Pid_3Step Instruction - Siemens SIMATIC S7 System Manual
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9.2.3
PID_3STEP instruction
The PID controller uses the following formula to calculate the output value for the PID_3Step
instruction.
Δ y = K
y
w
K
p
T
1
T
D
Table 9- 15
PID_3Step instruction
LAD / FBD
STEP 7 automatically creates the technological object and instance DB when you insert the instruction. The instance
1
DB contains the parameters of the technological object.
In the SCL example, "PID_3Step_1" is the name of the instance DB.
2
S7-1200 Programmable controller
System Manual, 11/2011, A5E02486680-05
[
· s ·
(b · w - x) +
p
T
Output value
Setpoint value
Proportional gain
(P component)
Integral action time
(I component)
Derivative action time
(D component)
SCL
"PID_3Step_1"(
SetpoInt:=_real_in_,
Input:=_real_in_,
ManualValue:=_real_in_,
Feedback:=_real_in_,
InputPer:=_word_in_,
FeedbackPer:=_word_in_,
ManualEnable:=_bool_in_,
ManualUP:=_bool_in_,
ManualDN:=_bool_in_,
ActuatorH:=_bool_in_,
ActuatorL:=_bool_in_,
Reset:=_bool_in_,
ScaledInput=>_real_out_,
ScaledFeedback=>_real_out_,
ErrorBits=>_dword_out_,
OutputPer=>_word_out_,
State=>_int_out_,
OutputUP=>_bool_out_,
OutputDN=>_bool_out_,
SetpoIntLimitH=>_bool_out_,
SetpoIntLimitL=>_bool_out_,
InputWarningH=>_bool_out_,
InputWarningL=>_bool_out_,
Error=>_bool_out_);
1
T
· s
D
(w - x) +
· s
a · T
· s + 1
I
D
x
s
a
b
c
102BTechnology instructions
]
(c · w - x)
Process value
Laplace operator
Derivative delay coefficient
(D component)
Proportional action weighting
(P component)
Derivative action weighting
(D component)
Description
PID_3Step configures a PID controller with
self-tuning capabilities that has been
optimized for motor-controlled valves and
actuators. It provides two Boolean outputs.
PID_3Step is a PIDT1controller with anti-
windup and weighting of the P- and D-
components.
9.2 PID control
331
- Quick Links:
- Introducing the S7-1200 Plc
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