EPICS Controls Argonne National Laboratory

Experimental Physics and
Industrial Control System

1994  1995  1996  1997  1998  1999  2000  2001  2002  2003  2004  <20052006  2007  2008  2009  2010  2011  2012  2013  2014  2015  2016  2017  2018  2019  2020  2021  2022  2023  2024  Index 1994  1995  1996  1997  1998  1999  2000  2001  2002  2003  2004  <20052006  2007  2008  2009  2010  2011  2012  2013  2014  2015  2016  2017  2018  2019  2020  2021  2022  2023  2024 
<== Date ==> <== Thread ==>

Subject: Re: Logarithmic conversion / Breakpoint tabes
From: Maren Purves <[email protected]>
To: [email protected]
Date: Tue, 29 Mar 2005 08:14:21 -1000
We also use a CALC record to take the logarithm and archive that.

Maren

Owens, PH (Peter) wrote:
I have some AIs like that.
I deal with the input using a CALC record
just as you suggest for your outputs.

Pete.

-----Original Message-----
From: Gavin Smith [mailto:[email protected]]
Sent: 29 March 2005 07:37
To: [email protected]
Subject: Logarithmic conversion / Breakpoint tabes


Hello All,


I have an Ai record which gets raw data from a pressure (vacuum?) sensor measured by the PLC. The raw data ranges from 0 to 256000 and represents a Torr of 1e-11 through to 1e-3. I am wanting to convert this into the engineering units, but as far as I can see only linear styles of conversion are supported. I could make a breaktable with some values in it, but if I understand correctly the gaps between the points will be interpolated linearly, and will therefore suffer some error.

In addition to inputs, I need to have a couple of Ao's, representing maximum allowable pressures, etc. My current thinking is to have a calc record for each sensor to evaluate something like CALC,"exp(A/3200-4)", and for the outputs having an ai feeding a calc feeding an ao record for each one.

How are other people handling this in their systems? Extra records, big breakpoint tables or some other way?

Thanks,
Gavin Smith.

(I'll be away from the office till next week sometime, so don't think I'm snubbing anyone by not replying to them straight away).




References:
RE: Logarithmic conversion / Breakpoint tabes Owens, PH (Peter)

Navigate by Date:
Prev: RE: Logarithmic conversion / Breakpoint tabes Dalesio, Leo `Bob`
Next: Re: Logarithmic conversion / Breakpoint tabes Brian McAllister
Index: 1994  1995  1996  1997  1998  1999  2000  2001  2002  2003  2004  <20052006  2007  2008  2009  2010  2011  2012  2013  2014  2015  2016  2017  2018  2019  2020  2021  2022  2023  2024 
Navigate by Thread:
Prev: RE: Logarithmic conversion / Breakpoint tabes Owens, PH (Peter)
Next: RE: Logarithmic conversion / Breakpoint tabes Mark Rivers
Index: 1994  1995  1996  1997  1998  1999  2000  2001  2002  2003  2004  <20052006  2007  2008  2009  2010  2011  2012  2013  2014  2015  2016  2017  2018  2019  2020  2021  2022  2023  2024 
ANJ, 02 Sep 2010 Valid HTML 4.01! · Home · News · About · Base · Modules · Extensions · Distributions · Download ·
· Search · EPICS V4 · IRMIS · Talk · Bugs · Documents · Links · Licensing ·