Table of Contents

Three-point P controller

Block name

T8_THREE_POINT_CONTROLLER

ST call

PROGRAM TEST_T8
    VAR 
        REAL1,REAL2,REAL3,REAL4,REAL5,REAL6: REAL;
      TIME1,TIME2,TIME3,TIME4,TIME5,TIME6   :TIME;
        BOOL1,BOOL2,BOOL3,BOOL4,BOOL5,BOOL6:BOOL;
       FB: LIB.HVAC.V1_0.T8_THREE_POINT_CONTROLLER;
    END_VAR
 FB(X:= REAL1, W:= REAL2, BCRASH:= BOOL1, BR:= BOOL2, ENABLED:= BOOL3, BSP:= BOOL4, TOLMIN:= REAL3, TOLMAX:= REAL4, TROPEN:= TIME1, TRCLOSE:= TIME2, T0:= TIME3, TIMPMIN:= TIME4, TIMPMAX:= TIME5, CLOSE=>BOOL5, OPEN=>BOOL6, OUT=>REAL5, TIMEPERIOD=>TIME6);
END_PROGRAM

Library

LIB\HVAC

Version

V1.0

Description

The block is a P-controller with a three-point output.

Inputs

Input Typ Description Default value
X REALReal (measured) value 0
W REALSetpoint value 0
BCRASH BOOLSignal for fast travel to a safe position, when activated, the safe position output is active permanently False
BR BOOLReset (sync) input to travel to a safe position and reset the internal position counter False
ENABLEDBOOLSynchronisation enabled False
T0 TIMELength of gap (pause) between the pulses 4s
TIMPMAXTIMEMax. length of output pulse 2,5s
TIMPMINTIMEMin. length of output puls 1,5s
TOLMAX realUpper tolerance limit

*
X-W>TOLMAX – the control pulse length is TIMPMAX,
* TOLMIN
X-WTOLMAX – the control pulse length changes between TIMPMIN and TIMPMAX.2
TOLMIN REALLower tolerance limit - at X-W<TOLMIN the outputs are inactive 1
TRCLOSETIMETravel time 100 % to 0 % 65s
TROPEN TIMETravel time 0 % to 100 % 65s

Outputs

Output Typ Description
CLOSE BOOLCommand to open
OPEN BOOLCommand to close
OUT REALExpected (calculated) position (0%…100%)
TIMEPERIODTIMEAuxiliary value - calculated length of the control pulse period

Function

The block is used where a 3-point actuator has to be controlled using a P algorithm. The output pulse length is proportional to the difference between real and setpoint values. Parameters T0, TIMPMAX, and TIMPMIN are set instead of the bandwidth or gain.


Application example

Similar to T2, however, the P controller is part of the three-point control block, and not a separate function block.