Connection RTD transducer with M12 plug

[Robbya]

Hi,

We are using a NI 9219 to connect to endress-hauser RTD's to labview. Those RTD's (https://portal.endress.com/wa001/dla/50003007130/000/05/TI123ren_1209.pdf) are 4 wire but they are deliverd with a M12 plug with following formation.

Pos. A: with electronics, M12 plug, 4-pin (see attachment)
Pin 1: power supply 10 to 35 V DC; current output 4 to 20 mA (cable connection, wire color brown = BN)
Pin 2: connection of PC configuration cable - shortened pin (cable connection, wire color white = WH)
Pin 3: power supply 0 V DC; current output 4 to 20 mA (cable connection, wire color blue = BU)
Pin 4: connection of PC configuration cable - shortened pin (cable connection, wire color black = BK)

How do I connect this device? Is it just a 4 wire configuration or a 2 wire because you have 2 pc connections?

Please Help,

Best regards,

Robby

[ThiCop]

Hello Robby,

In the passive case (Pos B: no electronics) this RTD can be easily measured as a 4 wire RTD in PT-100 Mode.

In Pos. B the explanation in the pdf seems to indicate something else.

They mention that in that case some electronic circuitry is used to create an analog, temperature-linear 4 to 20 mA output signal.

In this case you should not measure it the same way as a classic 4-wire or 2-wire RTD.

It seems like they expect you to do a Current measurement between pin 2 and 4. This can also be done with the 9219.

You also have to connect the other 2 pins to a DC-voltage source.