XFC_PositionAtTime

XFC_PositionAtTime 1:

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

DcTime	Distributed clock system time. DcTime contains the lower 32 bits of the complete DcTime and covers a time range of +/- 2 seconds around the current time. In order to optimise 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	Data structure with options for position extrapolation.
Options.	SubIndex	For axes with more than one encoder the index (0..9) of the encoder to which the position refers can be specified in SubIndex.
Options.	InterpolationOptions	0: The position extrapolation is carried out with the current velocity, without taking into account the current acceleration. 1: The axis acceleration is included in the position extrapolation.
Options.	CompensationTime	additional compensation time.

Outputs

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

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

Inputs/outputs

VAR_IN_OUT
    Axis     : AXIS_REF;
END_VAR

Axis

Axis data structure

The axis data structure of type AXIS_REF addresses an axis uniquely within the system. Among other parameters it contains the current axis status, including position, velocity or error status.