Rockwell Automation 1746-NR4 SLC RTD/Resistance Input Module User Manual - Manual (Page 103)

Publication 1746-UM008B-EN-P - December 2006
Module Diagnostics and Troubleshooting 103
Open- and Short-circuit Detection
An open- or short-circuit test is performed on all enabled channels on
each scan. Whenever an open-circuit or short-circuit condition occurs,
the channel LED indicator blinks and bit 13 of the channel status word
is set.
These are possible causes of an open or short circuit.
• The RTD or potentiometer may be broken.
• A RTD or potentiometer wire may be loose or cut.
• The RTD or potentiometer may not have been installed on the
configured channel.
• The RTD may be internally shorted.
• The RTD may be installed incorrectly.
If an open or short-circuit is detected, the channel data word reflects
input data as defined by the broken input configuration bits (6 and 7)
in the channel configuration word.
Out-of-range Detection
Whenever the data received at the channel data word is out of the
defined operating range, an over range or under range error is
indicated and bit 14 of the channel status word is set.
For a review of the temperature range or resistance range limitations
for your input device, refer to the temperature ranges provided in the
tables on page 72…73 or the user-specified range in configuration
words 4…7 if proportional counts is used.
IMPORTANT
There is no under range error for a direct resistance input
(default scaling).