FactoryTalk View / Compactlogix Changing 0.000 - 0.630 on Display to -0.315 to +0.315

[Baker in Virginia]

Good Morning ,

On my Panelview Plus ( CompactLogix ) I have a knife position that is showing 0.000 to 0.630 on my HMI and also my program . I took notice
that this knife postion goes below the center line , so I would like to display
this number as -0.315 to +0.315 . I don't have any adjustment on my Linear Position Sensor. What would be the best way to make 0.000 to 0.630 show as -0.315 to +0.315 on my HMI ?

I know there are some instructions to invert a value , but this is under and above the centerline .

Thanks so much again for your help.

 

[janner_10]

Adjust the value in the PLC and read that adjusted value tag on the HMI.

 

[Baker in Virginia]

Thanks . That is what I was planning on doing , but how would you modify that code to come up with the desired value .

 

[cwal61]

If you search SCL in the help file it will show you the formula to use. I just tried it with the CPT instruction and got the results you wanted.

I Created the following REAL tags but you could hard code it in the formula if you parameters are not going to change.
IN = Value coming from device
RawMin = 0
RawMax = .63
EuMin = -.315
EuMax = .315

Expression in the Compute instruction was this ((IN-RawMin)*((EUMax-EUMin)/(RawMax-RawMin)))+EUMin

Hardcode is this (IN-0.0)*(.315 - -.315)/(.63-0.0)+ -.315

 

[cwal61]

Minimum hard coded results

Maximum hard coded results

 

[Baker in Virginia]

Thanks so much for taking the time to try this code out.

So you are saying that the following expression will take the 0.000 to .630
and allow that to scale -.315 to 0.00 and from 0.00 to +.315 ? The journey of the magnet will cover this span.
---------------------------------------------------------------------------------------
Expression in the Compute instruction was this ((IN-RawMin)*((EUMax-EUMin)/(RawMax-RawMin)))+EUMin.

I Created the following REAL tags but you could hard code it in the formula if you parameters are not going to change.
IN = Value coming from device
RawMin = 0
RawMax = .63
EuMin = -.315
EuMax = .315

 

[rdrast]

If it is just a fixed value, just subtract 0.315 from the input.

 

[daba]

If it is just a fixed value, just subtract 0.315 from the input.

+1


No scaling needed

 

[Baker in Virginia]

Thanks . It will be always changing . It is a linear position sensor with a magnet .

 

[daba]

Thanks . It will be always changing . It is a linear position sensor with a magnet .

If it is continually changing between 0.0 to 0.630, then subtracting 0.315 will give you -0.315 to +0.315, which is, I believe, what you asked for on the HMI.