Rockwell Automation Publication 1794-UM061B-EN-P - March 2020
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About the FLEX I/O Diagnostic Input Module
Chapter
2
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, and channel wiring fault conditions:
–
Off indicates that the input channel is off with no faults.
–
Yellow indicates that 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)
