4-20mA receiver PR33-10 interfacing with externally powered sensor

I’m trying to connect an IR temperature sensor (PC151MT-0) to the PR33-10 as in the following picture, but when I follow that connection, I don’t get a good result (~0.07mA)

If I omit the external power supply I do get the results.
What would be the correct way to connect multiple sensors with external power?

Additionally, I’ve noticed differences in the measurements based on which channel I have the sensor connected to. If I leave the inputs floating, I get the following:
In1: 0.034mA
In2: 0.051mA
In3: 0.174mA
In4: 0.072mA
And with the temperature sensor I get the following differences:
In1: 5.531mA
In4: 5.489mA

These differences of 100uA or less shouldn’t be an issue for the measurements but I just want to confirm that this is expected.

the parts tolerance is around ±2%.


Thanks for the quick response.
Could you please take a look at the first part of the question about connecting an externally powered sensor?

can you share a picture of the board ?
it should NOT work without external loop power.

Hi Bhaskar,

I’ve tested different configurations since it seems the PR33-10’s 16V in the IN1 pin can power the sensor.
For options c and d, an external 16V supply was used

Options a and c, give reasonable results (5.4mA corresponding to ~22 C).
Options b and d give results similar to when there is nothing connected to the inputs (between 50 and 150 uA).

The issue that I’m having is that following the sensor’s manufacturer instructions (attached below), option d, looks more correct, with the power supply’s negative, connected to the - (G) of the measuring device, the supply’s positive to PWR+, and the measuring device’s + (IN1) to PWR-, where the 4-20mA signal is present, but this setup doesn’t work as expected.

Is it ok to rely on the internal boost as in case a and if using an external supply, do you have any suggestions on how to connect it, considering that more than 1 channel will be used simultaneously?

Apologies my bad. i didnt realize that you are using PR33-10. this board provides the loop power supply and does NOT need external power supply.
Yes, you can use multiple sensor and supply will be able to provide power to those.

Thanks for clarifying this.
One last question, the system is battery-based, so I am enabling power to the PR33-10 only when I need to measure. What is the minimum delay required after providing power, so the boost reaches its stable voltage?

I will recommend 3 sec + the sensor boot time if there is any.

Hi Bhaskar,

After going back and forth with our customer, they want to keep the sensors powered externally with 24v.
They connected it as in the image below and are always getting a reading 0mA , even though they can measure valid values with a multimeter(11mA) on the line.

The actual sensor being used is PX3234 and the following picture shows their wiring diagram
What would be the right way of connecting the PR33-10 to multiple sensors being powered externally?

this wont work.
for external power you will need this one

here if how you can modify the board you have