Rockwell Automation Publication 1794-UM061B-EN-P - March 2020
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About the FLEX I/O Diagnostic Output Module
Chapter
3
External Power Supply Reverse Voltage
If the external user power supply polarity is incorrect, the module is protected
and reports a reverse user voltage fault. The reverse voltage condition must be at
least -10V to detect a fault. The modules fault indicator turns red and the reverse
fault bit is set. The module error bit is also set. When the correct user power
supply polarity is applied, the module Fault indicator is off and the reverse fault
bit is not set.
User Power Supply Loss Detection
The module does not check for presence of the external user power supply. You
can detect user power loss by wiring any spare 24V DC input on a 1794-IB16D
input module or 1794-IB16 input module to the power leads of the power supply
for the 1794-OB16D.
Output Fault and Idle States With Network Communication
Failure
Configure module outputs for fault states, (either all on, all off or Hold Last
State), in the event of a network communication failure (fault state) or switchover
to Program mode (idle state). For example, if your module is configured so that
the state of the outputs turns off during Program (idle) mode, any on-state
outputs will turn off when in idle mode (processor keyswitch placed in Program
mode). See documentation for your FLEX I/O adapter and associated processor
or controller for further information.
Indicator Status Information
The 1794-OB16D diagnostic output module has status indicators that allow you
to check the module health and operational status.
(1794-IB16D shown)
