The Industrial Raspberry Pi Forum

I'm trying to hook up an analog distance sensor to the AIO module, and I'm having trouble.

The sensor sensor I purchased operates at 24 volts and outputs 0-10V. I'm having trouble figuring out how to hook it up

Here's what I've tried:

1) Hook up positive (brown) sensor wire to pin 27, negative (blue) sensor wire to pin 23, and black (signal) wire to pin 25.



Result: The sensor doesn't power on. I assume this is because the AIO module isn't providing the 24V necessary to power up the sensor.



2) Use the same setup as before, but additionally connect positive (brown) wire to power supply positive terminal and connect negative (blue) wire to power supply negative terminal

Result: Flashing red IN light on AIO module. I would assume this is because the power supply is over supplying voltage to the AIO.

Can you provide any suggestions for correctly wiring this up?

Thanks in advance.

Sorry for not having translated the full series of tutorials for AIO into English yet. It would have been much clearer. But let's take what we already have;
- negative input for current or voltage measurement channel 2
+ positive input for current or voltage measurement channel 2
* a jumper must be installed from here to pin 27 for current measurements

1) So from the last sentence for the "*" terminal you should understand that this terminal is only used for current input. As you have a voltage output (0-10V) this terminal is not to be used for your sensor.
2) As we have full differnetial inputs it should be clear that "+" and "-" are the positive and negative signal input. E.g. if you connect a 3 V voltage source between them your AIO will measure 3V. if you connect the positive end of the voltage source to "+" and the negative to "-" you will measure +3 V . If you reverse that you will get -3 V. Easy, isn't it?
3) Now to your sensor. If you read the sensor's manual or connection schematic you will find that such sensors normally have 3 wires: 2 are for current supply and normally marked as +(24V) and GND. You need to connect them to your power supply in order to power up your sensor. This could be a complete different power supply than the one you are using for the AIO as we have fully isolated and fully differential inputs. The third wire is the analog signal output of the sensor (in your case a 0 to 10 V signal) which is referenced to the GND potential. This means you connect the signal output to the positive AIO input and the GND reference of the sensor to the negative input of the AOI. That's all...

I hope this helps and you will succeed...

Thank you! I'm now receiving values from the sensor.

The voltage range of the sensor is 0-10v. The piTest tool reports values between 57 and1888 (0.057v- 1.888v, I assume). Is this the result of "parasitic resistors" described in your documentation? Are these values what I should expect on this system with a voltage output sensor?

57 for lowest value (57 mV) is absolutely okay. This is 0.57% Offset which is a normal value for sensors.
1888 mV is a wrong reading for a sensor with 0-10 V and full scale value. Ether you do not have a full scale input of the physical value or there is a damage of the sensor or input channel. Try using the second channel just in case...
Proximity sensors (utrasonic type) do have a stray angle. You must point to free air to get the full scale value. Nothing should be left or right of the sensor's front in a 100° range. please also read the sensor's instruction and the output range for the physical distances allowed.

User error!

It was a wiring issue with the sensor. It's now reporting between the expected 0-10 volts, and the system is working nicely.

Thank you for all your help.

You're welcome, goog things are running now!

Hi...as per my knowledge such sensors normally have 3 wires: 2 are for current supply and normally marked as +(24V) and GND. You need to connect them to your power supply in order to power up your sensor. This could be a complete different power supply than the one you are using for the AIO as we have fully isolated and fully differential inputs.

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