Rockwell Automation 1794-OB16D FLEX I/O Diagnostic Modules User Manual - Manual (Page 110)

Publication 1794-UM061A-EN-P - July 2006
108 Interpret the Indicators
Diagnostic Functions for the 1794-OB16D
Diagnostic Functions for the 1794-OB16D
ATTENTION
Each unused output port requires a dummy resistor
(20 K
Ω +10%, 1/8 W) to mask the channel diagnostic
function.
Ext.
Power
Wiring Output
Status
Channel LED
Status
Open Wire
Error Bit
Short
Error Bit
Rev. Error
Bit
Module Error
Bit/LED
OFF Open Off Off 0 0 0 0/OFF
On Off 0 0 0 0/OFF
Short Off Off 0 0 0 0/OFF
On Off 0 0 0 0/OFF
Normal Off Off 0 0 0 0/OFF
On Off 0 0 0 0/OFF
ON Open Off RED 1 0 0 1/RED
On YEL 0 0 0 0/OFF
Short Off Off 0 0 0 0/OFF
On RED 0 1 0 1/RED
Normal Off Off 0 0 0 0/OFF
On YEL 0 0 0 0/OFF
REV Open Off Off 0 0 1 1/RED
On Off 0 0 1 1/RED
Short Off Off 0 0 1 1/RED
On Off 0 0 1 1/RED
Normal Off Off 0 0 1 1/RED
On Off 0 0 1 1/RED
The module monitors each output channel. It turns on the channel red indicator and sets (1) the error bit when 1) the module detects a
short circuit (the output signal is active at a channel and the corresponding output voltage is low), and 2) the module detects an open wire
(the output signal is inactive at a channel and the corresponding output voltage is high).