Rockwell Automation 1794-OB16D FLEX I/O Diagnostic Modules User Manual - Manual (Page 25)

Publication 1794-UM061A-EN-P - July 2006
About the FLEX I/O Diagnostic Input Module 23
User Power Supply Reverse Voltage Detection
If the external user power supply is miswired (incorrect polarity), 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 module’s 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.
Detection can be accomplished by wiring an input channel to the user supply.
Any 24V dc input can be used. You can wire a 1794-IB16D diagnostic input
module or 1794-IB16 input module to monitor the user supply as shown
below:
Indicator Status
Information
The 1794-IB16D diagnostic input module has indicators that let you check the
module health and operational status. The following status can be checked
with the indicators.
• Channel I/O Status - This indicator displays the ON/OFF state of the
input channel, as well as channel wiring fault conditions:
– Off indicates the input channel is off with no faults.
– Yellow indicates the input channel is on with no faults.
– Red indicates either a channel sensor power open or short condition.
• Module Fault Status- This indictor turns red for any individual input
channel open, short or module reverse power conditions.
With no fault, the module fault status indicator turns off.
(1794-IB16D shown)