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Having an issue getting 4-20mA sensors to read on a V350-35-r34.


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So after a lot of troubleshooting I'm officially out of ideas, so hopefully someone can see what I'm missing. My current set up is 2 4-20mA pressure sensors hooked up to the 2 analog inputs on the V350-35-r34. Wiring is + to PLC input, - to power supply 0v which is commoned with the PLC, ground to ground. The jumper setup is A A B B B from 1-5, so just the analog jumpers changed over.

I have tested literally every aspect of this setup, both sensors are a complete loop when tested, the PLC reads correctly if I use a 4-20mA loop simulator, all the wires are intact, I've tested it at the minimum distance of the wires, I've used 2 different PLCs, I've quadruple checked the program and all of that setup. I have literally no idea what is wrong at this point. Is there anything else anyone can think of to test or troubleshoot with this?

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  • MVP 2021

If your transmitters are two wire devices (loop powered) you have to hook + of the transmitter to +24V, - of the transmitter to the + PLC inputs.

All that's connected to the + PLC input is a resistor to COM.  Your transmitter provides the current that then provides a voltage to the PLC's A/D converter.

Joe T.

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