MC_ReadActualPosition_BkPlcMc (from V3.0)

The function block determines the current position of an axis.

Inputs

VAR_INPUT
    Enable:     BOOL;
END_VAR

Name	Type	Description
Enable	BOOL	Updating of the position value is initiated by a rising edge at this input.

Inputs/outputs

VAR_INOUT
    Axis:       Axis_Ref_BkPlcMc;
END_VAR

Name	Type	Description
Axis	Axis_Ref_BkPlcMc	Here, the address of a variable of type Axis_Ref_BkPlcMc should be transferred.

Outputs

VAR_OUTPUT
    Busy:       BOOL;
    Valid:      BOOL;
    Error:      BOOL;
    ErrorID:    UDINT;
    Position:   LREAL;
END_VAR

Name	Type	Description
Busy	BOOL	Indicates that a command is being processed.
Valid	BOOL	Successful determination of the actual position is indicated here.
Error	BOOL	The occurrence of an error is indicated here.
ErrorID	UDINT	An encoded indication of the cause of the error is provided here.
Position	LREAL	[mm] The actual position.

Behavior of the function block

On a rising edge at Enable the function block checks the transferred axis interface. A number of problems can be detected and reported during this process:

If the axis is in an error state and the cause is an encoder problem, the response is Error and ErrorID:=error code of the encoder.

The actual position is determined and Valid is reported if these checks can be carried out without problems.

A falling edge at Enable clears all the pending output signals.

	This function block requires no time for executing its tasks. The output Busy will never assume the value TRUE and only exists for compatibility reasons.