Using the Analog inputs

Topics about the Hardware of Revolution Pi
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thestumbler
Posts: 7
Joined: 10 Dec 2019, 00:41

Using the Analog inputs

Post by thestumbler »

Hello,

I can't seem to get rid of that flashing input light. I have a two wire analog sensor connected to input 1 on the rev pi. I have connected positive to 26 and 28, and negative to 24. The input is configured for 4-20ma. When I test this input using an onboard revpi output, it works fine, but won't work with my external sensor. Help is much appreciated.
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RR4711
Posts: 229
Joined: 22 Feb 2018, 13:28

Re: Using the Analog inputs

Post by RR4711 »

Been there... Done the same mistake....

You mostly assume (like I did) that the RevPi AIO supplies the sensor with the necessary +24V BIAS voltage which is not the case. It really only measures current. So you have to connect the plus wire of your sensor to the +24V supply, and the negative wire to the current (+) input on the RevPi AIO and the PSU GND to the (-) input of the AIO.

The documentation is a bit vague in that perspective....

Markus
h2oil
Posts: 10
Joined: 17 Jan 2020, 17:30

Re: Using the Analog inputs

Post by h2oil »

In regards to this where would the + and minus of the transducer be?

Kind Regards

James
RR4711 wrote: 11 Dec 2019, 13:45 Been there... Done the same mistake....

You mostly assume (like I did) that the RevPi AIO supplies the sensor with the necessary +24V BIAS voltage which is not the case. It really only measures current. So you have to connect the plus wire of your sensor to the +24V supply, and the negative wire to the current (+) input on the RevPi AIO and the PSU GND to the (-) input of the AIO.

The documentation is a bit vague in that perspective....

Markus
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RR4711
Posts: 229
Joined: 22 Feb 2018, 13:28

Re: Using the Analog inputs

Post by RR4711 »

Read my answer again. It‘s written there...
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