integer ($0C)
USHORT2 0 to 65535 2x 2 x unsigned short 13
16 integer ($0D)
BSHORT2 n.a. 2x 2 x discrete short 14
16 ($0E)
CHAR4 -128 to +127 4x 4 x 2s comple- 15
8 ment char integer ($0F)
UCHAR4 0 to 255 4x 4 x unsigned char 16
8 integer ($10)
BCHAR4 n.a. 4x 4 x discrete char 17
8 ($11)
CHAR2 -128 to +127 2x 2 x 2s comple- 18
8 ment char integer ($12)
UCHAR2 0 to 255 2x 2 x unsigned char 19
8 integer ($13)
BCHAR2 n.a. 2x 2 x discrete char 20
8 ($14)
MEMID 0 to 32 Memory ID for 21
4294967295 upload/download ($15)
CHKSUM 0 to 32 Checksum for 22
4294967295 upload/download ($16)
ACHAR 0 to 255 8 ASCII character 23
($17)

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 Data Type Range Bits Explanation Type #

ACHAR2 0 to 255 2x 2 x ASCII 24

8 character ($18)
ACHAR4 0 to 255 4x 4 xASCII 25
8 character ($19)
CHAR3 -128 to +127 3x 3 x 2s comple- 26
8 ment char integer ($1A)
UCHAR3 0 to 255 3x 3 x unsigned char 27
8 integer ($1B)
BCHAR3 n.a. 3x 3 x discrete char 28
8 ($1C)
ACHAR3 0 to 255 3x 4 xASCII 29
8 character ($1D)
DOUBLEH 1-bit sign 32 Most significant 32 30
52-bit fraction bits of double pre- ($1E)
11-bit exponent cision floating-
point value accor-
ding to IEEE-754-
1985
DOUBLEL 1-bit sign 32 Least significant 31
52-bit fraction 32 bits of double ($1F)
11-bit exponent precision floating-
point value accor-
ding to IEEE-754-
1985
RESVD n.a. xx Reserved for fu- 32-99
ture use ($20-
$63)
UDEF n.a. xx User-defined data 100-
types 255
($64-
$FF)

3 Message structure

The coding of the data into the CAN message bytes is according to the
Big Endian definition as used by Motorola 68K, SPARC, PowerPC,
MIPS and other major processor architectures. All CAN messages
consist of 4 header bytes for identification and between 1 and 4 data
bytes for the actual data.

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3.1 General messa- The general message format uses a 4 byte message header for node
ge format identification, data type, message code and service code (for normal
operation data (NOD) , the service code field is user-defined). This al-
lows identification of each message by any receiving unit without the
need for additional information. Every message type uses the same
layout for the CAN data bytes 0-3, while the number and the data type
used for CAN data bytes 4-7 is user-defined:

Message header

Byte 0 Byte 1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6 Byte 7

Message Data (message type specific)

Message Code (UCHAR)
Service Code (xCHAR*)
Data Type (UCHAR)
Node-ID (UCHAR)
*: xCHAR may be CHAR, ACHAR, BCHAR or UCHAR

The header data fields have the following meaning:

The node-ID is in the range of 0-255 with node-ID 0 being
the broadcast-ID referring to all nodes. Note that for emer-
gency event data (EED) and normal operation data (NOD)
messages, the node-ID identifies the transmitting station,
while for node service data (NSH/NSL) messages the node-
ID identifies the addressed station.
The data type specifies the coding of the data transported
with the corresponding message. The number is taken from
the data type list (see section 2.2).
For normal operation data (NOD) messages, the message
code is incremented by one for each message and may be
used to monitor the sequence of incoming messages. The
message code then rolls over to zero after passing 255. This
feature allows any node in the network to determine the age
of a signal and the proper sequence for monitoring purposes.
For node service data (NSL/NSH) messages, however, the
message code is used for extended specification of the ser-
vice.
For normal operation data (NOD) messages, the service
code consists of 8 bits which may be used as required by the
specific data (should be set to zero if unused). For node ser-
vice data (NSL/NSH) messages, the service code contains
the node service code for the current operation.

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3.2 Emergency Event Emergency Event Data (EED) is transmitted asynchronously by the af-
Data (EED) mes- fected unit whenever an error situation occurs. The corresponding
sage format data contains information about the location within the unit at which
the error ocurred, the offending operation and the error code:

Byte 0 Byte 1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6 Byte 7

Message Header Error code (SHORT)

(Byte 1 = $01) OperationID (CHAR)
LocationID (CHAR)

3.3 Normal Operati- Normal Operation Data (NOD) is transmitted during normal operation,
on Data (NOD) either cyclic or asynchronously. The data type (and therefore the mes-
message format sage byte count) is taken from the data type list:

Byte 0 Byte 1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6 Byte 7

Message Header Message data (type/length as required)

3.4 Node Service Node Service Data (NSH/NSL) is data associated to the node service
Data (NSH/NSL) protocol as specified in section 4. The message format is similar to
message format NOD. Node service data, however, is transmitted on specific identi-
fiers only:

Byte 0 Byte 1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6 Byte 7

Message Header Message data (type/length as required)

3.5 Debug Service The Debug Service Data message format is entirely user-defined be-
Data (DSD) mes- cause of the specific requirements resulting from the various host/tar-
sage format get communication protocols. Aside from using the specified identifier
range, no restrictions apply. To maximize flexibility, the message layout
and the data types must not follow any of the CANaerospace definiti-
ons. It is encouraged, however, to use the proposed standard.

3.6 User-Defined User-Defined Data message formats may be created for specific pur-
Data (UDL/UDH) poses. Aside from using the specified identifier range, no restrictions
message format apply. To maximize flexibility, the message layout and the data types
must not follow any of the CANaerospace definitions. It is encouraged,
however, to use the proposed standard.

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 4 Node service protocol

In parallel to the data transfer during normal operation (Emergency

Event Data, Normal Operation Data), the node service protocol provi-
des a connection-oriented communication using a handshake mecha-
nism. This protocol has been implemented to support command/
response type connections between two nodes for specific operations,
i.e. for data download or client/server actions. Note that node service
requests requiring action but no response are possible as well. Re-
quests of this type may be sent to a specific or all nodes (broadcast).
The node service protocol may be run either in high priority or low
priority mode, selected by identifier. For the high priority mode, 36
node service communication channels are available, while the low
priority mode offers 16 communication channels. Each communication
channel consists of one CAN identifier for the node service request
and the immediately following one for the node service response. The
identifier assignment for the high priority node service channels is as
follows:

Node Service Node Service Node Service

Channel Request ID Response ID

0 128 ($080) 129 ($081)

1 130 ($082) 131 ($083)

2 132 ($084) 133 ($085)

....... ....... ......

....... ....... ......

33 194 ($0C2) 195 ($0C3)

34 196 ($0C4) 197 ($0C5)

35 198 ($0C6) 199 ($0C7)

This is the identifier assignment for the low priority node service chan-
nels:

Node Service Node Service Node Service

Channel Request ID Response ID

100 2000 ($7D0) 2001 ($7D1)

101 2002 ($7D2) 2003 ($7D3)

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 Node Service Node Service Node Service
Channel Request ID Response ID

102 2004 ($7D4) 2005 ($7D5)

....... ....... ......

115 2030($7EE) 2031 ($7EF)

A node service is initiated by a node service request message, trans-

mitted on the corresponding identifier. All nodes attached to the net-
work are obliged to continously monitor these identifiers and check if
received messages contain the own personal node-ID. If a match is
detected, the corresponding node has to react by performing the re-
quired action and transmitting a node service response message on
the corresponding identifier within 100ms (if this was required by the
request type). The node service response must again contain the per-
sonal node-ID of the addressed node. Any node in the network is allo-
wed to initiate node services. It is recommended, however, that each
node in the network initiating node service requests uses a dedicated
node service channel to avoid potential hand-shaking conflicts. The
channel on which a particular node service is run may be defined by
the user. If only one service channel is used, node services must be
run on channel 0 by default. Some frequently used types of node ser-
vices are already specified below, other services may be added as re-
quired.
Each CANaerospace unit must support at least the Identification
Service (IDS) on Node Service Channel 0. This makes sure that a
CANaerospace network can be scanned for attached units to de-
termine their status, header type and identifier assignment. Note
that within a CANaerospace network, other header types than the
standard CANaerospace header and several identifier assign-
ment schemes (including entirely user-defined ones) are suppor-
ted. Whenever possible, it is strongly recommended to use the
proposed standard header and identifier assignment, however.

Node Service Response

Action
Service Code Required

IDS 0 Yes Identification service. Requests

a sign-of-life response together
with configuration information
from the addressed node.

NSS 1 No Node synchronisation service,

used to trigger a specific node or
to perform a network wide time
synchronisation.

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 Node Service Response
Action
Service Code Required

DDS 2 Yes Data download service. Sends a

block of data to another node.

DUS 3 Yes Data upload service. Receives a

block of data from another node.

SCS 4 Yes Simulation Control Service. Al-

lows to change the behaviour of
the addressed node by con-
trolling internal simulation soft-
ware functions.

TIS 5 Yes Transmission Interval Service.

Sets the transmission rate of a
specific CAN message transmit-
ted by the addressed node.

FPS 6 Yes FLASH Programming Service.

Triggers a node-internal routine
to store configuration data per-
mantently into non-volatile me-
mory.

STS 7 No State Transmission Service.

Causes the addressed node to
transmit all its CAN messages
once.

FSS 8 Yes Filter Setting Service. Used to

modify the limit frequencies of
node-internal highpass, lowpass
or bandpass filters.

TCS 9 Yes Test Control Service. Triggers in-

ternal test functions of the
addressed node.

BSS 10 No/Yes CAN Baudrate Setting Service.

(result de- Sets the CAN baudrate ot the
pendant) addressed node.

NIS 11 Yes Node-ID Setting Service. Sets

the Node-ID of the addressed
node.

MIS 12 Yes Module Information Service. Ob-

tains information about installed
modules within the addressed
node.

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 Node Service Response
Action
Service Code Required

MCS 13 Yes Module Configuration Service.

Configures installed modules
within the addressed node.

CSS 14 Yes CAN-ID setting service. Sets the

CAN-ID of a specific message
the addressed node transmits.

DSS 15 Yes CAN-ID Distribution Setting Ser-

vice. Sets the identifier distributi-
on code transmitted as Byte 2 of
the response to an IDS request.

XXS 16-99 Reserved for future use.

100- User-defined services.

255

4.1 Identification The identification service is a client/server type service. It is used to

Service (IDS) obtain a sign-of-life indication from the addressed node and check if
its identifier distribution and message header format is compliant with
the network that it is attached to. The addressed node returns a 4 byte
status information which contains information about hardware/soft-
ware revision of the system, together with the identifier distribution and
message header format the node is programmed for. Consequently,
the data type of the response message is UCHAR4.
The term identifier distribution refers to the assignment of CAN iden-
tifiers to physical data objects. This distribution may either be as des-
cribed in section 5 (CANaerospace standard) or of a different type:

Distribution ID (Byte 2
Identifier Distribution
of IDS response)

0 CANaerospace standard

1-99 Reserved for future use

100-255 User-defined distribution schemes

Likewise, a CANaerospace network may choose to deviate from the

standard CANaerospace header format as described in section 3.1. If
this is the case, byte 3 of the message must inform an interrogating
node about this fact by returning a non-zero (user-defined) value in
byte 3 of the IDS response. Note that in this case the IDS service must
still be supported using the CANaerospace standard header format:

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 Message Data Field Service Service
Data Byte Description Request Response

0 Node-ID <node-ID> <node-ID>

1 Data Type NODATA UCHAR4

2 Service 0 0
Code

3 Message <0> <as in request>

Code

4-7 Message n.a. Byte 0: Hardware

Data Revision
Byte 1: Software
Revision
Byte 2: Identifier
Distribution (0 =
CANaerospace
standard distribu-
tion)
Byte 3: Header
Type (0 = CAN-
aerospace stan-
dard header)

4.2 Node Synchroni- The node synchronisation service is a connectionless service (no ser-
sation Service vice response required) used to perform time synchronisation of all
(NSS) nodes attached to the network. Therefore, the node-ID is set to 0. The
time stamp may be used to submit a 32 bit value for clock settings:

Message Data Field Service

Data Byte Description Request

0 Node-ID 0

1 Data type ULONG

2 Service 1
Code

3 Message 0
Code

4-7 Message <time stamp>

Data

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4.3 Data Download The data download is a connection-oriented service and is used to
Service (DDS) send a block of data to another node. The size of the data block may
be in the range of 1-1020 bytes, specified by the message number
field of the header. To initiate the service, the requesting station sends
a start download request message to the addressed node, spe-
cifying a memory destination identifier and the number of messages
which will be transmitted (the data type may change during the down-
load to allow structured data to be sent). It then waits for the response.
If the service response is received within 100ms and the message
data is XON, the requesting station may transmit the specified number
of data messages:

Message Data Field Service Service

Data Byte Description Request Response

0 Node-ID <node-ID> <node-ID>

1 Data Type MEMID LONG

2 Service 2 2
Code

3 Message <0-255> <as in request>

Code

4-7 Message <memory desti- -2 = INVALID

Data nation identifier> -1 = ABORT
0 = XOFF
1 = XON

The addressed node now accepts data until the final message number
has been reached. To control download speed, the addressed node
may send a service response at any time during the download pro-
cess, specifying the current message number and XOFF or XON. By
specifying ABORT or INVALID, the download is cancelled immediately
without further action. The transmitting station has to react correspon-
dingly by stopping or resuming data transmission.
After the last message has been received, the addressed node trans-
mits a service response with a checksum calculated from summing up
all received data. This allows the requesting node to determine if all
data has been received properly:

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 Message Data Field Service Service
Data Byte Description Request Response

0 Node-ID <node-ID> <node-ID>

1 Data type <any> CHKSUM

2 Service 2 2
Code

3 Message <last number> <last number>

Code

4-7 Message <download data> <checksum>

Data

4.4 Data Upload Ser- The data upload is a connection-oriented service and is used to recei-
vice (DUS) ve a block of data from another node. The size of the data block may
be in the range of 1-1020 bytes, specified by the message number
field of the header. To initiate the service, the requesting station sends
a start upload request message to the addressed node, specifying
the source memory identifier and the number of messages which is
expected to be received. It then waits up to 100ms for a service re-
sponse. After having transmitted the service response, the addressed
station waits 10ms and then transmits the requested number of data
messages:

Message Data Field Service Service

Data Byte Description Request Response

0 Node-ID <node-ID> <node-ID>

1 Data Type MEMID LONG

2 Service 3 3
Code

3 Message <0-255> <as in request>

Code

4-7 Message <source memory -1 = ABORT

Data identifier> 0 = OK

The requesting node now accepts data at the maximum transmission

speed until the final message number has been reached. After the last
data message, the addressed node transmits a service response with
a checksum calculated from summing up all transmitted data. This al-
lows the requesting node to determine if all data has been received

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 properly. Additionally, the requesting node continously checks the pro-
per message number sequence during the process to detect failures:

Message Data Field Service

Data Byte Description Response

0 Node-ID <node-ID>

1 Data Type CHKSUM

2 Service 3
Code

3 Message <last number>

Code

4-7 Message <checksum>

Data

4.5 Simulation Con- The simulation control service is a connection-oriented service and is
trol Service used to change the behaviour of the addressed node by controlling in-
(SCS) ternal simulation software functions. Those functions are usually im-
plemented to support the use of the equipment in a simulated
environment where not all external interfaces are available and vary
widely between systems. Consequently, the format of this service is
mostly user-defined:

Message Data Field Service Service

Data Byte Description Request Response

0 Node-ID <node-ID> <node-ID>

1 Data Type <user-defined> <user-defined>

2 Service 4 4
Code

3 Message <user-defined> <user-defined>

Code

4-7 Message <user-defined> <user-defined>

Data

4.6 Transmission In- The transmission interval service is a connection-oriented service and
terval Service is used to set the transmission rate of a specific CAN message trans-
(TIS) mitted by the addressed node. This is accomplished by specifying the
corresponding CAN identifier and the desired transmission rate for this
data in milliseconds. The allowed range for the CAN identifier and the

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 transmission rate is user-defined:

Message Data Field Service Service

Data Byte Description Request Response

0 Node-ID <node-ID> <node-ID>

1 Data Type SHORT2 NODATA

2 Service 5 5
Code

3 Message 0 0 = OK
Code -6 = CAN identi-
fier or transmissi-
on rate out of
range

4-5 Message <CAN identifier> n.a.

Data

6-7 Message <transmission n.a.

Data rate in ms>

4.7 FLASH Pro- The FLASH programming service is a connection-oriented service

gramming Ser- used to store configuration data (i.e. settings made through BSS, NIS,
vice (FPS) CSS or similar services) into internal non-volatile memory. It usually
triggers a node-internal software programming routine. A user-defined
security code (transmitted as the message code) makes sure that this
service can only be issued by authorized nodes in the network:

Message Data Field Service Service

Data Byte Description Request Response

0 Node-ID <node-ID> <node-ID>

1 Data Type NODATA NODATA

2 Service 6 6
Code

3 Message <security code> 0 = OK

Code -3 = invalid secu-
rity code

4-7 Message n.a. n.a.

Data

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4.8 State Transmissi- The state transmission service is a connectionless service which cau-
on Service (STS) ses the addressed node to transmit all its CAN messages once. This
service is used by other nodes in the network which need to to obtain
current data that is normally transmitted upon state change only:

Message Data Field Service

Data Byte Description Request

0 Node-ID <node-ID>

1 Data Type NODATA

2 Service 7
Code

3 Message 0
Code

4-7 Message n.a.

Data

4.9 Filter Setting Ser- The filter setting service is a connection-oriented service used to set
vice (FSS) the limit frequency for node-internal highpass, lowpass or bandpass
filter functions:

Message Data Field Service Service

Data Byte Description Request Response

0 Node-ID <node-ID> <node-ID>

1 Data Type FLOAT NODATA

2 Service 8 8
Code

3 Message <filter number> 0 = OK

Code -6 = limit frequen-
cy or filter number
out of range

4-7 Message <limit frequency> n.a.

Data

4.10 Test Control Ser- The test control is a connection-oriented service and is used to control
vice (TCS) internal test functions of the addressed node. Such functions are
usually implemented to support in-service testing of the equipment
and vary widely between systems. Consequently, the format of this
service is mostly user-defined:

Revision 1.7, 12.1.2006 19/57 (C) 1998-2006 Stock Flight Systems

 Message Data Field Service Service
Data Byte Description Request Response

0 Node-ID <node-ID> <node-ID>

1 Data Type <user-defined> <user-defined>

2 Service 9 9
Code

3 Message <user-defined> <user-defined>

Code

4-7 Message <user-defined> <user-defined>

Data

4.11 Baudrate Setting The baudrate setting service is a (normally) connectionless service
Service (BSS) that modifies the CAN baudrate of the addressed node. The baudrate
change becomes effective immediately and therefore no response to
this service is transmitted in case of success. In case of failure, howe-
ver, the node maintains its original baudrate and returns an error code:

Service
Response
Message Data Field Service
(not transmitted
Data Byte Description Request
when request
was successful)

0 Node-ID <node-ID> <node-ID>

1 Data Type SHORT NODATA

2 Service 10 10
Code

3 Message 0 -1 = baudrate
Code code unknown

4-5 Message <baudrate code> n.a.

Data
0 = 1 MBit/s
1 = 500 kBit/s
2 = 250 kBit/s
3 = 125 kBit/s
....

4.12 Node-ID Setting The Node-ID setting service is a connection-oriented service used to
Service (NIS) set the ID of the addressed node. The new ID becomes effective im-

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 mediately and is used by the affected node a.) to identify itself in the
Node-ID field for all normal operation data (NOD) messages and b.) to
determine if it is addressed by received node service requests:

Message Data Field Service Service

Data Byte Description Request Response

0 Node-ID <node-ID> <node-ID>

1 Data Type NODATA NODATA

2 Service 11 11
Code

3 Message <new node-ID> 0 = OK

Code 1 <= ID <= 199 -6 = node-ID out
of range

4-7 Message n.a. n.a.

Data

4.13 Module Informati- The module information service is a connection-oriented service that
on Service (MIS) returns information about modules installed in the addressed node.
The nature of these modules varies widely between systems. Conse-
quently, the format of this service is mostly user-defined:

Message Data Field Service Service

Data Byte Description Request Response

0 Node-ID <node-ID> <node-ID>

1 Data Type <user-defined> <user-defined>

2 Service 12 12
Code

3 Message <user-defined> <user-defined>

Code

4-7 Message <user-defined> <user-defined>

Data

4.14 Module Configu- The module configuration service is a connection-oriented service that
ration Service configures modules installed in the addressed node. The nature of
(MCS) these modules varies widely between systems. Consequently, the
format of this service is mostly user-defined:

Revision 1.7, 12.1.2006 21/57 (C) 1998-2006 Stock Flight Systems

 Message Data Field Service Service
Data Byte Description Request Response

0 Node-ID <node-ID> <node-ID>

1 Data Type <user-defined> <user-defined>

2 Service 13 13
Code

3 Message <user-defined> <user-defined>

Code

4-7 Message <user-defined> <user-defined>

Data

4.15 CAN Identifier The CAN identifier setting service is a connection-oriented service
Setting Service used to set the CAN identifier of a specific CAN message transmitted
(CSS) by the addressed node. This is accomplished by specifying the mes-
sage through a unique message number together with the desired
CAN identifier for this message. The allowed range for the message
number and the CAN identifier is user-defined:

Message Data Field Service Service

Data Byte Description Request Response

0 Node-ID <node-ID> <node-ID>

1 Data Type SHORT2 NODATA

2 Service 14 14
Code

3 Message 0 0 = OK
Code -6 = message
number or CAN
identifier out of
range

4-5 Message <message num- n.a.

Data ber>

6-7 Message <CAN identifier> n.a.

Data

4.16 CANaerospace The CANaerospace identifier distribution setting service is a connec-

Identifier Distri- tion-oriented service used to set the identifier distribution ID of the
bution Setting addressed node. The new distribution ID becomes effective immedia-
Service (DSS) tely and will be returned by the affected node in byte 2 of the response

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 to an identification service (IDS) request:

Message Data Field Service Service

Data Byte Description Request Response

0 Node-ID <node-ID> <node-ID>

1 Data Type NODATA NODATA

2 Service 15 15
Code

3 Message <new distribution 0 = OK

Code ID> -6 = distribution
0<= ID <= 240 ID out of range

4-7 Message n.a. n.a.

Data

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 5 CANaerospace default identifier distribution

In addition to basic message formats and the node service protocol,

CANaerospace defines an identifier distribution (also referred to as a
profile) as a means to effectively support interoperability between no-
des. Together with the self-identifying message format and the time-
triggered bus scheduling, this concept makes sure that nodes desi-
gned by different vendors may be integrated into an already existing
CANaerospace network quickly and with minimum effort.
By default, an identifier distribution scheme addressing the most com-
monly used data for aerospace applications has been specified. For
this purpose, the available identifiers for normal operation data have
been grouped for the various aircraft systems, thereby reserving the
identifier range 300-1499. The identifiers from 1500-1799 are unassi-
gned and may be used for other data at the users discretion.
Note that other identifier distribution schemes besides this de-
fault one may be developed and will eventually be added in future
releases of the CANaerospace specification. Likewise, user-defi-
ned identifier distribution schemes, derived from the default, or
with entirely different content are supported by CANaerospace. It
is therefore extremely important that every node provides infor-
mation about the identifier distribution it uses in response to an
identification (IDS) node service request. This allows any node in
the network to interrogate the entire range of node-IDs (1 to 255)
and determine if its own identifier distribution scheme is compa-
tible with the one used in the network.
Parameters may support several data types if indicated in the sugge-
sted data types field. If this is the case, the user may select the appro-
priate type with respect to system requirements, processor
performance, etc. If analogue parameters are transmitted as SHORT2
using this identifier distribution, the first SHORT variable contains the
current value, while the second SHORT variable contains the maxi-
mum value of this parameter (to support parameter scaling for the re-
ceiving nodes) as described in the following example:
SensorValue = AnalogValue/(32767/AnalogScale)

Example: AnalogFactor
EGT range: 0-1500K
AnalogScale = 1500 ($05DC)
AnalogFactor = 32767/1500 = 21.84
AnalogValue = 16384 ($4000)
SensorValue = 16384/21.84 = 750K

$7C $0C $00 $4A $40 $00 $05 $DC

Message Header AnalogValue AnalogScale

(variable) (constant)

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 The data units are SI units according to ISO 1000 with some excepti-
ons (hPa, deg/s). All data referring to aircraft axis systems are based
on ISO 1151-1 and ISO 1151-2 (equivalent to LN9300) as shown in
the picture below:

airflow

Symbol Definition

xf, yf, zf Body axis system

xa, ya, za Airpath axis system

xe, ye, ze Intermediate axis system

V Velocity vector

A Lift vector

Qe Transverse force vector

We Drag vector

Angle of attack

Angle of sideslip

These axis systems define the signs used for flight state data. The
signs used for the cockpit flight controls are not specified in ISO 1151
and therefore defined according to international conventions.

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5.1 Flight state/air
data CAN Flight state Suggested
Units Notes
identifier parameter name data types

300 Body longitudinal FLOAT g forward: +

($12C) acceleration SHORT2 aft: -

301 Body lateral FLOAT g right: +

($12D) acceleration SHORT2 left: -

302 Body normal FLOAT g up: +

($12E) acceleration SHORT2 down: -

303 Body pitch rate FLOAT deg/s nose up: +

($12F) SHORT2 nose down: -

304 Body roll rate FLOAT deg/s roll right: +

($130) SHORT2 roll left: -

305 Body yaw rate FLOAT deg/s yaw right: +

($131) SHORT2 yaw left: -

306 Rudder position FLOAT deg. clockwise

($132) SHORT2 deflection: +
counterclock-
wise
deflection: -

307 Stabilizer position FLOAT deg. deflection

($133) SHORT2 downward: +
deflection
upward: -

308 Elevator position FLOAT deg. deflection

($134) SHORT2 downward: +
deflection
upward: -

309 Left aileron position FLOAT deg. deflection

($135) SHORT2 downward: +
deflection
upward: -

310 Right aileron FLOAT deg. deflection

($136) position SHORT2 downward: +
deflection
upward: -

311 Body pitch angle FLOAT deg. nose up: +

($137) SHORT2 nose down: -

312 Body roll angle FLOAT deg. roll right: +

($138) SHORT2 roll left: -

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 CAN Flight state Suggested
Units Notes
identifier parameter name data types

313 Body sideslip FLOAT deg. yaw right: +

($139) SHORT2 yaw left: -

314 Altitude rate FLOAT m/s

($13A) SHORT2

315 Indicated airspeed FLOAT m/s

($13B) SHORT2

316 True airspeed FLOAT m/s

($13C) SHORT2

317 Calibrated airspeed FLOAT m/s

($13D) SHORT2

318 Mach number FLOAT Mach

($13E) SHORT2

319 Baro Correction FLOAT hPa

($13F) SHORT2

320 Baro corrected FLOAT m

($140) altitude SHORT2

321 Heading angle FLOAT deg +/- 180o

($141) SHORT2

322 Standard altitude FLOAT m

($142) SHORT2

323 Total air temperature FLOAT K

($143) SHORT2

324 Static air FLOAT K

($144) temperature SHORT2

325 Differential pressure FLOAT hPa

($145) SHORT2

326 Static pressure FLOAT hPa

($146) SHORT2

327 Heading rate FLOAT deg/s

($147) SHORT2

328 Port side angle-of- FLOAT deg nose up: +

($148) attack (AOA) SHORT2 nose down: -

329 Starbord side angle- FLOAT deg nose up: +

($149) of-attack (AOA) SHORT2 nose down: -

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 CAN Flight state Suggested
Units Notes
identifier parameter name data types

330 Density altitude FLOAT m

($14A) SHORT2

331 Turn coordination FLOAT deg/s

($14B) rate SHORT2

332 True altitude FLOAT m

($14C) SHORT2

333 Wind speed FLOAT m/s

($14D) SHORT2

334 Wind direction FLOAT deg +/- 180o

($14E) SHORT2

335 Outside air FLOAT K

($14F) temperature (OAT) SHORT2

336 Body normal FLOAT m/s

($150) velocity SHORT2

337 Body longitudinal FLOAT m/s

($151) velocity SHORT2

338 Body lateral FLOAT m/s

($152) velocity SHORT2

339 Total pressure FLOAT hPa

($153) SHORT2

5.2 Flight controls The flight controls section also contains aircraft engine controls. This
data data is divided into sections A and B to support dual redundant engine
control systems (ECS). All engine data is available with two different
CAN identifiers so that it may be transmitted on the same bus without
interference.
In case this feature is not used, ECS channel A may also be interpre-
ted as starboard engines and ECS channel B as port engines so
that in total, up to eight engines per aircraft may be supported.

CAN Flight controls Suggested

Units Notes
identifier parameter name data types

400 Pitch control position FLOAT Norm aft: +

($190) SHORT2 -1/+1 forward: -

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 CAN Flight controls Suggested
Units Notes
identifier parameter name data types

401 Roll control position FLOAT Norm right: +

($191) SHORT2 -1/+1 left: -

402 Lateral stick trim po- FLOAT Norm right: +

($192) sition command SHORT2 -1/+1 left: -

403 Yaw control position FLOAT Norm left pedal: -

($193) SHORT2 -1/+1 right pedal: +

404 Collective control FLOAT Norm down: -

($194) position SHORT2 -1/+1 up: +

405 Longitudinal stick FLOAT Norm aft: +

($195) trim position com- SHORT2 -1/+1 forward: -
mand

406 Directional pedals FLOAT Norm left pedal: -

($196) trim position com- SHORT2 -1/+1 right pedal: +
mand

407 Collective lever trim FLOAT Norm down: -

($197) position command SHORT2 -1/+1 up: +

408 Cyclic control stick BLONG

($198) switches BSHORT

409 Lateral trim speed FLOAT Norm

($199) SHORT2 -1/+1

410 Longitudinal trim FLOAT Norm

($19A) speed SHORT2 -1/+1

411 Pedal trim speed FLOAT Norm

($19B) SHORT2 -1/+1

412 Collective trim speed FLOAT Norm

($19C) SHORT2 -1/+1

413 Nose wheel stee- FLOAT Norm right: +

($19D) ring handle position SHORT2 -1/+1 left: -

414 - Engine #n throttle le- FLOAT Norm

417 ver position SHORT2 -1/+1
($19E - (1 <= n <= 4)
$1A1) ECS channel A

418 - Engine #n condition FLOAT Norm

421 lever position SHORT2 -1/+1
($1A2 - (1 <= n <= 4)
$1A5) ECS channel A

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 CAN Flight controls Suggested
Units Notes
identifier parameter name data types

422 - Engine #n throttle le- FLOAT Norm

425 ver position SHORT2 -1/+1
($1A6 - (1 <= n <= 4)
$1A9) ECS channel B

426 - Engine #n condition FLOAT Norm

429 lever position SHORT2 -1/+1
($1AA - (1 <= n <= 4)
$1AD) ECS channel B

430 Flaps lever position FLOAT Norm

($1AE) SHORT2 -1/+1

431 Slats lever position FLOAT Norm

($1AF) SHORT2 -1/+1

432 Park brake lever po- FLOAT Norm

($1B0) sition SHORT2 -1/+1

433 Speedbrake lever FLOAT Norm

($1B1) position SHORT2 -1/+1

434 Throttle max lever FLOAT Norm

($1B2) position SHORT2 -1/+1

435 Pilot left brake pedal FLOAT Norm

($1B3) position SHORT2 -1/+1

436 Pilot right brake pe- FLOAT Norm

($1B4) dal position SHORT2 -1/+1

437 Copilot left brake pe- FLOAT Norm

($1B5) dal position SHORT2 -1/+1

438 Copilot right brake FLOAT Norm

($1B6) pedal position SHORT2 -1/+1

439 Trim system BLONG

($1B7) switches BSHORT

440 Trim system lights BLONG

($1B8) BSHORT

441 Collective control BLONG helicopters

($1B9) stick switches BSHORT only

442 Stick shaker stall BLONG

($1BA) warning device BSHORT

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 Aircraft engine data is divided into sections A and B to support dual
5.3 Aircraft engine/
redundant engine control systems (ECS). All engine data is available
fuel supply sy-
with two different CAN identifiers so that it may be transmitted on the
stem data
same bus without interference.
In case this feature is not used, ECS channel A may also be interpre-
ted as starboard engines and ECS channel B as port engines so
that in total, up to eight engines per aircraft can be supported.

CAN Engine parameter Suggested

Units Notes
identifier name data types

500 - Engine #n N1 FLOAT 1/min N1 for jet engi-

503 (1 <= n <= 4) SHORT2 nes, cranks-
($1F4 - ECS channel A haft RPM for
$1F7) piston engines

504 - Engine #n N2 FLOAT 1/min N2 for jet engi-

507 (1 <= n <= 4) SHORT2 nes, propeller
($1F8 - ECS channel A RPM for pi-
$1FB) ston engines

508 - Engine #n torque FLOAT Norm

511 (1 <= n <= 4) SHORT2 -1/+1
($1FC - ECS channel A
$1FF)

512 - Engine #n turbine in- FLOAT K TIT

515 let temperature SHORT2
($200 - (1 <= n <= 4)
$203 ECS channel A

516 - Engine #n interturbi- FLOAT K ITT

519 ne temperature SHORT2
($204 - (1 <= n <= 4)
$207) ECS channel A

520 - Engine #n turbine FLOAT K TOT

523 outlet temperature SHORT2
($208 - (1 <= n <= 4)
$20B) ECS channel A

524 - Engine #n fuel flow FLOAT l/h

527 rate SHORT2
($20C - (1 <= n <= 4)
$20F) ECS channel A

528 - Engine #n manifold FLOAT hPa piston engi-

531 pressure SHORT2 nes only
($210 - (1 <= n <= 4)
$213) ECS channel A

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 CAN Engine parameter Suggested
Units Notes
identifier name data types

532 - Engine #n oil FLOAT hPa

535 pressure SHORT2
($214 - (1 <= n <= 4)
$217) ECS channel A

536 - Engine #n oil FLOAT K

539 temperature SHORT2
($218 - (1 <= n <= 4)
$21B) ECS channel A

540 - Engine #n cylinder FLOAT K piston engi-

543 head temperature SHORT2 nes only
($21C - (1 <= n <= 4)
$21F) ECS channel A

544 - Engine #n oil FLOAT l

547 quantity SHORT2
($220 - (1 <= n <= 4)
$223) ECS channel A

548 - Engine #n cooland FLOAT K

551 temperature SHORT2
($224 - (1 <= n <= 4)
$227) ECS channel A

552 - Engine #n power FLOAT Norm

555 rating SHORT2 -1/+1
($228 - (1 <= n <= 4)
$22B) ECS channel A

556 - Engine #n Status 1 BSHORT bit encoding

559 (1 <= n <= 4) BLONG user defined
($22C - ECS channel A
$22F)

560 - Engine #n Status 2 BSHORT bit encoding

563 (1 <= n <= 4) BLONG user defined
($230 - ECS channel A
$233)

564 - Engine #n N1 FLOAT 1/min N1 for jet engi-

567 (1 <= n <= 4) SHORT2 nes, cranks-
($234 - ECS channel B haft RPM for
$237) piston engines

568 - Engine #n N2 FLOAT 1/min N2 for jet engi-

571 (1 <= n <= 4) SHORT2 nes, propeller
($238 - ECS channel B RPM for pi-
$23B ston engines

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 CAN Engine parameter Suggested
Units Notes
identifier name data types

572 - Engine #n torque FLOAT Norm

575 (1 <= n <= 4) SHORT2 -1/+1
($23C - ECS channel B
$23F)

576 - Engine #n turbine in- FLOAT K TIT

579 let temperature SHORT2
($240 - (1 <= n <= 4)
$243) ECS channel B

580 - Engine #n interturbi- FLOAT K ITT

583 ne temperature SHORT2
($244 - (1 <= n <= 4)
$247) ECS channel B

584 - Engine #n turbine FLOAT K TOT for jet en-

587 outlet temperature SHORT2 gines, exhaust
($248 - (1 <= n <= 4) gas tempera-
$24B) ECS channel B ture for piston
engines

588 - Engine #n fuel flow FLOAT l/h

591 rate SHORT2
($24C - (1 <= n <= 4)
$24F) ECS channel B

592 - Engine #n manifold FLOAT hPa piston engi-

595 pressure SHORT2 nes only
($250 - (1 <= n <= 4)
$253) ECS channel B

596 - Engine #n oil FLOAT hPa

599 pressure SHORT2
($254 - (1 <= n <= 4)
$257) ECS channel B

600 - Engine #n oil FLOAT K

603 temperature SHORT2
($258 - (1 <= n <= 4)
$25B) ECS channel B

604 - Engine #n cylinder FLOAT K piston

607 head temperature SHORT2 engines only
($25C - (1 <= n <= 4)
$25F) ECS channel B

608 - Engine #n oil FLOAT l

611 quantity SHORT2
($260 - (1 <= n <= 4)
$263) ECS channel B

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 CAN Engine parameter Suggested
Units Notes
identifier name data types

612 - Engine #n coolant FLOAT K

615 temperature SHORT2
($264 - (1 <= n <= 4)
$267) ECS channel B

616 - Engine #n power FLOAT Norm

619 rating SHORT2 -1/+1
($268 - (1 <= n <= 4)
$26B) ECS channel B

620 - Engine #n Status 1 BSHORT bit encoding

623 (1 <= n <= 4) BLONG user defined
($26C - ECS channel B
$26F)

624 - Engine #n Status 2 BSHORT bit encoding

627 (1 <= n <= 4) BLONG user defined
($270 - ECS channel B
$273)

628 - Reserved for future

659 use
($274 -
$293)

660 - Fuel pump #n flow FLOAT l/h

667 rate SHORT2
($294 - (1 <= n <= 8)
$29B)

668 - Fuel tank #n quantity FLOAT kg

675 (1 <= n <= 8) SHORT2
($29C -
$2A3)

676 - Fuel tank #n tempe- FLOAT K

683 rature SHORT2
($2A4 - (1 <= n <= 8)
$2AB)

684 - Fuel system #n FLOAT hPa

691 pressure SHORT2
($2AC - (1 <= n <= 8)
$2B3)

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5.4 Power transmis-
sion system data Transmission
CAN Suggested
system Units Notes
identifier data types
parameter name

700 - Rotor #n RPM FLOAT 1/min helicopters

703 (1 <= n <= 4) SHORT2 only
($2BC -
$2C0)

704 - Gearbox #n speed FLOAT 1/min

711 (1 <= n <= 8) SHORT2
($2BD -
$2C7)

712 - Gearbox #n oil FLOAT hPa

719 pressure SHORT2
($2BC - (1 <= n <= 8)
$2CF)

720 - Gearbox #n oil FLOAT K

727 temperature SHORT2
($2D0 - (1 <= n <= 8)
$2D7)

728 - Gearbox #n oil FLOAT l

735 quantity SHORT2
($2D8 - (1 <= n <= 8)
$2DF)

5.5 Hydraulic system

data
CAN Hydraulic system Suggested
Units Notes
identifier parameter name data types

800 - Hydraulic system #n FLOAT hPa

807 pressure SHORT2
($320 - (1 <= n <= 8)
$327)

808 - Hydraulic system #n FLOAT K

815 fluid temperature SHORT2
($328 - (1 <= n <= 8)
$32F)

816 - Hydraulic system #n FLOAT l

823 fluid quantity SHORT2
($330 - (1 <= n <= 8)
$337)

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5.6 Electric system
data CAN Electric system Suggested
Units Notes
identifier parameter name data types

900 - AC system #n FLOAT volt

909 voltage SHORT2
($384 - (1 <= n <= 10)
$38D)

910 - AC system #n FLOAT am-

919 current SHORT2 pere
($38E - (1 <= n <= 10)
$397)

920 - DC system #n FLOAT volt

929 voltage SHORT2
($398 - (1 <= n <= 10)
$3A1)

930 - DC system #n FLOAT am-

939 current SHORT2 pere
($3A2 - (1 <= n <= 10)
$3AB)

940 - Prop #n iceguard FLOAT am-

949 DC current SHORT2 pere
($3AC - (1 <= n <= 10)
$3B5)

5.7 Navigation system

data
CAN Navigation system Suggested
Units Notes
identifier parameter name data types

1000 Active nav system FLOAT deg service code

($3E8) waypoint latitude SHORT2 field contains
waypoint #

1001 Active nav system FLOAT deg service code

($3E9) waypoint longitude SHORT field contains
waypoint #

1002 Active nav system FLOAT m service code

($3EA) waypoint height SHORT2 field contains
above ellipsoid waypoint #

1003 Active nav system FLOAT m service code

($3EB) waypoint altitude SHORT2 field contains
waypoint #

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 CAN Navigation system Suggested
Units Notes
identifier parameter name data types

1004 Active nav system FLOAT m/s service code

($3EC) ground speed (GS) SHORT2 field contains
waypoint #

1005 Active nav system FLOAT deg service code

($3ED) true track (TT) SHORT2 field contains
waypoint #

1006 Active nav system FLOAT deg service code

($3EE) magnetic track (MT) SHORT2 field contains
waypoint #

1007 Active nav system FLOAT m service code

($3EF) cross track error SHORT2 field contains
(XTK) waypoint #

1008 Active nav system FLOAT deg service code

($3F0) track error angle SHORT2 field contains
(TKE) waypoint #

1009 Active nav system SHORT min service code

($3F1) time-to-go field contains
waypoint #

1010 Active nav system SHORT min service code

($3F2) estimated time of field contains
arrival (ETA) waypoint #

1011 Active nav system SHORT min service code

($3F3) estimated enroute field contains
time (ETE) waypoint #

1012 NAV waypoint ACHAR4 service code

($3F4) identifier field contains
(char 0-3) waypoint #

1013 NAV waypoint ACHAR4 service code

($3F5) identifier field contains
(char 4-7) waypoint #

1014 NAV waypoint ACHAR4 service code

($3F6) identifier field contains
(char 8-11) waypoint #

1015 NAV waypoint ACHAR4 service code

($3F7) identifier field contains
(char 12-15) waypoint #

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 CAN Navigation system Suggested
Units Notes
identifier parameter name data types

1016 NAV waypoint LONG service code

($3F8) type identifier SHORT field contains
waypoint #

1017 NAV waypoint FLOAT deg service code

($3F9) latitude SHORT2 field contains
waypoint #

1018 NAV waypoint FLOAT deg service code

($3FA) longitude SHORT2 field contains
waypoint #

1019 NAV waypoint FLOAT m service code

($3FB) minimum altitude SHORT2 field contains
waypoint #

1020 NAV waypoint FLOAT m service code

($3FC) minimum flight level SHORT2 field contains
waypoint #

1021 NAV waypoint FLOAT m service code

($3FD) minimum radar SHORT2 field contains
height waypoint #

1022 NAV waypoint FLOAT m service code

($3FE) minimum height SHORT2 field contains
above ellipsoid waypoint #

1023 NAV waypoint FLOAT m service code

($3FF) maximum altitude SHORT2 field contains
waypoint #

1024 NAV waypoint FLOAT m service code

($400) maximum flight level SHORT2 field contains
waypoint #

1025 NAV waypoint FLOAT m service code

($401) maximum radar SHORT2 field contains
height waypoint #

1026 NAV waypoint FLOAT m service code

($402) maximum height SHORT2 field contains
above ellipsoid waypoint #

1027 NAV waypoint FLOAT m service code

($403) planned altitude SHORT2 field contains
waypoint #

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 CAN Navigation system Suggested
Units Notes
identifier parameter name data types

1028 NAV waypoint FLOAT m service code

($404) planned flight level SHORT2 field contains
waypoint #

1029 NAV waypoint FLOAT m service code

($405) planned radar height SHORT2 field contains
waypoint #

1030 NAV waypoint FLOAT m service code

($406) planned height SHORT2 field contains
above ellipsoid waypoint #

1031 Distance to FLOAT m service code

($407) NAV waypoint SHORT2 field contains
waypoint #

1032 Time-to-go to SHORT min service code

($408) NAV waypoint field contains
waypoint #

1033 NAV waypoint SHORT min service code

($409) estimated time of field contains
arrival (ETA) waypoint #

1034 NAV waypoint SHORT min service code

($40A) estimated enroute field contains
time (ETE) waypoint #

1035 NAV waypoint BLONG service code

($40B) status information BSHORT field contains
waypoint #

1036 GPS aircraft DOUBLEL/ deg

($40C) latitude DOUBLEH
FLOAT
SHORT2

1037 GPS aircraft DOUBLEL/ deg

($40D) longitude DOUBLEH
FLOAT
SHORT

1038 GPS aircraft height FLOAT m

($40E) above ellipsoid SHORT2

1039 GPS ground speed FLOAT m/s

($40F) (GS) SHORT2

1040 GPS true track (TT) FLOAT deg

($410) SHORT2

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 CAN Navigation system Suggested
Units Notes
identifier parameter name data types

1041 GPS magnetic track FLOAT deg

($411) (MT) SHORT2

1042 GPS cross track FLOAT m

($412) error (XTK) SHORT2

1043 GPS track error FLOAT deg

($413) angle (TKE) SHORT2

1044 GPS glideslope FLOAT m

($414) deviation SHORT2

1045 GPS predicted ULONG

($415) RAIM USHORT

1046 GPS vertical figure FLOAT m

($416) of merit SHORT2

1047 GPS horizontal FLOAT m

($417) figure of merit SHORT2

1048 GPS mode of SHORT

($418) operation

1049 INS aircraft latitude FLOAT deg

($419) SHORT2

1050 INS aircraft FLOAT deg

($41A) longitude SHORT

1051 INS aircraft height FLOAT m

($41B) above ellipsoid SHORT2

1052 INS aircraft ground FLOAT m/s

($41C) speed (GS) SHORT2

1053 INS aircraft true FLOAT deg

($41D) track (TT) SHORT2

1054 INS aircraft FLOAT deg

($41E) magnetic track (MT) SHORT2

1055 INS aircraft cross FLOAT m

($41F) track error (XTK) SHORT2

1056 INS aircraft track FLOAT deg

($420) error angle (TKE) SHORT2

1057 INS vertical figure of FLOAT m

($421) merit SHORT2

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 CAN Navigation system Suggested
Units Notes
identifier parameter name data types

1058 INS horizontal FLOAT m

($422) figure of merit SHORT2

1059 Auxiliary nav FLOAT deg

($423) system aircraft SHORT2
latitude

1060 Auxiliary nav FLOAT deg

($424) system aircraft SHORT
longitude

1061 Auxiliary nav FLOAT m

($425) system aircraft SHORT2
height above
ellipsoid

1062 Auxiliary nav FLOAT m/s

($426) system aircraft SHORT2
ground speed (GS)

1063 Auxiliary nav FLOAT deg

($427) system aircraft true SHORT2
track (TT)

1064 Auxiliary nav FLOAT deg

($428) system aircraft SHORT2
magnetic track (MT)

1065 Auxiliary nav FLOAT m

($429) system aircraft cross SHORT2
track error (XTK)

1066 Auxiliary nav FLOAT deg

($42A) system aircraft track SHORT2
error angle (TKE)

1067 Auxiliary nav FLOAT m

($42B) system vertical figu- SHORT2
re of merit

1068 Auxiliary nav FLOAT m

($42C) system horizontal SHORT2
figure of merit

1069 Magnetic heading FLOAT deg

($42D) (MH) SHORT2

1070 Radio Height FLOAT m

($42E) SHORT2

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 CAN Navigation system Suggested
Units Notes
identifier parameter name data types

1071 - DME #n distance FLOAT m

1074 (1 < n <= 4) SHORT2
($42F -
$432)

1075 - DME #n time-to-go SHORT min

1078 (1 < n <= 4)
($433 -
$436)

1079 - DME #n FLOAT m/s

1082 ground speed SHORT2
($437 - (1 < n <= 4)
$43A)

1083 - ADF #n bearing FLOAT deg

1086 (1 < n <= 4) SHORT2
($43B -
$43E)

1087 - ILS #n localize FLOAT deg

1090 deviation SHORT2
($43F - (1 < n <= 4)
$442)

1091 - ILS #n glideslope FLOAT deg

1094 deviation SHORT2
($443 - (1 < n <= 4)
$446)

1095 - Flight director #n FLOAT deg

1096 pitch deviation SHORT2
($446 - (1 < n <= 2)
$447)

1097 - Flight director #n FLOAT deg

1098 roll deviation SHORT2
($448 - (1 < n <= 2)
$449)

1099 Decision height FLOAT m

($44A) SHORT2

1100 - VHF #n COM FLOAT MHz

1103 frequency ACHAR4
($44B - (0 < n < 4)
$44F)

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 CAN Navigation system Suggested
Units Notes
identifier parameter name data types

1104 - VOR/ILS #n FLOAT MHz

1107 frequency ACHAR4
($450 - (1 < n <= 4)
$453)

1108 - ADF #n frequency FLOAT KHz

1111 (1 < n <= 4) ACHAR4
($454 -
$457)

1112 - DME #n channel FLOAT

1115 (1 < n <= 4) ACHAR4
($458 -
$45B)

1116 - Transponder #n FLOAT

1119 code ACHAR4
($45C - (1 < n <= 4)
$45F)

1120 Desired track angle FLOAT deg

($460) SHORT2

1121 Magnetic variation FLOAT deg

($461) SHORT2

1122 Selected glidepath FLOAT deg

($462) angle SHORT2

1123 Selected runway FLOAT deg

($463) heading SHORT2

1124 Computed vertical FLOAT m/s

($464) velocity SHORT2

1125 Selected course FLOAT deg

($465) SHORT2

1126 - VOR #n radial FLOAT deg

1129 (1 < n <= 4) SHORT2
($466 -
$469)

1130 True east velocity FLOAT m/s

($46A) SHORT2

1131 True north velocity FLOAT m/s

($46B) SHORT2

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 CAN Navigation system Suggested
Units Notes
identifier parameter name data types

1132 True up velocity FLOAT m/s

($46C) SHORT2

1133 true heading FLOAT deg +/- 180o

($46D) SHORT2

5.8 Landing gear

system data
Landing gear
CAN Suggested
system Units Notes
identifier data types
parameter name

1175 Gear lever switches BLONG

($497) BSHORT

1176 Gear lever lights/ BLONG

($498) WOW solenoid BSHORT

1177 - Landing gear #n tire FLOAT hPa service code

1180 pressure SHORT2 field contains
($499 - (1 < n <= 4) tire number
$49C)

1181 - Landing gear #n bra- FLOAT mm service code

1184 ke pad thickness SHORT2 field contains
($49D - (1 < n <= 4) brake pad
$4A0) number

5.9 Miscellaneous
data
CAN Miscellaneous Suggested
Units Notes
identifier parameter name data types

1200 UTC CHAR4 format:

($4B0) 13h43min22s
13 43 22 00

1201 Cabin pressure FLOAT hPa

($4B1) SHORT2

1202 Cabin altitude FLOAT m

($4B2) SHORT2

1203 Cabin temperature FLOAT K

($4B3) SHORT2

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 CAN Miscellaneous Suggested
Units Notes
identifier parameter name data types

1204 Longitudinal center FLOAT %

($4B4) of gravity SHORT2 MAC

1205 Lateral center of FLOAT %

($4B5) gravity SHORT2 MAC

1206 Date CHAR4 format:

($4B6) 12. June 1987
12 06 19 87

5.10 Reserved data

CAN Suggested
Parameter name Units Notes
identifier data types

1300 - Reserved for future

1499 use
($514 -
$577)

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 6 Time-Triggered Bus Scheduling

This section describes a sample avionics system for a general aviation

aircraft and the resulting CANaerospace bus implementation.
The purpose of this example is to serve as a guideline for the evaluati-
on of system requirements, CANaerospace bus load and transmission
rates based on the basic systems installed in modern technology ge-
neral aviation aircraft.

6.1 Baseline system The baseline system reflects the avionic system as installed in a IFR-
equipped single engine general aviation aircraft using flat panel prima-
ry flight and navigation displays. This architecture was chosen as it
can potentially support highway in the sky (HITS) technology. Even
though it was kept rather simple, however, to better serve its purpose
as explanatory example:

CANaerospace
System Description
Node-ID

1 Attitude/heading reference system (AHRS)

2 Air data computer (ADC)
3 VHF communication transceiver #1
4 VHF communication transceiver #2
5 NAV/ILS/Marker receiver #1
6 NAV/ILS/Marker receiver #2
7 ATC transponder
8 ADF receiver
9 GPS receiver
10 Distance measuring equipment (DME)
11 Engine monitoring system (EMS)
12 Electrical trim system
13 Electric system

To determine the CANaerospace bus schedule, it will be assumed that

the maximum transfer rate of parameters is 80Hz (12.5ms). We could
transmit data at a much higher rate but this would make no sense un-
less there is equipment installed which can make use of this.

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6.2 The transmission The concept of the time-triggered bus scheduling uses a minor time
slot concept frame (12.5ms in our case) and takes advantage of the fact that not
all messages in a given system have to be transmitted at this interval.
Specifying multiples of the minor time frame transmission interval and
associated transmission slots allow a substantially larger number of
parameters to be transmitted on a single bus:

Number of
Parameters/ Transmission
Transmission Transmission
Transmission Slot
interval Slots (equalling
Slot Identification
100% bus load)

12.5ms 1 100 A0 - A99

(80Hz)
25ms 2 200 B0[0] - B99[1]
(40Hz)
50ms 4 400 C0[0] - C99[3]
(20Hz)
100ms 8 800 D0[0] - D99[7]
(10Hz)
200ms 16 1600 E0[0] - E99[15]
(50Hz)
400ms 32 3200 F0[0] - F99[31]
(2.5Hz)
1000ms 80 8000 G0[0] - G99[79]
(1.0Hz)

With this transmission slot concept, either 100 parameters transmitted

each 12.5ms or 8000 parameters transmitted once a second would
generate 100% bus load. More likely, however, a combination of para-
meters in the various transmission slot groups from this table (A-G)
will be used. For our baseline system, we identified the following data
and assigned them the transmission slot groups A,D and G:

Trans-
Tx Data
Parameter Name Unit mission CAN-ID
Slot Type
Interval

A0 Body longitudinal g 12.5ms 300 FLOAT

acceleration ($12C)

A1 Body lateral g 12.5ms 301 FLOAT

acceleration ($12D)

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 Trans-
Tx Data
Parameter Name Unit mission CAN-ID
Slot Type
Interval

A2 Body normal g 12.5ms 302 FLOAT

acceleration ($12E)

A3 Body pitch rate deg/s 12.5ms 303 FLOAT

($12F)

A4 Body roll rate deg/s 12.5ms 304 FLOAT

($130)

A5 Body yaw rate deg/s 12.5ms 305 FLOAT

($131)

A6 Body pitch angle deg 12.5ms 311 FLOAT

($137)

A7 Body roll angle deg 12.5ms 312 FLOAT

($138)

A8 Heading angle deg 12.5ms 321 FLOAT

($141)

D0[0] Altitude rate m/s 100ms 314 FLOAT

($13A)

D0[1] True airspeed m/s 100ms 316 FLOAT

($13C)

D0[2] Computed (calibrated) m/s 100ms 317 FLOAT

airspeed ($13D)

D0[3] Baro correction hPa 100ms 319 FLOAT

($13F)

D0[4] Baro corrected altitude m 100ms 320 FLOAT

($140)

D0[5] Standard altitude m 100ms 322 FLOAT

($142)

D0[6] Lateral stick trim posi- % 100ms 402 FLOAT

tion command ($192)

D0[7] Longitudinal stick trim % 100ms 405 FLOAT

position command ($195)

D1[0] Engine RPM 1/min 100ms 500 FLOAT

($1F4)

D1[1] Propeller RPM 1/min 100ms 504 FLOAT

($1F8)

D1[2] Engine exhaust gas K 100ms 520 FLOAT

temperature (EGT) ($208)

D1[3] Engine fuel flow rate l/h 100ms 524 FLOAT

($20C)

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 Trans-
Tx Data
Parameter Name Unit mission CAN-ID
Slot Type
Interval

D1[4] Engine manifold hPa 100ms 528 FLOAT

pressure ($210)

D1[5] Engine oil hPa 100ms 532 FLOAT

pressure ($214)

D1[6] Engine oil K 100ms 536 FLOAT

temperature ($218)

D1[7] Engine cylinder head K 100ms 540 FLOAT

temperature (CHT) ($21C)

D2[0] Fuel tank #1 quantity kg 100ms 668 FLOAT

($29C)

D2[1] Fuel tank #2 quantity kg 100ms 669 FLOAT

($29D)

D2[2] Fuel system pressure hPa 100ms 684 FLOAT

($2AC)

D2[3] DC voltage V 100ms 920 FLOAT

($398)

D2[4] DC current A 100ms 930 FLOAT

($3A2)

D2[5] GPS height above m 100ms 1030 FLOAT

ellipsoid ($40E)

D2[6] GPS aircraft latitude deg 100ms 1036 FLOAT

($40c)

D2[7] GPS aircraft longitude deg 100ms 1037 FLOAT

($40D)

D3[0] GPS ground speed m/s 100ms 1039 FLOAT

($40F)

D3[1] GPS true track deg 100ms 1040 FLOAT

($410)

D3[2] DME distance m 100ms 1071 FLOAT

($42F)

D3[3] DME time-to-station min 100ms 1075 FLOAT

($433)

D3[4] DME ground speed m/s 100ms 1079 FLOAT

($437)

D3[5] ILS #1 localizer devia- deg 100ms 1087 FLOAT

tion ($43F)

D3[6] ILS #2 localizer devia- deg 100ms 1088 FLOAT

tion ($440)

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 Trans-
Tx Data
Parameter Name Unit mission CAN-ID
Slot Type
Interval

D3[7] ILS #1 glideslope deg 100ms 1091 FLOAT

deviation ($443)

D4[0] ILS #2 glideslope deg 100ms 1092 FLOAT

deviation ($444)

D4[1] VOR #1 radial deg 100ms 1126 FLOAT

($466)

D4[2] VOR #2 radial deg 100ms 1127 FLOAT

($467)

D4[3] ADF #1 relative bear- deg 100ms 1083 FLOAT

ing ($43B)

G0[0] Static air temperature K 1s 324 FLOAT

($144)

G0[1] Trim system switches 1s 439 BSHORT

event ($1B7)

G0[2] Trim system lights 1s 440 BSHORT

event ($1B8)

G0[3] Engine status 1s 556 BSHORT

event ($22C)

G0[4] VHF COM #1 fre- MHz 1s 1100 FLOAT

quency event ($44B)

G0[5] VHF COM #2 fre- MHz 1s 1101 FLOAT

quency event ($44C)

G0[6] Transponder #1 code BCD 1s 1116 FLOAT

event ($45C)

G0[7] ADF #1 frequency kHz 1s 1108 FLOAT

event ($454)

G0[8] VOR/ILS #1 frequency MHz 1s 1104 FLOAT

event ($450)

G0[9] VOR/ILS #2 frequency MHz 1s 1105 FLOAT

event ($451)

A transmission interval of 1s/event means that the respective para-

meter is transmitted once upon every state change and additionally
once a second if the state is unchanged.
Analyzing the Tx Slot fields, we find out that our baseline system re-
quires 9 parameters to be transmitted each 12.5ms, 32 parameters to
be transmitted each 100ms and 10 parameters to be transmitted once
a second. This results in the following transmission slot allocation:

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Revision 1.7, 12.1.2006

9 variables 8 parameters transmitted each 100ms

transmitted 8 parameters transmitted each 100ms
each 12.5ms 8 parameters transmitted each 100ms
8 parameters transmitted each 100ms
64 parameters transmitted each 1s

A0 A1 A2 A3 A4 A5 A6 A7 A8 D0 D1 D2 D3 G0
minor time frame 12.5ms

D0[0] D1[0] D2[0] D3[0] G0[0] minor time frame (n)

51/57

D0[1] D1[1] D2[1] D3[1] G0[1] minor time frame (n+1)

D0[2] D1[2] D2[2] D3[2] G0[2] minor time frame (n+2)

D0[3] D1[3] D2[3] D3[3] G0[3] minor time frame (n+3)

variables transmitted in D0[4] D1[4] D2[4] D3[4] G0[4]

(C) 1998-2006 Stock Flight Systems

subsequent minor timeframes minor time frame (n+4)

D0[5] D1[5] D2[5] D3[5] G0[5]
minor time frame (n+5)
D0[6] D1[6] D2[6] D3[6] G0[6]
minor time frame (n+6)
D0[7] D1[7] D2[7] D3[7] G0[7]
minor time frame (n+7)
D0[0] D1[0] D2[0] D3[0] G0[8] minor time frame (n+8)

..... .....
 The CAN bus data frame (11-bit identifier) has the following outline:
6.3 Bus load compu-
tation The CAN bus data frame (11-bit identifier) has the following outline:

data frame (44 + 0 ... 64 bit)

1 11 1 6 15 111 7

end of frame
ACK delimiter
ACK slot
CRC delimiter
CRC sequence field
data field (0 ... 8 data bytes)
control field (number of data bytes)
RTR (remote transmission request) bit
message identifier
start of frame
interframe space (>= 3 bits)

Most
Most CANaerospace
CANaerospace messages
messages use use all
all 8
8 bytes
bytes of
of the
the data
data field
field which
which
results
results in a message length of 44bits + 64bits = 108bits. To compute
in a message length of 44bits + 64bits = 108bits. To compute
the
the maximum
maximum bus bus capacity,
capacity, we
we have
have toto add
add the
the interframe
interframe space
space
(3bits)
(3bits) and a number of stuff bits (a maximum of 18 additional bits,
and a number of stuff bits (a maximum of 18 additional bits, we
we
assume
assume an average of 14) which gives a message length of 108bits +
an average of 14) which gives a message length of 108bits +
3bits
3bits +
+ 14bits
14bits == 125bits.
125bits. Assuming
Assuming the the maximum
maximum datadata transfer
transfer rate
rate of
of
1Mbit/s,
1Mbit/s, aa CANaerospace
CANaerospace message
message takes
takes 125s
125s toto transmit.
transmit. Hence,
Hence,
the CANaerospace bus capacity is 8.000 messages/second.
the CANaerospace bus capacity is 8.000 messages/second.
Defining
Defining a
a minor
minor time
time frame
frame of
of 12.5ms
12.5ms (80Hz)
(80Hz) results
results in
in 100
100 parame-
parame-
ters
ters which can be transmitted during this interval. This number can
which can be transmitted during this interval. This number can be
be
considered 100% bus load:
considered 100% bus load:
CANaerospace
CANaerospace message
message time:time: 125s
125s
Selected minor time frame:
Selected minor time frame: 12.5ms
12.5ms
100%
100% bus load: 12.5ms/125s = 100 messages
Byte bus load:1 Byte 2 Byte 3 Byte
0 Byte 12.5ms/125s
4 Byte 5 =Byte 100 6messages
Byte 7
For 29-bit identifier CAN messages (CAN 2.0B), the message time is
For 29-bit
145s, identifier
which resultsCAN messages
in 16% less bus(CAN 2.0B),
capacity thefor
than message time is
11-bit identifier
145s, Message
which results
CAN messages. Header
in 16%
If both 11-bitless
andbus capacity
29-bit than for
messages are11-bit
used identifier
at the
CAN messages. If both 11-bit and 29-bit messages
same time, the calculation should be done for each identifierare used type
at the
se-
same time, the calculation should be done for each identifier
perately and combined afterwards to assemble the resulting bus sche- type se-
perately and
dule data. combined afterwards to assemble the resulting bus sche-
dule data.
Our baseline system uses the following parameter/transmission inter-
Our baseline system uses the following parameter/transmission inter-
val matrix:
val matrix:

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 Required
Transmission Parameters/
Parameters Transmission
interval Transmission Slot
Slots

12.5ms 9 9 1
100ms 36 5 (4.5) 8 (0.1s/12.5*10-3s)
1s 10 1 (0.125) 80 (1s/12.5*10-3s)
total 55 15 (13.625)

As the baseline system uses 13.625 out of 100 available transmission

slots, the corresponding CANaerospace bus load is:

13.625%
Keeping in mind that asynchronous event data or node service data
might require additional bus capacity, we should leave some margin
for this (around 20%). Therefore, our system should not continously
exceed 80% bus load. Even though, this analysis shows that CANae-
rospace offers adequate growth capability for general aviation aircraft
avionics.

7 System redundancy support

The probability of an undetected data corruption in a CAN network is

around 1 * 10-13 per message transmission. Assuming 100% bus load
(around 8.000 messages per second), this will result in a probability of
2.9 * 10-6 undetected failures per flight hour, making CANaerospace a
candidate for mission and flight critical systems.
While this figure is better than for any other bus system available to-
day, it shows that a single CANaerospace bus (like all other buses) will
most likely not be adequate for flight critical systems, especially for
those requiring fail-operational behaviour. For those applications, sy-
stem redundancy is inevitable to demonstrate a required level of
functional safety.
7.1 Redundant mes- A system architecture as used by many modern integrated avionics
sage identifier and electronic flight control systems is shown below. In this architecu-
assignment re, two redundant units of the same type communicate via an equal
number of communication channels. Proper design provided, this sy-
stem will prevent a single failure to cause a complete loss of function:

AHRS 1 AHRS 2 ADC 1 ADC 2 FCC 1 FCC 2

Bus 1
Bus 2

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 Using the standard identifier distribution, each CANaerospace data
bus parameter has assigned a single, unique identifier (i.e. 304 for
body roll rate). This means that only one unit would be allowed to
transmit a particular parameter on the bus. A redundant system archi-
tecture as described is supported by CANaerospace, however, if the
29-bit identifiers are used. In this case, a redundancy level offset in
multiples of 65536 ($10000) is added to each identifier so that the
same parameter can be transmitted by several units using multiple
unique identifiers:

Example: Body Example: Body

Redundancy Redundancy
Roll Rate ID Roll Rate ID
Channel # Level Offset
(decimal) (hexadecimal)

0 0 304 $130
1 65536 65840 $10130
2 131072 131376 $20130
3 196608 196912 $30130
n 65536 * n 65536 * n + 304 $[10*n]130

7.2 System redun- Unlike other buses like ARINC429, ARINC629 or MIL-STD-1553B,
dancy and the CANaerospace is a dynamic network with a bus schedule that varies
CANaerospace within certain limits. Certification in flight safety critical applications,
header however, requires to demonstrate the proper function of the data trans-
mission under all conditions. Monitoring CANaerospace messages
during normal operation and processing the header information deli-
vers the required information for certification. Additionally, the header
information improves flexibility and supports dynamic network reconfi-
guration. Power down/up situations are handled gracefully, units may
be added to the network without software changes. Taking advantage
of the header information, CANaerospace bus analyzers and simula-
tors can be inserted even into a running network and will immediately
have all information about network structure, units and data. This en-
sures fast and cost-effective maintenance:

Byte 0 Byte 1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6 Byte 7

Message Header

Node-ID (Byte 0): Some system architectures employ backup

units which become active if the main unit fails. The Node-ID
allows to immediately identify this situation and react accor-
dingly (i.e. mode change within redundancy management).
Data Type (Byte 1): CANaerospace supports multiple data ty-

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 pes for every message. Backup units (or units from different
vendors) may use different data types while performing identi-
cal functions. Specifying the data type with each message al-
lows automatic system configuration, even during runtime.
Service Code (Byte 2): For Normal Operation Data, this byte
should continously reflect the status of the data (or the trans-
mitting unit) to support data integrity monitoring within recei-
ving units. With this information, the validity of data is known
at any given time.
Message Code (Byte 3): Message numbering allows to detect
if messages are missing and if the transmitting unit is opera-
ting properly. Also, it can be used to compare the "age" of
messages from redundant sources.

8 Physical connector definition

For CANaerospace, a physical connection suitable for airborne con-

nector types has been defined (connectors according to CiA DS102
are also supported). Note that unlike most other definitions for CAN
connections, CANaerospace connectors allows to supply +12-36VDC
power to the units via the CAN connector (+12-36VDC, Power
Ground). The RS-232 connection present on some of the connector
types is optional and may be used for maintenance or debug inter-
faces. Note also that the use of CAN Ground is supported by the con-
nector pinout but strongly discouraged due to potential EMC problems
in airborne applications as shown below:

CAN

DC DC
DC DC
improper CAN shielding
using CAN ground shield

CAN

DC DC
DC DC
proper CAN shielding
without CAN ground

Strongly encouraged is the use of optically isolated CAN interfaces for

all units in the network. For the wiring, AWG 22 aerospace standard
shielded twisted pair (STP) or shielded twisted quadruple (STQ)
should be used.
The pinout of the CANaerospace connectors is as follows:

Revision 1.7, 12.1.2006 55/57 (C) 1998-2006 Stock Flight Systems

 MIL-24308/8 connector (similar to CiA DS102)

Power +12-36VDC 1
CAN Low 2 6 RS-232 RxD
CAN Ground 3 7 CAN High
RS-232 TxD 4 8 Shield
Power Gnd 5 9 RS-232 Gnd

MIL-C-26482 connectors MS3470L1006PN (wall mount recepta-

cle) and MS3476L1006SN (mating straight plug)

A
F B

C
E
D

Pin A Power Gnd

Pin B +12-36VDC
Pin C Shield
Pin D CAN High
Pin E CAN Low
Pin F CAN Gnd

MIL-C-38999 connectors D38999/20FB35PN (wall mount recepta-

cle) and D38999/26FB35SN (mating straight plug)

1
2 11 10

3 9
12 13
4
8
5

6 7

Pin 1 +12-36VDC Pin 6 RS-232 RxD

Pin 2 CAN Low Pin 7 CAN High
Pin 3 CAN Gnd Pin 8 Shield
Pin 4 RS-232 TxD Pin 9 RS-232 Gnd
Pin 5 DC Gnd Pin 10-13 unused

Revision 1.7, 12.1.2006 56/57 (C) 1998-2006 Stock Flight Systems

 MIL-C-38999 connector D38999/20FA35PN (wall mount recepta-
cle) and D38999/26FA35SN (mating straight plug)

1
5
6
2 4

Pin 1 +12-36VDC Pin 4 CAN High

Pin 2 CAN Low Pin 5 DC Gnd
Pin 3 CAN Gnd Pin 6 Shield

A sample interconnection of multiple CANaerospace systems using

D38999/20FB35PN wall mount receptacles and D38999/26FB35SN
straight plugs is shown here:
Pinout Signal

Pin 1/B +12-36VDC

Pin 2/E CAN Low
Pin 3/F CAN Gnd
Pin 4 RS-232 TxD shielded twisted
pair or quadruple
Pin 5/A DC Gnd (CAN or CAN/power)
Pin 6 RS-232 RxD
Pin 7/D CAN High
Pin 8/C Shield
Pin 9 RS-232 Gnd
Pin 10 +12-36VDC
Pin 11 DC Gnd shielded twisted
Pin 12 CAN Low pair or quadruple
Pin 13 CAN High (CAN or CAN/power)

Note: The RS-232 lines defined for this connector type are optional
and may be used for device programming, configuration, etc. They
have no relationship to CAN or CANaerospace.

CANaerospace systems requiring high reliability or life-insertion capa-

bilities should be connected as shown below. The preferred CAN bus
topology is a shielded, twisted pair single line, terminated at both
ends. Units are connected via simple stubs within the connector.
Using this method, removing a unit from the bus (or reattaching it) will
not adversely affect the others: The bus is not opened by unplugging
the connectors:

Unit 1 Unit 2 Unit 3 Unit 4 Unit n-1 Unit n

CAN High
CAN Low

120 termination stub within 120 termination

connector

Revision 1.7, 12.1.2006 57/57 (C) 1998-2006 Stock Flight Systems