FB_MTP_PIDCtrlBase

The function block FB_MTP_PIDCtrlBase serves as an interface for using a PID controller from different sources: internal PLC logic or manual operation (e. g. via OPC UA). Value specifications are managed independently of each other by the state machines of Operation Mode and Source Mode. The OPC UA access rights are described in the variable tables.

	The `FB_MTP_PIDCtrlBase` is an abstract function block. This cannot be instantiated, but must be derived (see syntax)!

State machines

The source of the setpoint SP* is managed via the state machine of the Source Mode. The source of the output manipulated variable MV* is managed via the state machine of the Operation Mode: Output value of the PID logic or specification by manual operation MVMan.

PID controller

The PID logic (PIDLogic()) can be freely selected. The PID logic is called via the method PIDLogic(). The parameters for the controller are described via the inputs P, Ti and Td. The output MV describes the current manipulated variable depending on the current states of the state machines. The output SP shows the currently used setpoint of the PID logic.

The function block works according to the following scheme:

Further characteristics

Syntax

FUNCTION_BLOCK FB_MTP_PIDCtrl EXTENDS FB_MTP_PIDCtrlBase
VAR
    ///Controller Toolbox (delete if you want to use own PID Logic)
    CTRL_PID: FB_CTRL_PID;
    PIDParams: ST_Ctrl_PID_PARAMS;
END_VAR

SUPER^();

Inputs

Name	Type	Description	OPC UA access
TagName	STRING	Name of the interface	-
TagDescription	STRING	Description of the interface	-
WQC	BYTE	Worst Quality Code	Read
OSLevel	BYTE	Level must be defined for system. Value 0 is reserved for local operation.	Read/write
State*		See Operation Mode
MVUnit	INT	Unit of manipulated variable	Read
MVSclMin	REAL	Minimum value of the manipulated variable display	Read
MVSclMax	REAL	Maximum value of the manipulated variable display	Read
MVMin	REAL	Minimum value of the manipulated variable	Read
MVMax	REAL	Maximum value of the manipulated variable	Read
Src*		See Source Mode
SPInt	REAL	`internal` setpoint specification	Read
SPUnit	INT	Unit of the setpoint	Read
SPIntMin	REAL	Lower limit value of the `internal` setpoint specification	Read
SPIntMax	REAL	Upper limit value of the PEA internal setpoint specification	Read
SPManMin	REAL	Lower limit value of the manual setpoint specification	Read
SPManMax	REAL	Upper limit value of the manual setpoint specification	Read
SPSclMin	REAL	Minimum value for the display of the setpoint specification	Read
SPSclMax	REAL	Maximum value for the display of the setpoint specification	Read
PV	REAL	Process value	Read
PVUnit	INT	Unit of the process value	Read
PVSclMin	REAL	Minimum value for displaying the process value	Read
PVSclMax	REAL	Maximum value for displaying the process value	Read
P	REAL	Proportional gain of the controller	Read
Ti	REAL	Integral action time of the controller [s]	Read
Td	REAL	Derivative action time of the controller [s]	Read

Outputs

Name	Type	Description
State*		See Operation Mode
MV	REAL	Current manipulated variable of the controller
Src*		See Source Mode
SP	REAL	Setpoint currently used by the controller.

External variables

Name	Type	Description	OPC UA access
State*		See Operation Mode
MVMan	REAL	`Manual` specification of the manipulated variable	Read/write
Src*		See Source Mode
SPMan	REAL	`Manual` setpoint specification	Read/write

Methods

Name	Description
PIDLogic	Implementation of the logic for calling the PID controller
ResetPID	Resetting the PID controller

Further Information