Mathematical formula of PID loop instruction:
M n = MP n + MI n + MD n
M n : Output value
MP n : Proportion term
MI n : Integral term
MD n : Differential term
Proportion term
MP n = K c * (SP n - PV n )
MP n : Proportion term
K c : gain
SP n : Set point
PV n : Process quantity
Integral term:
MI n = K c * T s / T I * (SP n - PV n ) + MI n-1
MI n : Integral term
K c : gain
T s : Sampling time
T I : Integral time
SP n : Set point
PV n : Process quantity
MI n-1 : Last time integral term
Differential term:
MD n = K c * T D / T s * (PV n-1 - PV n )
MD n : Differential term
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