Allen-Bradley ControlLogix 1756-DH485, User Manual, Page: 100 / 110

Publication 1756-UM532A-EN-P - May 2006
B-4 Troubleshoot the 1756-DH485 Module
Interpret the OK
Status Indicator
The three LED status indicators on the module provide information about
your module and the status of each channel. The following tables outline the
indicator condition and the corresponding status, and explain what each
condition means.
Interpreting the OK Status Indicator
Routing Errors in DH-485
Messaging
This section describes routing errors in local and remote messaging.
Routing Errors in Local DH-485 Messaging
If the 1756-DH485 module has a problem with routing a DH-485 message, it
may return a response with an error status of D0 hex. A PLC-5 controller
displays this error as D000 hex when monitoring the message instruction. If
you receive this error message, take the following actions:
•
Check your message instruction to make sure a valid destination node
was entered.
•
Check your default slot configuration to make sure that it matches the
location of the ControlLogix controller in the chassis.
•
Make sure the 1756-DH485 module is turned on and verify chassis
power is recognized by the 1756-DH485 module.
If the Module OK
Indicator is Module Status Recommended Action
Off Not operating. Apply chassis power.
Verify module is completely inserted into
chassis and backplane.
Red, then Off Performing self-test. None, normal operation.
Green Operating and routing
messages. Verify module configuration.
Red In major fault Reboot module. If red reoccurs, then
replace module.