Temperature controllers accept inputs from temperature sensors such as thermocouples, PT100 RTDs and in some cases NTC thermistors. Process controllers accept temperature sensor input and also accept process signals like voltages and milliamps. All of our controllers offer simple on/off control and most offer the more sophisticated PID control including auto tune capability. Other useful features such as digital communications including USB, Modbus RS485 and Bluetooth are optionally available for certain models. When selecting a controller here are some terms of which you should be aware:
On/Off Control – A simple type of control in which the controller output changes as the process variable crosses the setpoint.
PID Control – A type of control in which the controller output is determined by an algorithm incorporating the distance of the measurement from the setpoint, the rate of change of the measurement and oscillations around the setpoint. PID control results in more precise control than ON/Off control.
Autotune – PID control requires adapting the PID algorithm to the actual process. Controllers with the autotune feature automatically adapt the PID algorithm to the process.
Hysteresis – Used with on off control. Hysteresis applies a bandwidth around the setpoint. With hysteresis, rather than the output turning on and off as the measurement fluctuates above and below a setpoint, hysteresis applies a range of values around the setpoint at which the output will turn on and off. Hysteresis is used to eliminate relay chatter and/or protect a connected devices from turning on and off rapidly.
Ramp and Soak - Allows a controller to change the setpoint at different times according to a preset profile.