Process control systems are centered on a Raspberry Pi 4,5 single board computer. Smaller systems attach directly to the Pi's 40 pin IDC header, in the style of a "hat".
These controller boards work at voltage levels of a few volts. However we go to higher current or voltage with external add-on electronic boards, to match a variety of standard industrial interfaces (e.g. Opto22). Typical data acquisition IC's include: AD5592, LTC2418.
Smaller system, configured as a "hat" for a Raspberry Pi:
o analog digital converters
10K sample/sec AD5592, 12 bit, up to five differential ADC inputs, buffered by an instrumentation amplifier INA821
1 sample/sec LTC2418, 24 bit, up to ten single ended or 5 differential ADC inputs, software configurable
o digital to analog converters
1 KHz AD5592, 12 bit, one operational amplifier buffered digital-to-analog converter output
multiple ways to configure six low current dac outputs
o general purpose digital input and output
Six digital inputs, 2 digital outputs, each buffered for higher current and isolation (74HCT645).
Larger system: (RAS_1021_Controller_sensor_tests)
o analog to digital converters
10K samples/sec AD5592, 12 bit, qty 8 ADC inputs, typical few volts unipolar input, op amp buffered
1 sample/sec LTC2418 24 bit, 24 channels of ADC input, software configurable for few volts single ended or differential input, input over voltage, electrostatic protected for use in harsh signal conditions.
o digital to analog converters
1Hz AD5592, 12 bit, qty 5 high current buffered, analog outputs
o general purpose digital inputs and outputs, all buffered or over voltage protected
Qty 24 digital inputs, qty 15 digital outputs.
A very basic design example: LTC2418, 24 bit ADC:
raspberry pi hat, circuit board mounted on top of single board computer