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Thread: Trane Comm 4

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  1. #1
    Join Date
    Dec 2007
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    Trane Comm 4

    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.

  2. #2
    Join Date
    Dec 2008
    Sydney, Australia
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    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.

  3. #3
    Join Date
    Mar 2011
    Long Beach, CA
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    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:

    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.

  4. #4
    Join Date
    Jun 2004
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    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.

  5. #5
    Join Date
    Mar 2011
    Long Beach, CA
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    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.

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