4-20mA Current Loop Transmitter: Help

I am using the 1-Channel Isolated 4-20mA Current Loop Transmitter With Power Supply (PR33-49) I want to control pressure control valve. I measure 36mA output Signal. I dont thinkt the transmitter is malfunctioning I ordered 3 and everytime its the same problem.
I control the loop transmitter with a raspberry Pi.
Any help or advice is greatly appreciated, thanks!

36mA is theoretically impossible give thant its range is limited to 22mA.

  1. can you measure voltage across the terminals
  2. can you share a picture of your setup

Voltage is 12V
The Red abd the Blue cable are going directly to control the pressure valve

  1. are you powering the board using 3.3V or 5V. you should be using 5V.
  2. RPI does not have any i2c pull ups , so you should be installing on board pull up jumpers
  3. remove any connection from the board and measure current across the two terminal as well.


  1. Yes I am Powering the board with 5V
  2. What do you mean with install Pull up jumpers?
  3. the output ist 36mA

you need this rpi shield

Hmm Okay… but this device does the same like i did with the jumper wires? it is just connecting the RPI with the current loop transmitter…

Im also not sure what exactly the I2C Adress Jumper does und the Pull-Up Jumpers?

RPI i2c is 3.3v and the 4-20mA board runs at 5V.

Yes, thank you that seems to be the problem… Does the rpi shield you recommended solve the problem?