Table 7-12 Troubleshooting A Rs-485 Communications Failure - Honeywell UDC3200 Product Manual

Procedure #8
Table 7-11 explains how to troubleshoot a RS 485 Communications failure.

Table 7-12 Troubleshooting a RS-485 Communications Failure

Step
Check the Address Number,
1
ComState and Baud Rate settings.
2 Check the field wiring and
termination resistor.
3 Make sure the Communications
Printed Wiring Board is installed
properly in the controller.
Determine if the Communications
4
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.
12/04
What to do
UDC3200 Universal Digital Controller Product Manual
How to do it
See Section 3.13.
Using an ohm meter, check the resistance across
the communications rear terminals. See Section
2.7 for wiring diagrams.
Withdraw the chassis from the case and inspect the
board. See the exploded view (F
location of the board. Return the chassis to the
case.
Disconnect the communications cable from the rear
terminals. Run the Local Loopback Test.
Press [SET UP] until you see:
Upper Display
SET UP
Lower Display
COM
Press [FUNCTION] until you see:
Upper Display
DISABLE
Lower Display
LOOPBACK
Press or you will see:
Upper Display
ENABLE
Lower Display
LOOPBACK
The test will run until the operator disables it here.
Troubleshooting/Service
igure 8-1 ) for
167