Out-Of-Range Detection; Module Status Led (Green) - Allen-Bradley SLC 500 User Manual

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 13 (under-range) or 14 (over-range) of the channel
status word is set. Refer to the temperature ranges provided in the
table on page 5-9 for a review of the temperature range limitations for
your input device.
Possible causes of an out-of-range condition include:
• The temperature is too hot or too cold for the thermocouple
being used.
• A type B thermocouple may be registering a °F value in
engineering units x 1 that cannot be expressed by the data bits.
Refer to page 5-11 for more information.
• A CJC may be damaged or the temperature within the cabinet
containing the module may be outside the CJC range limits.

Module Status LED (Green)

The module status LED is used to indicate module-related diagnostic
or operating errors. These non-recoverable errors may be detected at
power-up or during module operation. Once in a module error state,
the thermocouple module no longer communicates with the SLC
processor. Channel states are disabled, and data words are cleared (0).
Failure of any diagnostic test results in a non-recoverable error and
requires the assistance of your local distributor or Rockwell
Automation.
Module Diagnostics and Troubleshooting
Publication 1746-UM007C-EN-P - July 2004
7-5