Chapter 15. The PID functions
15-1
15 The PID functions
15.1 Introductions
This chapter will provide information about the built-in PID (Proportional Integral
Differential) function of B and C type CPU module. (GM6 -CPUB and GM6 -CPUC) The
GM6 series does not have separated PID module like GM3 and GM4 series, and the PID
function is integrated into the CPU module (B and C type)
The PID control means a control action in order to keep the object at a set value (SV). It
compares the SV with a sensor measured value (PV : Present Value) and when a
difference between them (E : the deviation) is detected, the controller output the
manipulate value (MV) to the actuator to eliminate the difference. The PID control consists
of three control actions that are proportional (P), integral (I), and differential (D).
The characteristics of the PID function of GM6 is as following;
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the PID function is integrated into the CPU module. Therefore, all PID control action
can be performed with F/B (Function Block) without any separated PID module.
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Forward / reverse operations are available
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P operation, PI operation, PID operation and On/Off operation can be sel ected easily.
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The manual output (the user-defined forced output) is available.
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By proper parameter setting, it can keep stable operation regardless of external
disturbance.
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The operation scan time (the interval that PID controller gets a sampling data from
actuator) is changeable for optimizing to the system characteristics.
