Re: [foxboro] HART on I/A -- thoughts?

Yes, the isolation issue is something I've heard a lot about.  It hasn't 
been an issue for me (yet), I guess because I use either loop-powered 
instruments or 4-wire instruments with isolated out;puts -- in other 
words, no common external power supply.  I still have some issues in one 
of my plants, though, so you never know.

Corey Clingo
BASF Corp.





"Dykes, John" <JDykes@xxxxxxxxxxx> 
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Re: [foxboro] HART on I/A -- thoughts?






The system alarm aspect is really a pain in the arse. 
I submitted a CAR about this last year and all I got 
was this lousy T-shirt....joshin'. The response was 
this is how the product is designed ...... this CAR 
is closed. I like the ability to "touch" most hart 
devices from afar and we had pretty good success with 
that and it did ease the startup of a new plant. The 
other issue I mentioned in the CAR was an observation. 
I seen a few occasions where a HART error would cause 
the downstream blocks to HOLD or TRACK with the setting 
of "NOFAIL". "NOFAIL" is not its descriptive function for 
sure. The 4-20mA was OK. Lack of descriptive errors and 
some type of logging is a hair puller.

As a side note and toward the decussion of FBM201 vs FBM214
The biggest thing to note is the issue of point to point 
isolation. You need to make sure this will not be an issue 
in your design.

Anyways....my two cents.

___________________________________
James J. H. Dykes
Tesoro Petroleum
Golden Eagle Refinery
Technical Services
Process Controls
150 Solano Way
Martinez Calif.
94553-1487

Phone:925.228.1220 Ext. 2930
E-mail:jdykes@xxxxxxxxxxx 

 



 
 
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