Using Pid_Temp; Technology Object Pid_Temp - Siemens SIMATIC S7-1200 Function Manual

Using PID_Temp

6.1

Technology object PID_Temp

The PID_Temp technology object provides a continuous PID controller with integrated
tuning. PID_Temp is especially designed for temperature control and is suited for heating or
heating/cooling applications. Two outputs are available for this purpose, one each for heating
and cooling. PID_Temp can also be used for other control tasks. PID_Temp is cascadable
and can be used in manual or automatic mode.
PID_Temp continuously acquires the measured process value within a control loop and
compares it with the set setpoint. From the resulting control deviations, the instruction
PID_Temp calculates the output value for heating and/or cooling which is used to adjust the
process value to the setpoint. The output values for the PID controller consist of three
actions:
● Proportional action
The proportional action of the output value increases in proportion to the control
deviation.
● Integral action
The integral action of the output value increases until the control deviation has been
balanced.
● Derivative action
The derivative action increases with the rate of change of control deviation. The process
value is corrected to the setpoint as quickly as possible. The derivative action will be
reduced again if the rate of change of control deviation drops.
The instruction PID_Temp calculates the proportional, integral and derivative parameters for
your controlled system during "pretuning". "Fine tuning" can be used to tune the parameters
further. You do not need to manually determine the parameters.
Either a fixed cooling factor or two PID parameter sets can be used for heating-and-cooling
applications.
Additional information
● Overview of software controller (Page 38)
● Add technology objects (Page 40)
● Configure technology objects (Page 42)
● Configuring PID_Temp (Page 158)
PID control
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