Trane Comm 4

[zigmund]

What exactly is the Trane comm 4 protocol...RS-485? Is there an extender or repeater for this comm link that anyone's used successfully. I see various RS-485 repeaters by different vendors. I don't necessarily need more distance but I'm wondering if I could use it to boost signal on existing comm 4 links with higher capacitance cable that was put in years ago.

[iControl HVAC]

My understanding is that Comm4 is basically Modbus RTU with a different format of checksum. Based on that - any 485 repeater should work just fine, I suppose the main thing to look for is whichever one you can find with the lowest propogation delay so you don't get any 'time-out' problems.

[alcomech]

Comm cards are used for different types of equipment such a VAV's and there various types, Voyager, Intellipaks, self contained equipemnt, chillers, etc etc.

The following is a short list which I use to identify Comm or configuration.

BCU Comm Cards:
Comm2 Red:
UCP1

Non Isol.Comm3 Link (Up to 2) (RTA, SWUD,) Green: VAV I, TRS

Isolated Comm 3 Link (up to 4)
LCP Supervisor, TCM, PCM, RTA/RTW, Varitrac II CCP, Scroll Chiller, Com Self Contained.

Comm4 Green (VAV II/III/IV, Intellipak, UCP2, TUC, Voyager Horizon, UPCM, Absorption Chiller)
Tracer Version 12 has a maximum of 64 Tracer addresses out of an available range 1 through 81
Tracer Version 13 has a maximum of 32 Voyager Micro Rooftop TCI-3s for Tracer 100. A maximum of 20 Voyager for Tracer L and Monitor.
The range of Tracer address numbers that may be defined for Voyager Micro Rooftop TCI-3s is 50 through 81
(NOTE: when communicating with a UCM Via Trane Everyware Software, You must add 64 base to the unit address).

Ref to TCI-3 For info Lit: EMTX-IN-16

Comm5 Link (1) Green (Tracer Controllers, Lontalk, AH540, AH541, MP501, MP580/ MP581, Generic LonTalk Devices)
Communication is 78,000 bps
Open protocol support
Neuron ID numbers
Daisy chain requires a 100 ohm Resistor @ Each end of link.
Branch require a 50 ohm resistor at the BCU or the repeater
Use only one type of wire for comm 5
Comm5 UCM (unit control modules) are unique because they do not have a field-configurable DIP switch address. They have a Neuron ID.
Refer to Page 151 Hardware and soft

Up to 4 Links on the BCU
Maximum VAV Devices Per Link 63
Maximum VAV per BCU 126 Stand Ca.
192 Max with High Capacity

VAV I & IA: Address 1 to 63
VAV II, II, IV: address 65 to 127

Tracer MP580/581 LonMark requires Customized Programming and configurations using Rover service tool software version 3.0 or higher.
Lon Talk Devices Lit: BAS-PRB003-EN
Use Neuron ID printed on logic bord @ UCM.

____________________________
Trouble shooting is not part of the repair..........understand the symptoms and you will find a solution.

[shovelhead]

zigmund, I worked for Trane for 16 years and don't recall ever seeing a comm4 like repeated. These links typically had in the 30's number of devices and up to around 400 feet of wire. It is polarity sensative and a BMTW BCU can have up to 4 cards as pointed out above, the BMTX doesn't have daugther boards.

[alcomech]

A fiber-optic Comm3 or Comm4 communication link uses EIA-485 data transceivers (IFS D1300) and EIA-485 data repeaters (IFS D2300), which are referred to as fiber-optic modems.

Comm 5 should use a repeater when the comm line is over 4500 ft.