Tcont_Cp; Description Tcont_Cp - Siemens SIMATIC S7-1200 Function Manual

9.4.4

TCONT_CP

9.4.4.1

Description TCONT_CP

The instruction TCONT_CP is used to control temperature processes with continuous or
pulsed control signals. The controller functionality is based on the PID control algorithm with
additional functions for temperature processes. To improve the control response with
temperature processes, the block includes a control zone and reduction of the proportional
component if there is a setpoint step change.
The instruction can set the PI/PID parameters itself using the controller optimization function.
Application
The controller controls one actuator; in other words, with one controller you can either heat
or cool but not both. If you use the block for cooling, GAIN must be assigned a negative
value. This inversion of the controller means that if the temperature rises, for example, the
manipulated variable LMN and with it the cooling action is increased.
Call
The instruction TCONT_CP must be called equidistant. To achieve this, use a cyclic interrupt
priority class (for example, OB35 for an S7-300).
The TCONT_CP instruction has an initialization routine that is run through when input
parameter COM_RST = TRUE is set. During initialization, the integral action is set to the
initialization value I_ITVAL. All the signal outputs are set to zero. Following execution of the
initialization routine, the block sets COM_RST back to FALSE. If you require initialization
when the CPU restarts, call the block in OB100 with COM_RST = TRUE.
If you call the instruction TCONT_CP as a multiple instance DB, no technology object is
created. No parameter assignment interface or commissioning interface is available. You
must assign parameters for TCONT_CP directly in the multiple instance DB and commission
it via a watch table.
See also
Operating principle of the pulse generator (Page 481)
Block diagram TCONT_CP (Page 484)
PID control
Function Manual, 03/2017, A5E35300227-AC
Instructions
9.4 PID basic functions
471