We are facing issues with HART enabled Analog Output channels. This is for a specific manufacturer only (Metso Automation ND9000H). At random time intervals, the channels are going to BAD status and AO function block mode goes to IMAN mode. This gets cleared only after HART alarms are cleared and then either redundant card is switched over or "Clear saved fault information" command is given. Customer requirement is even if HART alarms are received, the 4-20mA loop should not go BAD. When the channel is changed to Non-HART Analog output channel, no issues of valve going in IMAN are observed. DeltaV version is R5.1.
P.S:- The positioner installed has HART DD File Rev-4 but Rev-4 DD File is not available for R5.1 revision hence the channel cannot be autosensed in DVExplorer.
In reply to Tinh Phan:
In reply to Muzammil Shaikh:
Did you check the DC voltage at the DEVICE terminals?
Check for noise on the cable interfering with the HART signal. You can use a multimeter set to AC
Noise Level (pk-pk)
Noise Level (True RMS for sine-wave)
Rating
< 3 mV
< 1 mV
Excellent
3-30 mV
1-10 mV
Good
30-55 mV
10-20 mV
Fair
> 55 mV
> 20 mV
Poor
You can also use a portable scope to see if there is noise