Scaling 1794-ie8 in L75 processor

Boo

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Join Date
Feb 2020
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mo
Posts
3
I am trying to scale an analog input for 4-20ma. Rockwell's website says that 0-30840 are the proper numbers. But the unscaled input raw is already 32738. When I scale the raw max at the 30840 I get an out_pv of 106.15 which I know is not the current temp.
 
I suggest you post this in the Live Q&A as most do not read this area
Edit: 32768 is -0 as 32767 is max for 16 bit word you need to read it as an integer so you get negative values
32767 = +0 32768 = -0.
 
Last edited:
Yes it does equal 21 ma which I have learned is the default alarm condition for the Rosemount 644 transmitter that is connected to this card. The input raw was coming in at the 21ma which signaled that the transmitter was unhappy. I rescaled the input and then cycled the power. It is reading correctly now.
thank you all for your input. I have referenced this site for years and finally decided to become a member. The knowledge base here is fantastic.
 

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