Channel Diagnostics; Invalid Channel Configuration Detection; Over Or Under Range Detection; Open Circuit Detection - Spectrum Controls 1769 User Manual

Channel
Diagnostics
Non-critical vs.
Critical Module
Errors
Chapter 4: Diagnostics and Troubleshooting
When an input channel is enabled, the module performs a diagnostic check to see
that the channel has been properly configured. In addition, the channel is tested
on every scan for configuration errors, over-range and under-range, and open-
circuit conditions.

4.4.1 Invalid Channel Configuration Detection

Whenever a channel configuration word is improperly defined, the module
reports an error. See a description of module errors later in this chapter.

4.4.2 Over or Under Range Detection

Whenever the data received at the channel word is out of the defined operating
range, an over-range or under-range error is indicated in input data word 7.
Possible causes of an out-of-range condition include:
• The temperature is too hot or too cold for the type of RTD being used.
• The wrong RTD is being used for the input type selected, or for the
configuration that was programmed.
• The input device is faulty.
• The signal input from the input device is beyond the scaling range.

4.4.3 Open Circuit Detection

On each scan, the module performs an open-circuit test on all enabled channels.
Whenever an open-circuit condition occurs, the open-circuit bit for that channel
is set in input data word 6.
Possible causes of an open circuit include:
• The input device is broken.
• A wire is loose or cut.
• The input device is not installed on the configured channel.
• A RTD is installed incorrectly.
Non-critical module errors are typically recoverable. Channel errors (over-range
or under-range errors) are non-critical. Non-critical error conditions are indicated
in the module input data table.
Critical module errors are conditions that may prevent normal or recoverable
operation of the system. When these types of errors occur, the system typically
leaves the run or program mode of operation until the error can be dealt with.
Critical module errors are indicated in Extended Error Codes.
User's Manual Pub. 0300241-02 Rev. A
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