Error Reading a negative value with Read Input S16 (4)

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Well I'm reading a metering value that is expected to be sometimes negative, I'm using Read Input S16 (4) to do so, and the value I'm reading is ie.


should be:




should be


I've made some calculations and found that if I subtract a constant value of


I get the value I was expecting.

So I wrote the event of my channel






I was trying to use a CONVERSION but it does seem that I can't use IF in my FORMULA.

Anyways let me know if what I'm doing is ok or I'm doing something wrong in the I/O type of my channel.


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Thanks the inline "if" works just fine, however I've changed the IO Type to Read Input S32 R Words (4) and it seems to be working ok.

I will ask the device manufacturer about it's comm standards and let you know.

thanks again.

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Are your values actually 32 bit values (i.e. use two registers)? If not, then you probably just got lucky that it worked, likely because the negative bit got moved into a different register that happened to be 0. It will likely stop working when the adjacent register changes value. Just because it worked now doesn't mean its right.

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