Rockwell Automation Publication 1794-UM061B-EN-P - March 2020 109
Interpret the Indicators Appendix A
1794-OB16D Diagnostic
Functional Details
Two module indicators and four diagnostic bits report fault conditions:
• the module fault indicator illuminates red and the individual faulted
channel indicator also illuminates red under output ON state open and
output OFF state short conditions.
• the module fault indicator illuminates red for reverse user power
conditions.
• the open bit is set for open load and wiring conditions in the output OFF
state.
• the short bit is set for shorted load and wiring conditions in the output
ON state.
• the reverse power bit is set for reverse polarity user power conditions.
• the module fault bit is set for any open, short, or reverse power conditions
detected.
The module’s diagnostic capability depends on whether the output is energized
(ON) or de-energized (OFF).
Fault Device/Output Status
Fault
Indicators
Error Bit
Status
Conditions
Field Device Status Output Status Module Fault Channel
Fault
Open OFF OFF Red Red Open wire
and Module
No current in output terminal-
missing dummy resistor or field device,
cut output channel or Common wire
OFF ON OFF Yellow None Can’t detect an open in the ON-state
Short OFF ON Red Red Short and Module Short - output to Common
OFF OFF OFF OFF None Can’t detect a short in the OFF-state
Reverse
User Power
OFF OFF or ON Red OFF Reverse and Module User power supply wiring is reversed
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