User manual

Troubleshooting
Remote I/O 5-19
Classic PLC-5
processors only
troubleshooting – remote I/O system, 1771-ASB series C and series D continued...
See page 5-20 for footnotes
☞
Indicators
Active Adapter
Fault
I/O
Rack
Description Probable Cause Recommended Action
Off Off On I/O chassis fault.
2
No
communication on
link.
Problem exists between:
• adapter and module in chassis; the
module will stay in fault mode until
fault is corrected
• shorted printed circuit board runs on
backplane or I/O module
Cycle power to the chassis to clear a problem
resulting from high noise
3
• Remove and replace all I/O modules one
at a time
• If the problem does not clear, something
is wrong in chassis or I/O module
Blink Off On Communication on
link. Possible shorted
backplane
• noise on backplane
• shorted circuit board runs
• faulty card in chassis
• Eliminate noise
• Isolate noise
• Add surge suppression
• Replace chassis
• Replace defective card in chassis
Blink On Off module identification
line fault
excessive noise on backplane Verify power supply and chassis grounding
ACTIVE
ADAPTER
FAULT
I/O RACK
FAULT