Using PLC for Custom-design of a PID/PWM Program to Control a Heater Temperature
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Copyright: © 2020 Mohammad A.K. Alia. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
This is a practical approach to control a continuous-time process variable (temperature) using a discrete controller (PLC) and a custom-designed software control algorithm and hardware interface, in a closed-loop system. Unlike the conventionally known technique of transforming a digital control action into a proportional analogue one by a D/A converter followed by power amplifier, the control action was formed internally by the PLC as a PID/PWM signal, which was used to trigger the power stage. This approach helped reducing the error due D/A conversion, maximized utilization of the PLC and reduced total cost. The control system is realized by utilizing the heater of the training board (RGT1), manufactured by DL-lorenzo Company and it simulates an analogue heating control system. The PLC is Siemens Simatic S7-214 model. An experimental result has shown that the control algorithm functions perfectly.
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- PID software program
- analogue input digital output
- interface board