Rockwell Automation 1794-OF8IH FLEX Isolated Input/Output HART Analog Modules - Manual (Page 17)

Publication 1794-UM065B-EN-E - September 2010
About the FLEX I/O HART Analog Module 5
However, the remote transmitter may be capable of diagnosing a problem in
the remote loop and signal the input module local loop with a preprogrammed
out of range (high or low) value.
The Fault Enable bit allows the 1794-IF8IH module to work with transmitters
like the one just described.
Use Remote Fault Alarm to Determine High-High or Low-Low Alarm Levels
If you do not have a remote transmitter in your loop, this alarm can also be
used to program a high-high or low-low alarm level between the levels which
actuate the overrange or underrange alarms and the high or low local fault
alarms.
Programming the Remote Fault Alarm
For the remote fault alarm, you must program the threshold in 0.1 mA steps at
any level on the high or low end of input signal range. The remote fault alarm
activates if your I/O module receives input signal values of:
• 100.63…111.88% (20.1…21.9 mA) on the high end of input signal
range
or
• -0.63…-11.88% (3.9…2.1 mA) on the low end of input signal range.
Local Fault Alarm
The local fault alarm notifies you when the loop to the transmitter or field
device, if no transmitter is used, is open or shorted.
• 112.50% (22 mA) or higher on the high end of input signal range.
This value indicates a short in the loop.
or
• -12.50% (2 mA) or lower on the low end of input signal range.
IMPORTANT
Once the alarm is issued, it remains active as long as the input signal
value remains above the programmed value.
IMPORTANT
Once the alarm is issued, it remains active as long as the input signal
value remains in the programmed range.