FB_MTP_AnaVlv

The function block FB_MTP_AnaVlv is an object for controlling an analog valve from different sources: internal PLC logic or manual operation (e.g. via OPC UA). Switching requests and value specifications are managed independently of each other via the state machines of Operation Mode and Source Mode. The OPC UA access rights are described in the variable tables.

Controlling the valve

The specification for opening and closing the valve is made via the switching requests Open* and Close*. The state machine of the Operation Mode manages whether and from which source new switching requests are processed.

If requests are sent simultaneously to Open* and Close*, the safety position takes precedence: SafePosEn := FALSE means the valve remains in its current state. In SafePosEn = TRUE, the valve opens when SafePos = TRUE or closes when SafePos = FALSE

If Locking is active, control of the outputs via the switching requests is prevented or the safety position is assumed.

Setpoint specification

The position is specified via Pos* variables. The position specification is managed by the state machine of the Source Mode and output according to the diagram below:

Safety position

The safety position is defined via the variables SafePosEn and SafePos .

The variable SafePosEn is used to describe whether the valve has a fixed safety position (SafePosEn = TRUE) or whether the current position should be maintained (SafePosEn = FALSE)

The safety position is described with SafePos:

SafePos = FALSE: Safety position of the valve: PosMin

SafePos = TRUE: Safety position of the valve: PosMax

Additional definitions of mechanisms

Implemented interfaces

I_MTP_AnaVlv

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
StateChannel StateOffAut StateOpAut StateAutAut		See Operation Mode
OpenAut	BOOL	`Automatic` switching request to move to the selected position of the valve.	Read
CloseAut	BOOL	`Automatic` switching request to close the valve.	Read
OpenFbkCaIc	BOOL	Source of the valve-open limit switch feedback signal: 1: Calculated 0: Sensor	Read
OpenFbk	BOOL	Valve-open limit switch feedback signal	Read
CloseFbkCaIc	BOOL	Source of the feedback signal Valve-closed limit switch: 1: Calculated 0: Sensor	Read
CloseFbk	BOOL	Valve-closed limit switch feedback signal.	Read
SrcChannel SrcManAut SrcIntAut		See Source Mode
PosInt	REAL	`Internal` value specification for the position	Read
PosUnit	INT	Unit of the position	Read
PosMin	REAL	Lower limit of the value specification for the valve position	Read
PosMax	REAL	Upper limit of the value specification for the valve position	Read
PosFbkCaIc	BOOL	Source of the position feedback value: 1: Calculated 0: Sensor	Read
PosFbk	REAL	Feedback value of the position	Read
PosScIMin	REAL	Scale start of the position display	Read
PosScIMax	REAL	Scale end of the position display	Read
PermEn Permit IntlEn Interlock ProtEn Protect		See Locking
SafePosEn	BOOL	Use the safe position of the valve: 1: Use safe position. 0: Do not use safe position (Hold position).	Read
SafePos	BOOL	Safe position of the valve: 1: `PosMax` 0: `PosMin`	Read
ResetAut	BOOL	`Automatic` reset switching request: 1: Reset requested. 0: No reset requested.	Read

Outputs

Name	Type	Description	OPC UA access
StateOffAct StateOpAct StateAutAct		See Operation Mode
OpenAct	BOOL	Open valve switching command.	Read
CloseAct	BOOL	Close valve switching command.	Read
SrcManAct SrcIntAct		See Source Mode
Pos	REAL	Position setpoint on valve	Read
SafePosAct	BOOL	Safe position: 1: Move to a safe position 0: Normal operation	Read

External variables

Name	Type	Description	OPC UA access
StateOffOp StateOpOp StateAutOp		See Operation Mode
OpenOp	BOOL	`Operator` switching request to move to the selected position of the valve.	Read/write
CloseOp	BOOL	`Operator` switching request to close the valve.	Read/write
SrcManOp SrcIntOp		See Source Mode
PosMan	BOOL	`Manual` value specification for the position	Read/write
PosRbk	REAL	Unprocessed value of the `Operator` value specification for the position	Read/write
ResetOp	BOOL	`Operator` reset switching request: 0→1: `Operator` request 1→0: Request has been processed.	Read/write

Methods

Name	Type	Description
IsOffline IsOperator IsAutomatic SetOffline SetOperator SetAutomatic		See Operation Mode
IsInternal IsManual SetInternal SetManual		See Source Mode
Open	BOOL	The `Open` method allows the valve to be opened to a defined position. In this process, the `OperationMode` is transformed into the state `SetAutomatic` using the method `Automatic`. The `Aut` switching requests are set to defined values, and the internal logic is invoked. Finally, the `Aut` switching requests are reset to `False`. For position specification, the `SourceMode` is set to the `SetInternal` state using the `Internal` method. The value of the method's input variable `PosInt` is written to the input variable of the same name, `PosInt`, in this function block Returns `True` if `OpenFbk = True` and `RevFbk = False`.
Close	BOOL	The `Close` method allows the valve to be closed. In this process, the `OperationMode` is transformed into the state `SetAutomatic` using the method `Automatic`. The `Aut` switching requests are set to defined values, and the internal logic is invoked. Finally, the `Aut` switching requests are reset to `False`. For position specification, the `SourceMode` is set to the `SetInternal` state using the `Internal` method. The value of the method's input variable `PosInt` is written to the input variable of the same name, `PosInt`, in this function block Returns `True` if `OpenFbk = False` and `RevFbk = True`.