I am writing to find out if other people have experienced this issue. We currently have a DeltaV 12.3 installation and are running AMS Device Manager 12.5 trying to use HART CHARMs to manage HART devices. We have experienced several incidents where we had a module go to MODBAD because of a bad input or output on a HART CHARM (after it has been working for months or years) with no diagnosable cause (checking the HART device with AMS Manager works and the HART device will not show errors, connecting with a HART field communicator to the device will also not yield any alarms or reasons for the issue, changing the CHARM will not change the outcome, download of the CHARM or the dependent module will not change the MODBAD situation). When changing the HART input or output to a normal 4-20 mA input or output, everything will function like it should.
Does anybody have any insight as to what the cause for such a failure would be.
These issues have caused process shutdowns or downtimes in our plant and I would really like to continue to use the AMS Device Manager over CHARMs for commissioning and troubleshooting if possible, rather than changing all HART CHARMs to simple 4-20mA inputs or outputs.
Regards
Frank
In reply to Tinh Phan:
Agree with Tinh 4-20 mA preferred for control and alarms and such. Using HART for continuous upgrade requires "digital grade" installation such as correct cable shield connection, isolation, and grounding. The installation can degrade over time if care is not taken when replacing devices, due to water ingress, or other changes. There could be intermittent comms issues. You can check comms health from DeltaV diagnostics.
Or
If you spot comms errors, you may want to check if installation has been damaged over the years
These stats may have been running since the system was commissioned so you may wish to reset these statistics, and then check back a few days later.
Stay safe,
Jonas
In reply to Jonas Berge:
Andre Dicaire
In reply to Andre Dicaire: