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Analog inputs

Analog inputs (AI) are for measuring analog values such as DC voltage, current and resistance. These values are produced by sensors which indicate multiple states such as thermometers, tensometers, distance meters, luxmeters etc.

The functionality of AIs on Neuron and Axon is different on Group 1 and Group 2/3 and on Neuron extensions.

On Group 1, the analog input is capable of:

  • measuring 0-10V DC
  • measuring 0-20mA DC

The Group 1 is also capable of measuring the resistance, but this is achievable with Analog output.

On Group 2 and 3 and on the Neuron extensions, the analog input is capable of:

  • measuring 0-10V DC
  • measuring 0-2.5V DC with higher precision
  • measuring of 0-20mA DC
  • measuring of resistance 0-100kOhm via 2-wire method
  • measuring of resistance 0-2kOhm via more precise 3-wire method

Changing between modes depends on the software you are using, please follow the relevant tutorial.

Measuring voltage

Measuring current

Measuring resistance

The UniPi 1.1 has two analog inputs and they are only capable of measuring voltage in a range of 0-10V DC.

Measuring resistance

To measure resistance from the UniPi 1.1's AI (ie. by using PT1000 thermal probes), it is necessary to add a resistor according to the following scheme.

R_sens = the sensor itself R_ref = the resistor

For reading temperature between 200-3800R (-200°C/+800°C), a 1K resistor should be used to ensure the voltage will not exceed 10V.

The value at the AI is calculated using the following formula R_sens (200) = 12V/969.7 + 200)*969.7 = 9.948 R_sens (3800) = 12V/(969.7+3800)*969.7 = 2.439