adccommunitymod (AutomationDirect) asked a question.
Analog Input problem
Created Date: March 10,2016
Created By: jtak101
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I have analog input card F2-04AD-2, using an Ashcroft pressure transducer Range is 0/500psi, Input 1-5VDC, Supply 9-36VDC... The issue I am having is when the system has no pressure I am reading 819 in the PLC, so with my scaling it displaying 100psi on the panel... When I take the transducer and connect -V common with +V output I do read 500 on the panel, and 4095 in the PLC... at a complete loss, any help would be appreciated, thank you
Created Date: March 10,2016
Created by: Tinker
1-5V looks much like 4-20mA, they presumably don't start at zero so that open connections can be detected. You just need to subtract that 819 before you do your scaling, then you would scale for a 4V span (multiply by about 0.153)
Created Date: March 10,2016
Created by: jtak101
1-5V looks much like 4-20mA, they presumably don't start at zero so that open connections can be detected. You just need to subtract that 819 before you do your scaling, then you would scale for a 4V span (multiply by about 0.153)
Okay, so in my logic I now have:
LD V2001
MUL K500
DIV 4095
OUT V2012
I am a little confused on the scaling for 4V span, The only way I scaled was with the psi rating, So If I understand what your are saying it would change to:
LD V2001
SUB 819
MUL .153
MUL K500
DIV 4095
OUT V2012
Thanks for the response!
Created Date: March 10,2016
Created by: scott.lawrence
you need to scale the transducer for your display.... is this from the other post?
either way, the value you 're trying to get is 0-500, and the value you have is 0-4095.
since you have a 250-1 processor, you can use an I-Box (SCALEB) to scale the input to your desired output.
Created Date: March 10,2016
Created by: jtak101
you need to scale the transducer for your display.... is this from the other post?.
Yes, this is a continuation of that, same application I resolved that thanks to your help I can now lock the highest pressure on the display
since you have a 250-1 processor, you can use an I-Box (SCALEB) to scale the input to your desired output.
I have never used the I-Box (SCALEB) function before, so is the math I have then is no longer needed? I will look into that I-Box function now.
Created Date: March 10,2016
Created by: scott.lawrence
the SCALEB is doing the math for you behind the scene , so to speak.
Created Date: March 10,2016
Created by: jtak101
the SCALEB is doing the math for you behind the scene , so to speak.
Okay so I can delete my math, then use the Ibox which I read the help menu so for my application would look like this?:
Raw (12 bit binary) -- V2001
High Engineering -- K4095
Low Engineering -- K0
Engineering Binary -- V2011
Created Date: March 10,2016
Created by: scott.lawrence
raw is the location of the raw analog input.
engineering units are the output you want, so in your case, the high/low would be 500/0 for the PSI of the device.
engineering binary is where the scaled data will be placed.
Created Date: March 10,2016
Created by: jtak101
I meant 500 on the engineering high units, okay perfect will put this in now and test it out, thank you... again!
Created Date: March 10,2016
Created by: Tinker
you need to scale the transducer for your display.... is this from the other post?
either way, the value you 're trying to get is 0-500, and the value you have is 0-4095.
since you have a 250-1 processor, you can use an I-Box (SCALEB) to scale the input to your desired output.
Actually, since the transducer is 1-5V I think he has an input of 819-4095 which he needs to scale to 0-500. I have not used Direct soft to any extent, certainly not the SCALEB, can it take a negative number for scale low? since 500/(5-1) = 125 per volt, I'd think that a scale low of -125 and scale high of 500 should give 0(psi) for 1 volt and 500(psi) for 5V ? a negative 125 psi would indicate an open circuit.
Created Date: March 10,2016
Created by: scott.lawrence
Actually, since the transducer is 1-5V I think he has an input of 819-4095
I didn't even catch that... but the SCALEB has In Min/Max as well as Out Min/Max that OP can enter 819-4095 for the In Min/Max, and 0-500 for the Out Min/Max