I am trying to debug a pressure transmitter that outputs a 4-20 mA signal. Currently , the value is changing on the HMI screen and PLC depending on how fast we run a VFD, but when i put my multimeter in series with the output of the sensor, i get a solid 6mA no matter what. I know the value is changing in the PLC, but why am i not getting fluctuation on my measured value in the meter? Am i missing something