FB_CTRL_PT1

Transfer function:

Step response:

VAR_INPUT

VAR_INPUT
    fIn         : FLOAT;
    fManSyncValue   : FLOAT;
    bSync       : BOOL;
    eMode       : E_CTRL_MODE;
    bHold       : BOOL;
END_VAR

fIn : Input value of the PT1 element.

fManSyncValue : Input value to which the PT1 element can be set, or that is issued at the output in manual mode.

bSync : A rising edge at this input sets the PT1 element to the value fManSyncValue.

eMode : Input that specifies the block's operating mode.

bHold : A TRUE at this input will hold the internal state (and therefore also the output) constant at its current value, independently of the input value.

VAR_OUTPUT

VAR_OUTPUT
    fOut         : FLOAT;
    eState       : E_CTRL_STATE;
    eErrorId         : E_CTRL_ERRORCODES;
    bError       : BOOL;
END_VAR

fOut : Output of the PT1 element.

eState : State of the function block.

eErrorId : Supplies the error number when the bError output is set.

bError : Becomes TRUE, as soon as an error occurs.

VAR_IN_OUT

VAR_IN_OUT
    stParams        : ST_CTRL_PT1_PARAMS;
END_VAR

stParams : Parameter structure of the PT1 element. This consists of the following elements:

TYPE
ST_CTRL_PT1_PARAMS :
STRUCT
    tCtrlCycleTime  : TIME     := T#0ms; (* controller cycle
time [TIME] *)
    tTaskCycleTime  : TIME     := T#0ms; (* task cycle time
[TIME] *)
    fKp         : FLOAT    := 0;     (* proportional gain
*)
    tT1         : TIME     := T#0ms; (* T1 *)
END_STRUCT
END_TYPE

tCtrlCycleTime : Cycle time with which the control loop is processed. This must be greater than or equal to the TaskCycleTime. The function block uses this input value to calculate internally whether the state and the output values have to be updated in the current cycle.

tTaskCycleTime : Cycle time with which the function block is called. If the function block is called in every cycle this corresponds to the task cycle time of the calling task.

fKp : Controller amplification / transfer coefficient

tT1 : Time constant

Requirements