MC_ReadActualVelocity_BkPlcMc (from V3.0)

The function block determines the current velocity of an axis.

Inputs

VAR_INPUT
    Enable:     BOOL;
END_VAR

Name	Type	Description
Enable	BOOL	A rising edge at this input triggers an update of the velocity value.

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
    Valid:      BOOL;
    Busy:       BOOL;
    Error:      BOOL;
    ErrorID:    UDINT;
    Velocity:   LREAL;
END_VAR

Name	Type	Description
Valid	BOOL	This indicates successful determination of the velocity.
Busy	BOOL	This output is TRUE while the command is being processed.
Error	BOOL	The occurrence of an error is indicated here.
ErrorID	UDINT	An encoded indication of the cause of the error is provided here.
Velocity	LREAL	[mm/s] The actual velocity.

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 velocity is determined and reported with Valid 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.