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Troubleshooting
Remote I/O
5-18
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
Blink
Off
Off
remote adapter not actively
controlling I/O (scanner to
adapter communication link is
normal)
4
processor is in program or test
mode
scanner is holding adapter
module in fault mode
Fault should be cleared by I/O scanner
LEDs sequence on/off from top
to bottom
module not communicating
another remote I/O adapter
with the same address is on the
link
Correct the address
Blink alternately
Off
adapter module not actively
controlling I/O
2
adapter module in processor
restart lockout mode (adapter
to scanner link is normal)
processor restart lockout
switch on chassis backplane
switch assembly on
1
Depress reset button to clear lockout feature or
cycle power; if after repeated attempts indicators
are still blinking, check:
• push-button not wired properly to field
wiring arm
• wiring arm not connected to
adapter module
• adapter module was reset by
processor/scanner, then immediately faulted
ACTIVE
ADAPTER
FAULT
I/O RACK
FAULT