A DIGITAL TEMPERATURE CONTROL-SYSTEM

The article outlines the hardware and software components of a general-purpose, PC-based temperature programming system. The multichannel thermocouple readout unit can switch, under computer control, among several modes of operation: calibration, analog cold junction compensation, differential temperature reading. The heating power is proportional to the output of a 12-bit DAC and is delivered by an efficient switching power supply. On the software side, we first introduce the development environment and the algorithms used to compute the control action. We show that an adaptive strategy outperforms the traditional proportional-integral-differential approach, and yields fast and accurate temperature responses when driving devices with widely different thermal characteristics.