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I have OPLC V350-35-TA24 what includes onboard I/Os and configurable via wiring 2 Analog, 2 PT100/TC, and 1 HSC/ Shaft-encoder Input. So, first, i made changes in hardware project where analog input 2 and 3 were 0-10V, I connected them with potensiometer (i used voltage divider, so to analog input went 0,33-11,5 VDC, pot supply camed from same supply as OPLC +24VDC, pot signal went to analog input, pot ground went OPLC 0V). I also changed jumper setting, input 5 (analog input 3) - JP4 B, JP10 A, input 6 (analog input 2) - JP8 B, JP9 A. I made new project were was only linearization block: X1=0, X2=1000 (10V), Y1=0, Y2=16384, input MI0, output MI20. BUT in online test MI 0 was zero, I changed input voltage, but still, no numbers. Then I tested other analog input, same story !????

Today I changed analog input 2 (input 6) hardware configuration- 4-20 mA, jumper setting - JP8 B, JP9 B. Also, before inputs were PNP, now I changed them NPN source - JP12 A. 4-20 mA source I connected: plus into OPLC +V input and minus into analog input. In linearization block were: X1=0, X2=1000, Y1= 3277, Y2=16383, input MI 0, output MI100. BUT in online test MI0 were zero.

What Im doing wrong?!!

test 1903.vlp

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  • MVP 2023

Good job on a post with all the needed information!

You've got your X's and Y's backward. X is the input (raw analog) value, and Y is the output (scaled) value. I checked your program and the linear block is programmed right.

What kind of 4/20 source are you using? Is it a 2-wire transmitter simulator? If so, you connected it correctly. If your 4/20 source is a true current source then connect + to the analog input and - to 0V.

When you're having trouble with an analog input the first thing to do is check your sanity with a multimeter. Disconnect the input from AI 2 and measure the resistance from the input to 0V- if the jumpers are set right for current you should get 37 ohms. If this checks out, put your meter in current mode and insert the meter in series with the analog input to measure the actual current. If you don't have a valid electrical signal then the PLC will report nothing.

If it checks out electrically, go online and see if you get a raw value in MI 0.

Joe T.

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