Bench tank rig, CPU 1214C with an SM 1231 AI 4x13 bit, TIA V17. Channel 0 is configured as current, 0 to 20 mA, and the 4 mA offset is taken out in NORM_X.
I replaced the old 4-wire level transmitter with a 2-wire one, same 4 to 20 mA output, plus to channel 0 plus and minus to channel 0 minus, the way the old one was. Now the raw value just sits at 0. No wire break diagnostic, no underflow, just 0, where the old transmitter gave about 16700 at half tank. I checked the NORM_X and SCALE_X blocks and moved it to channel 1, still 0.
Why doesn't the module see the new transmitter when the old one worked on the same terminals? Pretty sure the difference is the 2-wire part, but I can't see what it needs that the old one didn't.
Two things it could be, and the module configuration isn't one of them since it worked before. Either the loop has no power in it, or the terminals are wrong for a 2-wire device. Post how it's wired, terminal by terminal, and put a meter in series to read the loop current.
Transmitter plus to 0+, transmitter minus to 0-, nothing else connected to it. Meter in series reads 0.0 mA. The old transmitter had four wires, two went to the 24V supply and two to the channel.