Open Wire Detection - AI Channel blocks
The open wire diagnostic detects and annunciates broken field wires. In addition, a seemingly valid
PV from a channel diagnosed as having a broken-wire will not be made available (thus preventing
incorrect control action). Open Wire Detection is available with AI-HART module.
If open wire detection is enabled (OWDENBL = ON) and the IOM detects the broken-wire condition,
then
l Soft Failure 179 'Open Wire Detected' is generated, and
l PVRAW and PVAUTO will consequently be set to NaN.
ATTENTION
Open wire detection is not supported in AI-HART (Cx-PAIH51) module. The configuration
mismatch warning message appears when you select the OWDENBL option and loads
AICHANNEL FB to AI-HART (Cx-PAIH51) module. After loading the module, the channel can
be activated. However, the OWDENBL parameter value appears as 'FALSE.'
10.12.6 Checking and Filtering PV Range - AI Channel blocks
PV range checking ensures that the PVCALC output of PV characterization is within the limits
defined by parameters PVEXEULO and PVEXEUHI. If either of the limits is violated, the output of
the PVAUTO is set to NaN if clamping has not been specified. If clamping has been specified, the
output of the PVAUTO is clamped to PVEXEUHI or PVEXEULO, except when PVRAW, PVCALC, and
PVAUTO will consequently be set to NaN.
ATTENTION
Honeywell recommends you to configure the current for HLAI (CC-TAIX01) modules from -
6.9% to +102.9% of the 4-to-20 mA range. If you configure the current above +102.9% then
the PVEXEUHI goes to NaN.
If the range-checked and filtered value is less than the value specified by the user-configured
LOCUTOFF parameter, the final output called PVAUTO is forced to PVEULO.
