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