The RevPi Compact has eight analog inputs and two analog outputs.
With each of the analog inputs you can measure a voltage between 0 and 10 V or perform an RTD measurement with a resistance temperature sensor (Pt100/1000). The analog input also serves as a constant current source. The Pt100/1000 sensor is connected directly to the analog input. Only a two-wire measurement is possible.
The MCP3550-50 analog-to-digital converter used for this purpose has a high resolution of 21 bits, but takes a comparatively long time, 85 milliseconds per measurement. Added to this are 40 milliseconds for switching the constant current source on and off and for switching the multiplexer, via which the eight inputs are connected to the ADC.
You can access the analog inputs either with piControl or without piControl:
With piControl, each input is read out with a cycle time of one second and stored in the process image as a 16-bit value in mV (for voltage measurement) or in 1/10 °C (for temperature measurement). Whether an input is used for voltage or temperature measurement is selected in PiCtory.
Without piControl, the cycle time for reading a single input is reduced to 125 milliseconds, and the raw value is available to you in full 21-bit resolution. From this raw data you can calculate the desired values yourself.
You can find out how to do this here.
Your RevPi Compact has two analog outputs. These outputs can output a voltage between 0 and 10 V. You can connect actuators such as frequency converters here.
The DAC082S085 digital/analog converter used for this purpose has a resolution of 8 bits.
Just as with the analog inputs, you can access the outputs either with piControl or without piControl: With piControl the outputs are updated from the process image with a cycle time of 250 µs. There you only have to store the desired voltage in mV. Without piControl you can update the outputs at any time. To do this, however, you have to calculate the raw value in 8-bit resolution from the desired voltage yourself.
There are three options for powering down the analog outputs: Terminated with 2.5 kΩ, with 100 kΩ or high impedance. The powerdown can only be used for both outputs together and only without piControl.