Rockwell Automation 1771-KA2 Communication Adapter Module - Manual (Page 122)

Start–up and Troubleshooting
Chapter 9
9-20
on the program panel or industrial terminal, observe the status indicators
of the terminal carefully. Due to CRT delay time, the intensity of an
EXAMINE OFF instruction, which shows its status, may not change as
rapidly as does the actual ON/OFF status of the FAULT bit. (Recall that
programming re-tries caused the FAULT bit to be continuously turned ON
and OFF.) Thus, it may take a few seconds for the programming terminal
to show a change in FAULT bit status.
Should it be difficult to detect the changing ON/OFF bit status for an
individual FAULT bit, the contact histogram feature can be used to
display changes in status.
4. From the results of step 3, determine the START bit address for the
corresponding command.
The START bit has a strictly defined correspondence to a REMOTE or
LOCAL FAULT bit. Figure 6.2 shows this relationship.
5. Use the SEARCH functions to locate the command rung that begins
with the START bit, as determined in the previous step.
6. Examine the command code of this rung to determine the remote
station number to which the command was sent.
7. Determine the nature of the faulted condition and correct this
condition.
Use Figure 9.3 as a guide to tracing possible sources of a faulted
condition.
8. Verify that the FAULT condition was corrected. Observe the fault
indicator at the sending station.
Module Replacement
After other troubleshooting checks have been made, it may be necessary
to replace the communication adapter module.
Removing the Module
1. Turn off power to the module.
This power is provided by the power supply that connects to the
backplane of the Bulletin 1771 I/O chassis.
2. Disconnect all cables connected to module sockets.
3. A plastic latch on the top of the chassis holds the module in place.
Pivot this latch upward, out of the way of the module.