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Excessive Loss of Communication

Updated

Issue:

Communication diagnostics, with the exception of “Excessive Loss of Comm”,  are named by the Functional Name of the input or output that is no longer being heard from by the Main Processor. Many LLIDs, such as the Quad Relay LLID, have more than one functional output associated with it.  A comm loss with such a multiple function board, will generate multiple diagnostics.  Refer to the Chiller’s wiring diagrams to relate the occurrence of multiple communication diagnostics back to the physical LLID boards that they have been assigned to (bound).

 

Communication loss diagnostics will not occur unless that input or output is required to be present by the particular configuration and installed options for the chiller.  

 

Resolution:

Refer to troubleshooting manuals RTAC-SVD01A-EN and RLC-SVD05A-EN under sections IPC Overview and Troubleshooting.  Follow the flow chart in this section and check power supply voltages under the power supply checkout in this manual.

 

Use following steps to guide you with the troubleshooting process.

 

  • Validate MP software on controller is up to date
  • When connecting to chiller, make sure using Rover adapter with dip switches set correctly or USB to serial cable. For Comm Port or Rover Tool settings information refer to Hub Solution Unrecognized Product Information - Techview  
  • Inspect cabling, frame LLIDs, and panel LLIDs for loose connections, damaged cables, evidence of moisture ingress
  • Check Binding View for devices not verified
    • All LEDs On is a good test. It tells you that the 24 VDC is present to the LLID and the two communications wires are connected
    • If LED does not go on but goes on with a south pole magnet, then the 24 VDC is present but the comm link is open.
    • If the LED doesn’t go on with the magnet, check for 24 VDC at the global connector or at the IPC buss if there are multiple devices.
  • Check power supply for voltage
    • 27 VAC in at J2
    • 24 VDC at J1, J11, J3, J4, J5
    • Verify control voltage (blue/gray or green/white) is 3-5 VDC
  • Multiple LLID’s Not Communicating
    • Turn off power to machine
    • Disconnect Frame LLID’s from buss
      • CGAM from the 1A17 (J1/J11)
      • RTAC from power supply
    • Turn on power to machine
    • Connect to chiller and go to binding view
      • All frame LLID’s should be RED, if Panel LLID’s are red, disconnect BACnet from buss if it is present, then rebuild view
      • If any panel LLID’s are RED, bind them.  If unable to bind, likely a bad LLID
      • Connect the Frame LLID’s, if a short is present, Divide and Conquer Method should be used
      • Disconnect a branch of the buss at time to narrow the portion of the buss or LLID’s that is bringing down the buss and select Rebuild view (refer to the correct frame LLID layout)
      • Determine which LLID’s should be RED and which ones should be GREEN to determine the next branch of cables to work on
      • If needed, you can take the ohm reading of global connector that is removed to ensure there is power, reference Global CH530 connector female pin signals for Global connector plug wire identification.
      • It may be necessary to unplug all panel LLID’s or all Frame LLID’s and plug in one at a time, selecting rebuild view until the LLID that is bringing down the bus is identified
  • Refer to appropriate attachments below for detailed layouts of the global wiring harness.  The wiring schematic should also be referenced for troubleshooting loss of communication diagnostics.

 

Notes:

It may be possible to get this same diagnostic if the wiring to the Dynaview is loose. Check the connector going into the Dynaview for any loose or frayed wires.

It may be possible to get same diagnostics if BACnet is bad or UC400/BCI-R/BCI2-C has been not programmed as BCI-C.

 

Resources Available:

  • Tech TV Video(s):
    • N/A
  • Reference Literature:
    (Electronic copies can be pulled from e-library at https://elibrary.tranetechnologies.com/residential/)
    • RTAC-SVD01A-EN - Diagnostic Troubleshooting Repair RTAC
    • RLC-SVD05A-EN - CH530 Troubleshooting Diagnostic Troubleshooting Repair
    • BAS-SVN045J-EN - Rover Tool Installation Guide
  • Other:
    • Very useful information can be found in KestrelView under "Service Documents"

Changes:

 

Other Question/Problem/Cause Statements:

  • Excessive communication loss CH530
  • Excessive comm loss.
  • All communications have been lost and cannot bind anything.

Facts:

  • Air-Cooled Chiller (Pueblo) (RTAC)
  • Water-Cooled Chiller (Pueblo) (RTHD)
  • RTAC
  • Found cut on 24 volt section of bus. Repaired and no change.
  • Found several loose butterfly connectors. Recrimped and no change.
  • Intermittent problem at first, now has evolved into a constant problem.
  • Incoming 24 Vac power is good and fuse is good on the 1U2 power supply module.
  • There is no 24 Vdc power indicated coming out of the 1U2 power supply module on any of the J4-1, J3-1, and J1-1 terminals.

Document Identifier: DOC-81331

Document Identifier: 81331

 

WARNING:

Information in this article is intended for use by individuals possessing adequate backgrounds of electrical and mechanical experience and who comply with all federal, state, and local laws, rules, orders, or regulations related to the installation, service, or repair of a heating or central air conditioning product. Any attempt to install, service, or repair a heating or central air conditioning product may result in personal injury and/or property damage. The manufacturer or seller cannot be responsible for the interpretation of the information contained herein, nor can it assume any liability in connection with its use.

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