Rockwell Automation 1791-XXXX Discrete I/O AC and DC Block I/O Input and Output Modules - Manual (Page 72)

Troubleshooting
Chapter 5
5-2
Table 5.A
Troubleshooting Chart
Indication Probable Cause Corrective Action
Green COMM indicator on
Red STATUS indicator off
I/O status indicator on/off
Normal operation None required
Red STATUS indicator on Block failed selfĆtest, or a major fault is detected.
Cycle power to the block. If problem persists,
replace the block.
Red STATUS indicator flashing
Green COMM indicator off
Communication failure - RIO cable off, 100ms
between valid frames, 20ms idle time exceeded.
Improper processor or scanner switch settings.
Check remote I/O cable connections, verify
scanner or processor switch settings.
Green COMM indicator off No communication with processor, scanner etc.
Check that power is applied to block.
Make sure that proper number of blocks are
configured.
Check remote I/O link for duplicate address.
Green COMM indicator flashing
Reset command (or output disable bit for SLC) has
been issued by processor or scanner.
Check program. Correct as necessary.
Check terminator, resistors and cable wiring.
Green COMM indicator flashing
SLC or programmable controller in program mode. Place in run mode.
COMM and STATUS indicators
alternately flashing
Processor restart lockout is selected and a fault
has occurred. (Communication to block is
established.)
Cycle power to block.