XFC_PositionAtTime

The function block XFC_PositionAtTime calculates an axis position, which will be or was valid at a given time.

The function extrapolates the position in relation to the current position and dynamics. Precise extrapolation is only possible over a short interval, since the axis dynamics may change.

The function block requires precisely one call in order to provide the result. It can therefore be used similar to a function, although as well as the position it may also return an error. This error must be analyzed in order to ensure that the calculated position is valid.

Inputs

VAR_INPUT
    DcTime  : T_DCTIME32; 
    Options : ST_NcTimeConversionOptions;
END_VAR

Name	Type	Description
DcTime	T_DCTIME32	Distributed Clock System Time. Contains the lower 32 bits of the complete DcTime, thus covering a time range of +/- 2 seconds around the current time. In order to optimize the calculation of the position value, the time should be close to the current time, i.e. only a few PLC or NC cycles in the future or the past.
Options	ST_NcTimeConversionOptions	Data structure with options for position extrapolation.

Name

Type

Description

DcTime

T_DCTIME32

Distributed Clock System Time.

Contains the lower 32 bits of the complete DcTime, thus covering a time range of +/- 2 seconds around the current time. In order to optimize the calculation of the position value, the time should be close to the current time, i.e. only a few PLC or NC cycles in the future or the past.

Options

ST_NcTimeConversionOptions

Data structure with options for position extrapolation.

/ Inputs/Outputs

VAR_IN_OUT
    Axis     : AXIS_REF;
END_VAR

Name	Type	Description
Axis	AXIS_REF	The axis data structure of type AXIS_REF addresses an axis unambiguously within the system. Among other parameters, it contains the current axis status, including position, velocity or error state.

Outputs

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

Name	Type	Description
Position	LREAL	Extrapolated position that will be or was reached at the specified time DcTime.
Error	BOOL	Becomes TRUE if an error occurs.
ErrorID	UDINT	If the error output is set, this parameter supplies the error number.