BACnet vs.
Lonworks Specifications (Network Guide)
SPECIFICATION BACNET (CH 2) LONWORKS (CH 3)
Connections IP, MS/TP, Ethernet TCP/IP with Fox connections
Topology Daisy chain (Bus) TP/FT10 (recommended)
BACnet – p. 17-19 Spur/ring/backbone and star topologies are (TP = twisted pair, FT = free topology)
Lon – pp. 39-40 UNSUPPORTED. Free (Ring, Star, Loop, Combo)
Termination Bus topology: Free Topology:
Requirements First and last device on the bus must have EOL One EOL anywhere on the segment
termination resistors (120 ohms) connected across the
BACnet – pp. 17-19
Lon – pp. 39-40
2 data lines/wires of the twisted pair. (See Network
Guide, CH 2, p. 17)
Cable Shielded twisted pair Unshielded twisted pair*
Requirements 24 AWG gauge Type 1 Cable: 22 AWG gauge
BACnet – p. 16 Type 2 Cable: 16 AWG gauge
Lon – p. 41 * Use shielded twisted pair for networks or portions of
networks that are run OUTSIDE buildings.
Wiring Length 1,220 meters (4,000 ft) TYPE 1 CABLE TYPE 2 CABLE
BACnet – p. 16 Bus topology: Bus topology:
Lon – p. 42 1,400 meters 2,700 meters (8,858 ft)
(4,593 ft) Free Topology:
Free Topology: 500 meters (1,640 ft)
500 meters
(1,640 ft)
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BACnet vs. Lonworks Specifications (Network Guide)
SPECIFICATION BACNET (CH 2) LONWORKS (CH 3)
Extending the Using a Repeater: A single repeater may be used to extend the
Data Bus No more than 2 repeaters > up to 3,660 m (12,000 ft) network, effectively doubling the max number
for the entire network – 3 segments of 4,000 ft each of devices from 64 to 128 (repeater counts as 1
BACnet – pp. 21-23
Lon – p. 43 Using an EC-BOS: device).
Up to 5 MS/TP networks when equipped with 2 Type 1 Cable: Extendible up to 2,800 meters (9,186 ft)
– Bus or 1,000 meters (3,280 ft) – Free
optional MS/TP network cards + installed RS-485 port
Type 2 Cable: Extendible up to 5,400 meters (17,716 ft)
(This depends on the MS/TP Feature limitation in the
– Bus or 1,000 meters (3,280 ft) – Free
license.)
Router recommended for best performance.
Could have up to 50 x 5 cards = 250 devices/BOS
Using an EC-BOS:
Up to 2 Lon option cards
Could have up to 256 devices/BOS (128 x 2
option cards) on a fully extended network.
Device Limits Up to 255 max 64 nodes (including Lon card)
(Per Segment) up to 128 (0 to 127) are Masters (128 when router or repeater is used)
(Per Network) up to 128 (128 to 255) are Slaves
32,385 (255 segments)
BACnet – p. 14
50 max (recommended) if all Distech controllers
Lon – p. 41
Max Nodes 32 50 – when using DC devices exclusively 64 (128)
250 – when equipped with 2 optional MS/TP
BACnet – p. 14
network cards + RS485 conn on the EC-BOS
Lon – p. 41
side (assuming you are licensed for them)
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BACnet vs. Lonworks Specifications (Network Guide)
SPECIFICATION BACNET (CH 2) LONWORKS (CH 3)
Polarity Sensitive YES NO
BACnet – pp. 12, 35 Maintain consistent polarity when connecting controllers/devices to the power transformer.
Lon – p. 46
Addressing MAC Address 0 – 255 Subnet/Node (no conflicts allowed)
(avoid gaps in 0 – bus master (EC-BOS) Program ID: Each device type is assigned a
BACnet – pp. 24-30
Lon – N/A addressing) 1, 2 – temp commissioning, reserved Program ID that identifies the vendor, usage,
format and controller model type
3 – 127 – Master range
Neuron ID: Each individual controller is
128 to 254 – Slave range
assigned a unique identifier
255 - broadcast
For certain ECB controllers (e.g., ECB-203), MAC address must
be set using an EC Smart Vue. Dip switches take precedence
over Smart Vue settings. When using the EC-Smart-Vue, the dip
switches must be set to default positions (see p. 29).
Device Instance Number: 0 to 4,194,303*
Vendor # + Network # + MAC Address
1 + 100 + 003
Example Device IDs = 1100003, 2200035, etc.
* Based on all 22 bits of the object ID set to 1.
Network 1 to 65,534
Number
Max Master Initially – 127
(EC-BOS) After device discovery – eliminate gaps in the
address range, reserving 3 to 5 more for spares.
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BACnet vs. Lonworks Specifications (Network Guide)
SPECIFICATION BACNET (CH 2) LONWORKS (CH 3)
Max Info Frames: EC-BOS 20
Max Info Frames: VAV/ECB-203 + 1
Max Info Frames: Stat 5
Power 24V COM terminal used as the required signal reference point See below.
for the data bus. The 24V COM/C terminals of all devices must
Requirements
be connected to the power supply bus that is grounded.
BACnet – pp. 32-36 DO NOT use a mechanical ground.
Lon – pp. 45-47 DO NOT use MSTP to connect BETWEEN buildings.
Avoid ground lift: excess voltage that develops over a long run
of cable connecting too many devices. If the ground lift is > 7
volts peak, there is risk of data corruption and offline events
due to the device being incapable of correctly reading data
signals from the data bus.
Transformer Selection: Use transformers of 100VA or less to power devices.
Calculate power requirements of all devices + external loads: multiply total power by 1.3 – choose a power
transformer just over this amount. Always use a SEPARATE transformer for EACH ECB-/ECL-series controller and
for EACH I//O extension.
External Loads: When calculating a controller’s power consumption, you must also add the external loads the
controller will drive, including any connected subnet modules such as EC-Smart-Vues. (See p. 50 for the total
number of EC-Smart-Vue controllers are supported by a given controller model.
VAV Device – Max Number: Depends on wire gauge and power run total cable length
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BACnet vs. Lonworks Specifications (Network Guide)
SPECIFICATION BACNET (CH 2) LONWORKS (CH 3)
Grounding Cable shield must be twisted together and isolated with Use shielded twisted pair for networks or portions of
electrical tape at each device. Shield on each network segment networks that are run OUTSIDE buildings, since it will
Practices
must be connected to electrical system ground at one only > at be subjected to EMI.
BACnet – p. 20 the Bus Master (EC-BOS). Grounding in more than one location The cable shield should be grounded using a capacitor
Lon – p. 44 could reduce shield effectiveness. to tie the shield to earth ground and large value resistor
should be used to bleed off any static charge on shield.
Data Rates 9600, 19200, 38400 (Distech recommends), 76800 baud 78 kbps (raw bit rate)
Master device sets the baud rate; all other devices set to 144/168 packets per second
BACnet – pp. 15-16
Lon – p. 41
AUTO. 180/210 packets per second MAX (peak traffic)
Distech recommends 38.4 baud for its controllers.
Troubleshooting SYMPTOM POSSIBLE CAUSE SYMPTOM POSSIBLE CAUSE
Issues Device doesn’t Power supply requirements Device doesn’t Power supply requirements
communicate Polarity reversed communicate Max # of devices on a network
BACnet – pp. 68-72
on the MSTP More than one device with same MAC on the Lon segment exceeded (64)
Lon – pp. 74-77
network address or Device ID network Absent or incorrect voltage
(For BACnet, see Baud rate is set to AUTO for ALL devices Overloaded power transformer
CH5 for solutions Device is set to MAC address outside of 3- Network not wired correctly
and a complete list 127 range Absent/incorrect network
of issues.) Max # of devices exceeded termination
Incorrect Max Master Supply voltage, overloaded
(For Lon, see CH6 for Gaps in the MAC addressing scheme transformer, or wiring issue
solutions and a EOL resistors missing Too many EC-Smart-Vue devices
complete list of Supply voltage, overloaded transformer, or providing network access
issues.) wiring issue (global/local values)
Inter-building comm attempted using
MSTP w/o first configuring BBMD Service
on each MSTP network – to allow
messages to be sent on IP via an IP router
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BACnet vs. Lonworks Specifications (Network Guide)
SPECIFICATION BACNET (CH 2) LONWORKS (CH 3)
Controller Wrong wire type Controller Network length exceeds specs
communicates Network wiring problem communicates Wrong wire type
well over short EOL resistors missing/incorrect well over short Network wiring problem
network, but Max # of devices exceeded network, but EOL resistors missing/incorrect
not over a large Incorrect Max Master not over a large Max # of devices on a network
network network segment exceeded (64)
Extra capacitance
Network traffic
HW input not Open/short circuit HW input not Open/short circuit
reading correct Configuration problem reading correct Configuration problem
value Over-voltage/current at an input value Over-voltage/current at an input
Blown fuse Input wiring problem
HW output not Output wiring problem HW output not Output wiring problem
operating Configuration problem operating Configuration problem
correctly Polarity of 24VAC power supply connected correctly Blown fuse
to actuator Polarity of 24VAC power supply
Device not associated to controller connected to actuator
Wireless Power discharge
devices not Device too far from receiver/Obstructions in line of signal
working Configuration problem
correctly
RX LED not Data not being received on bus
blinking
TX LED not Data not being sent on bus
blinking
STATUS LED See pp. 71-72 of Network Guide STATUS LED See pp. 76-77 of Network Guide
blinking blinking
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BACnet vs. Lonworks Specifications (Network Guide)
SPECIFICATION BACNET (CH 2) LONWORKS (CH 3)
BEFORE CALLING Before calling Technical Support, verify the following Before calling Technical Support, verify the
TECH SUPPORT recommendations have been carried out: following recommendations have been carried
Properly terminated MSTP data bus. out:
At least one device set to recommended baud rate with the Properly terminate the Lonworks data bus.
remainder set to AUTO. Connect no more than 5 devices to a power supply
Ensure that polarity of all data bus wiring is correct and transformer.
consistent.
Do not overload the data bus with COV reporting, since
these contribute to the most amount of network traffic.
Ensure there are no gaps in MAC addresses, and that the
Max Master is set to the last MAC address # on the network,
perhaps allowing several spaces for expansion.
ONLY daisy-chained devices – DO NOT use T-taps or star
configurations.
Connect no more than 5 devices to a power supply
transformer.
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BACnet vs. Lonworks Specifications (Network Guide)
SPECIFICATION BACNET (CH 2) LONWORKS (CH 3)
Pros/Cons Pros: Pros:
Usually cheaper and easier to install (MSTP) Generally more stable and forgiving
Less complex protocol In a bus topology, greater allowed cable
More aggressively marketed and supported length (8,858 ft vs. 4,000 ft)
Niagara (AX) objects are modeled after Bacnet Minimal initial setup
objects Cons:
Cons: Steeper learning curve
Polarity sensitive More complex protocol/rules
More extensive initial setup (e.g., network #, Usually greater initial cost (installation)
MAC address, device ID, baud rate) LOTS of vendor-/model-specific modules
Must be “tweaked” to achieve optimal
performance
More aggressively marketed
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