Procedure #9 - Rs-485; Table 7-13 Troubleshooting A Rs-485 Communications Failure - Honeywell UDC3500 Product Manual

Troubleshooting/Service
7.7.9 Procedure #9 – RS-485
Table 7-13 explains how to troubleshoot a RS 485 Communications failure.

Table 7-13 Troubleshooting a RS-485 Communications Failure

Step
1 Check the Address Number,
ComState and Baud Rate
settings.
2 Check if the controller is wired
correctly to the Network.
3 Determine if the
Communications board is faulty
by running a LOCAL
LOOPBACK TEST.
If the test fails, replace the
board. If the test passes, the
problem is most likely
elsewhere in the
communications network.
328
What to do
UDC3500 Universal Digital Controller Product Manual
How to do it
See Section 3.23.
See Section 2.7 for wiring diagrams.
Disconnect the communications cable from the
rear terminals. Run the Local Loopback Test.
Press key until you see:
Setup
Upper Display
SET UP
Lower Display
COM
Press key until you see:
Func-Loop 1/2
Upper Display
DISABLE
Lower Display
LOOPBACK
Press or and you will see:
Upper Display
ENABLE
Lower Display
LOOPBACK
key and you will see:
Press
Lower Display
Upper Display
START
Lower Display
LOOPBACK
Then you will see either PASS or FAIL in the
Upper Display. The test will run until the
operator disables it or until the unit is power-
cycled.
If you see FAIL, go to Step 4. If you see PASS,
then the problem is most likely not in the
instrument, but somewhere else in the
network. Reconnect the communications cable
and then go to Step 7.
3/07