Trane BACnet MS/TP - Troubleshooting Options

39 BAS-SVX51L-EN
Troubleshooting Options
Use Table 7, p. 39 to quickly identify the symptom and some possible causes, then refer to the best
practices section of this document for information on fixing the problem.
Table 7. Troubleshooting quick reference
Symptom Possible Causes
Intermittent communication or communication is down
• Using the wrong type of wire.
• Wire run is too long.
• Too many devices on the link.
• Wrong wire topology.
• Problem with Terminators (i.e., missing, too few, too many, not powered, etc.).
• Improper wire connections at the terminals on the device.
• Bad ground connection at the device.
• Both ends of the shield wire not grounded.
• Open connection of shield wire.
• Short in communication wire to ground.
• Short between communication wires.
• Baud rate mismatch.
• Duplicate rotary switch address.
• External electrical interference.
Device not found
• Non-conforming third-party device, or device is not using BACnet
®
protocol.
• Reverse ground at a device (swapped 24 Vac wire with ground wire with a common power transformer)
Transformer shared with device and other non-controller devices in an enclosure.
• Reverse ground at a device (swapped 24 Vac wire with ground wire with a common power transformer)
Multiple unit controllers sharing a transformer.
• Bad ground connection at the device.
• Loose terminals.
• Device not configured for BACnet
®
communications.
• Rotary dial error (address set to “0” with dials).
• Trane rotary dial value set to zero.
• Max Manager property set to low.
• Device powered down.
Tracer
®
SC+ cannot install devices above 60 devices
• Too many devices on the link.
All down-stream devices not found
• Break in wire (both wires).
• Break in wire (one wire).
• Loose terminals.
• Bad wire connection at the device.
• Reverse polarity of +/- communication wires.
• Incorrect connector placement
(a)
.
Two devices not communicating
• Duplicate rotary switch Address.
Communication time-outs, slow data response to query
• Link data traffic overload.
• TGP2 data requests are too frequent.
• Data log requests are too frequent.
• Too many data logs gathering information.
(a) In the UC400 and UC600 controller design, there is a female terminal connector that the MS/TP and IMC communication buss share. It is common to miss-align the MS/TP
connector and connect one line of the network to an IMC terminal.