What is a PID and why do we need it
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PID (proportional-integral-derivative), means processor control parameters designed and meant to keep a user (operator) defined process setpoint (SP) within a narrow allowable bandwidth (range) adjusting to changing environmental temps or pressures or other measures as quickly or as slowly as needed not to overshoot or undershoot the setpoint, therefore, providing a smoother more stable process value (PV).
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It is a closed-loop system. The system does a process and a measurement is taken after every piece and if the measurement is at the upper or lower limit an adjustment is automatic to bring back the measurement into the middle of the specification.
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ST (self-tuning) is that finds PID constants by using step response tuning (SRT) when Controller operation begins or when the setpoint is changed. Once the PID constants have been calculated, ST is not executed when the next control operation is started as long as the setpoint remains unchanged. When the ST function is in operation, be sure to turn ON the power supply of the load connected to the control output simultaneously with or before starting the Controller operation.