MICROMASTER (MM4): What are the possible causes of

F0070 on MICROMASTER 4, and how do I avoid them?

FAQ Ÿ November 2013

Siemens Industry Online Support

Answers for industry.
 Table of contents

Causes and avoidence of F0070 / 223

Table of contents
1 Conditions of LED .......................................................................................... 3
1.1 Problems that could cause the LED to go orange ............................... 3
1.1.1 Poor PROFIBUS signal...................................................................... 3
1.1.2 Poor PROFIBUS connection .............................................................. 4
1.1.3 External problems.............................................................................. 4
1.2 Problems that can cause the LED to go read are ............................... 4
1.2.1 EMC problems................................................................................... 4
1.2.2 Incorrect fitting of the PROFIBUS module .......................................... 5
2 Measures to avoid problems.......................................................................... 6
2.1 EMC correct installation ..................................................................... 6
2.2 Correct lay of PROFIBUS cable ......................................................... 9
2.3 Telegram off time............................................................................... 9
3 Fault F0070 in conjunction with control panel ............................................ 11
4 When fieldbus communication fails, how can fault F0070 be
detected by the drive inverter and further processed? .............................. 12
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5 History .......................................................................................................... 14
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 Conditions of LED

Causes and avoidence of F0070 / 223

1 Conditions of LED
On MICROMASTER 4 there is only one fault code, F0070, for PROFIBUS
communications failure. If the fault is due to failure of communication with the
PROFIBUS Master, the LED on the PROFIBUS module goes orange, if it is due to
MM to PROFIBUS module comes failure, it goes red.

1.1 Problems that could cause the LED to go orange

1.1.1 Poor PROFIBUS signal

Possible causes are electrical interference (EMC), signal attenuation due to

excessive cable lengths, reflections due to cable joints or incorrectly installed
connectors, incorrect bus termination, or inadmissible spurs on the bus (T-offs).
Check the PROFIBUS with an oscilloscope, an example of a good waveform is
shown below (1.5 Mbaud). The BT200 PROFIBUS Tester (6ES7181-0AA01-0AA0)
is also useful for checking PROFIBUS hardware.
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Figure 1-1
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 Conditions of LED

Causes and avoidence of F0070 / 223

Figure 1-2
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FAQ_en__for_MM.docx

1.1.2 Poor PROFIBUS connection

This may be due to the PROFIBUS connector not being correctly inserted, or the
contacts on quick connect connectors (e.g. 6GK1 500-0FC00) not being pushed
fully onto the cable. Ensure the connection knives are pushed firmly home.
Checking with a standard multimeter may identify such problems.

1.1.3 External problems

Also consider external problems, such as disturbances caused by other nodes on

the PROFIBUS, and PLC programming errors.

If you look at the PROFIBUS traffic (with a data analysis tool such as Amprolyzer)
when there is an EMC or PROFIBUS signal quality problem causing the LED to go
orange, you’re likely to see occasional error frames and the PLC sending repeat
messages (retries).

1.2 Problems that can cause the LED to go read are

1.2.1 EMC problems

On MM420/430/440, the most likely sources are voltage spikes coming in on the
analogue I/O, and for MM430/440 on the motor PTC/KTY input, which are not
isolated. As motor PTC/KTY cables are often installed close to motor cables

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 Conditions of LED

Causes and avoidence of F0070 / 223

without proper screening or segregation, excessive noise coming in on the

MM430/440 motor PTC/KTY input is a common cause of problems.

On MM411 the digital inputs are not fully isolated, and voltage spikes coming in via
these can have the same effect as the analogue I/O and motor PTC/KTY inputs on
MM420/430/440

1.2.2 Incorrect fitting of the PROFIBUS module

Check the PROFIBUS module is firmly engaged on the MICROMASTER, and that
the connectors on the rear of the module and the front of the MICROMASTER (or
encoder module) are not damaged.
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 Measures to avoid problems

Causes and avoidence of F0070 / 223

2 Measures to avoid problems

2.1 EMC correct installation
EMC correct installation is the key to reliable operation.

Ensure the bus cables are separated by at least 20cm from all cables, and power
cables in particular, and that they cross these cables at right angles.

Maintain equipotential bonding between different PROFIBUS stations by

connecting the stations' PE together using heavy copper conductors or wide flat
braid. If there is a poor earth, current will flow in the PROFIBUS cable screen,
which is likely to lead to data corruption. If the bonding is uncertain (e.g. if nodes
are different buildings) consider the use of optical links. To give a good EMC earth
to the PROFIBUS cable screen, it should be grounded use screen clamps making
360 degree contact. Brass or copper P clips are often a convenient way of doing
this.
Where there are short cables connecting within a group of MICROMASTERS (e.g.
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a row in a cubicle), one ground connection per 2 MICROMASTERS is usually

adequate. For cables of several metres or more there should be one ground
connection at each of the cable.
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Figure 2-1

Particular attention should be given to motor cables. These should be screened

with steel braid (type SY), or preferably copper braid (CY). If the equipment has to
meet Class A radiated emissions limits CY cable is normally required. If possible
run the cable without joints direct from the MICROMASTER to the motor. At the
motor use an EMC gland that makes 360 degree contact with the cable screen.
Examples of EMC glands are shown below. At the MICROMASTER a good EMC
ground connection is needed to the backplate on which the MICROMASTER is

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 Measures to avoid problems

Causes and avoidence of F0070 / 223

mounted. On smaller drives this can be done using a copper or brass P clip similar
to those used for the Profibus cable. On larger drives a cable clamping rail or
suitable EMC gland will probably be needed. If joints cannot be avoided, the EMC
integrity of the cable screen must be ensured. For example, if a local isolator is
mounted near the motor, it should be mounted in a metal box with EMC glands.

Figure 2-2
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 Measures to avoid problems

Causes and avoidence of F0070 / 223

Figure 2-3
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Particular care should be taken with the motor PTC/KTY input on MM430/440. The
FAQ_en__for_MM.docx

cable to this should be screened and effectively separated from the motor power
cable. You can do this either by running it separately from the power cable, or
ensuring the power cable is well screened. If a motor PTC is used, a better
immunity is obtained by connecting it to a digital input (which is fully isolated). The
parameter P70x for the input is set to 29, an external fault F0085 occurs when
motor overtemperature is detected. To get the better immunity, the analogue 0V
(terminal 2) must not be connected to the isolated 0V (terminal 28).

Figure 2-4

Further information on EMC correct installation can be found in the SD Engineering

info No. 6:
http://support.automation.siemens.com/WW/view/en/18162267

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 Measures to avoid problems

Causes and avoidence of F0070 / 223

2.2 Correct lay of PROFIBUS cable

Ensure the bus is correctly terminated at both ends. The nodes where the bus is
terminated must always have power available to provide the 5V supply for pull up/
down. For MM4 this can be achieved by connecting a permanent 24V supply to the
Profibus module. Observe the maximum and minimum cable lengths, and use the
recommended cable and connectors. Use repeaters when needed. For details see
the Simatic Net publication:

http://support.automation.siemens.com/WW/view/en/1971286

This is a summary of some of the important points from this document:

- Maximum total cable lengths for a Profibus segment are:

Up to 187.5 kbaud 1000m

Up to 500 kbaud 400m
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Up to 1.5 Mbaud 200m

Up to 12 Mbaud 100m
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- Minimum lengths for the cable between 2 nodes are specified in section 3.1.2 of
the Simatic Net publication. As long as the connectors recommended for MM4 are
used (6GK1500-0FC00 or 6GK1500-0EA02), then the minimum cable length
between 2 MICROMASTERS is 200mm for up to 1.5 Mbaud. For higher
transmission rates a minimum cable length between nodes of up to 600mm should
be considered. For other connector types or configurations refer to the Simatic Net
publication.

- a maximum of 32 nodes is permitted on a Profibus segment. If more nodes are to

be connected, repeaters have to be used. Note each side of a repeater counts as 1
node.

Limitation of use in safety critical applications

Do remember that MICROMASTER 4 is a single channel electronic control system,

and is not specified to meet the machine safety standards such as EN 954 and
IEC61508. External safety systems are required to comply with such standards.
Typically these take actions such as monitoring machine speed, isolating the AC
input power to the MICROMASTER, and applying mechanical brakes.

2.3 Telegram off time

In general, for problems that lead to short term MICROMASTER to Profibus
module comms failure, F0070 can be avoided if P2040 is set to c. 3000ms. The
MICROMASTER will continue running at the speed reference in the last received
telegram, so the reliability and safety of the machine or system must be

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 Measures to avoid problems

Causes and avoidence of F0070 / 223

considered. The setting P2040 = 3000ms is based on experience (temporary

communications breakdowns last 1 to 2 seconds). The LED can be seen changing
from green to red for 1 to 2 seconds. If you look at the Profibus traffic when this
happens (with a data analysis tool such as Amprolyzer), you’ll see the PLC
repeatedly sends diagnostic requests because the MICROMASTER is unable to
reply correctly.
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 Fault F0070 in conjunction with control panel

Causes and avoidence of F0070 / 223

3 Fault F0070 in conjunction with control

panel
This description is only valid for firmware <3.0!

When STARTER takes control, two windows will appear. The second window is
shown below. Please change the application monitoring time to a value greater
than 2 seconds (e.g. 5000ms). Then fault F0070 should not appear again.
This change should also improve the response time for STARTER to take control.

Figure 3-1
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 When fieldbus communication fails, how can fault F0070 be
detected by the drive inverter and further processed?

Causes and avoidence of F0070 / 223

4 When fieldbus communication fails, how

can fault F0070 be detected by the drive
inverter and further processed?
In many applications, when fieldbus (PROFIBUS, PROFINET) communication fails
with fault F0070, it is desired to have a bit that signals that fieldbus has failed, and
that can then also be freely interconnected. This means that the user can
specifically evaluate this fault and himself decide which response is to be made.
The bit can be generated using free blocks (FFB). This is the reason that the
recommended method can only be implemented at the MM430 / MM440 and G120
/ G120D with CU240S/D DP/DP-F / CU240S/D PN/PN-F.

Parameterization:
P2800 = 1 // Activate FFB
P2801.0 = 1 // Enable AND 1 (level 1)
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P2802.12 = 2 // Enable comparator 1 (level 2)

P2802.13 = 2 // Enable comparator 2 (level 2)
P2810.0 = r2886.0 // 1st input of AND 1 = output of comparator 1
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P2810.1 = r2888.0 // 2nd input of AND 1 = output of comparator 2

P2885.0 = r0947.0 // 1st input of comparator 1 = last fault code
P2885.1 = P2889 // 2nd input of comparator 1 = fixed setpoint 1
P2887.0 = P2889 // 1st input of comparator 2 = fixed setpoint 1
P2887.1 = r0947.0 // 2nd input of comparator 2 = last fault code
P2889 = 0.43 // Fixed setpoint 1 = 0.43% (the value is only valid for F0070)

r2811 = 1 for fault F0070

Bit r2811 can be used for further BiCo interconnections.

Note: The value 0.43% results from the formula:

This method can be used for all faults.

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 When fieldbus communication fails, how can fault F0070 be
detected by the drive inverter and further processed?

Causes and avoidence of F0070 / 223

Figure 4-1: Detecting fault F0070

Bit r2811 can be used, e.g. for "remote / local" changeover (P0810 / P0811). To do
this, in addition, a flip-flop and a logical OR are parameterized.
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Note: Fault F0070 must be acknowledged after changing over between the two
command data sets.
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Parameterization:
P0704.0 = 99 // Enable BiCo parameterization for digital input 3/4 (DI3/4)
P2801.3 = 1 // Enable OR1 (level 1)
P2801.14 = 1 // Enable RS-FF 1 (level 1)
P2816.0 = r0722.3 // 1st input of OR1 = DI3/4
P2816.1 = r2090.10 // 2nd input of OR1 = Bit r2090.10 (control from PLC)
P2840.0 = r2811.0 // Set input of RS-FF 1 = output of the AND 1 (Bit r2811)
P2840.1 = r2817.0 // Reset input of RS-FF 1 = output of the OR1
P0810 = r2841.0 // CDS Bit0 (remote / local) = output of the RS-FF 1

Figure 3-2: REMOTE / LOCAL changeover

Also read the application document on this subject

Entry-ID: 22533468 „Profibus monitoring and “LOCAL / REMOTE” changeover“

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 History

Causes and avoidence of F0070 / 223

5 History
Tabelle 5 History
Version Date Changes
V1.0 11/2013 First issue
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