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Re: Is using HART digital mA to calibrate valid?

Message posted by Romilly Bowden (romilly@romilly.co.uk : 212.126.135.162) on 06 July 2002 at 21:00:47.

in reply to: Is using HART digital mA to calibrate valid? posted by Peter McCormack on 05 July 2002 at 16:53:18.

The procedure you describe doesn't fully calibrate a HART device, Peter.

Take a look at a fine article by Ken Holladay at http://www.thehartbook.com/articles/h8calibrating.asp .

The thing is, you should do the input (sensor to digital) and the output (digital to analogue) separately.

It's quite likely AMS or another HART host will read the digital PV value (HART command 1, or 3) so you want to get it right.

The 275 handheld communicator can help you do most of this, except it can't read the actual analogue output current.
Maybe your DCS can do that, or you just trust it with the conversion to eng. units.

Regards,
Romilly.




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