AIO connection with pressure passive sensor

[luigi.rusconi]

Hello,

I'm trying to connect a pressure sensor with just 2 wires (https://www.ifm.com/nl/en/product/PT5401) with the AIO card but until now I couldn't find a solution.
I've followed the tutorial (https://revolution.kunbus.com/tutorials ... revpi-aio/) but at the moment I don't know how to perform this connection (everytime I obtained errors and I couldn't measure anytihing).

How can I solve this issue? Is there any connection solution for passive sensors with 2 wires with the AIO card?

Thanks.


Luigi

[Eduard]

Hello Luigi,
please connect the sensor to the IN 1 interface. Pin 1 (brown) of the sensor must be connected to pin 28 of the AIO. Pi 2 (white) of the sensor must be connected to pin 24 of the AIO and since it is a current sensor you have to connect pin 28 and 26 to each other.
Next do the following configuration in piCtory:

piCtoryConf.jpg (10.02 KiB) Viewed 7145 times

Now you have to save the configuration "Save as Start-Config." and "Reset Driver". Now you can query the measured value of the sensor with “piTest -r InputValue_1”.

Best regards
Eduard

[luigi.rusconi]

Thanks for the advice Eduard.

Unfortunately this configuration was the one that I did at the first time, but I had the flashing red LED about the supply for the input.
I solved using an external power supply of 24 VDC connecting in series the sensor and the Analog Input of the Rev Pi.
So now I’ m wondering if it is possible to connect directly with AIO a passive sensor, without external power supply (as it is possible with the RTD input I guess). This is a feature of the active cards.
Is there a way to exploit this connection also with the AIO of the Rev PI or it has got just passive AIO?

Thanks

Luigi

[Eduard]

Hello Luigi,
you're right we have only passive inputs, so my first explanation is also wrong.
Thank you for your correction.

As you already wrote, you have to connect an external power supply to the sensor.
And connect the sensor and the analog input of the AIO card in series.

AIO_RevPi.jpg (10.7 KiB) Viewed 7008 times

So you have to connect 24V to the pin1 (brown) of the sensor. The pin2 (white) of the sensor must be connected to pin 28 of the AIO card.
Pin 24 of the AIO card must be connected to GND and since it is a current measurement pin 28 must be connected to pin 26.