XFC_StepReferencePulseDetection

This function block performs the search for a zero pulse of an encoder.

A zero pulse is not present in all encoders and occurs only once per encoder revolution. The advantage of using a zero pulse for referencing is the high accuracy of this signal compared to that of a standard sensor.

The "…Detection" version of this function block does not manipulate the current position of the axis at the end of the sequence, but instead returns the detected position to the user as "RecordedPosition".

Inputs

VAR_INPUT
    Execute         : BOOL;
    Direction       : MC_Home_Direction;
    SwitchMode      : MC_Switch_Mode;
    ReferenceSignal : XFC_Ref_Signal_Ref;
    Velocity        : LREAL;
    Acceleration    : LREAL;
    Deceleration    : LREAL;
    Jerk            : LREAL;
    TimeLimit       : TIME;
    DistanceLimit   : LREAL;
    TorqueLimit     : LREAL;
    BufferMode      : MC_BufferMode;
    Options         : ST_Home_Options4;
END_VAR

Name	Type	Description
Execute	BOOL	The command is executed with a rising edge at the Execute input.
Direction	MC_Home_Direction	Enumeration that defines the initial direction of movement for the search procedure.
SwitchMode	MC_Switch_Mode	Enumeration that defines the final condition for the search procedure.
ReferenceSignal	XFC_Ref_Signal_Ref	This structure defines the source of the reference cam signal.
Velocity	LREAL	Maximum travel velocity (>0).
Acceleration	LREAL	Acceleration (≥0). If the value is 0, the standard acceleration from the axis configuration in the System Manager is used.
Deceleration	LREAL	Deceleration (≥0). If the value is 0, the standard deceleration from the axis configuration in the System Manager is used.
Jerk	LREAL	Jerk (≥0). If the value is 0, the standard jerk from the axis configuration in the System Manager is used.
TimeLimit	TIME	Exceeding this time leads to the search procedure being aborted.
DistanceLimit	LREAL	Exceeding this distance in relation to the start position leads to the search procedure being aborted.
TorqueLimit	LREAL	The motor torque is limited to this value in order to avoid mechanical damage.
BufferMode	MC_BufferMode	Currently not implemented.
Options	ST_Home_Options4	DisableDriveAccess: Set to FALSE for Beckhoff drives, usually to TRUE for third-party drives (see info). EnableLagErrorDetection: In the step functions, the lag error detection is switched off in order to ensure a smooth referencing process. If it would be purposeful to keep the lag error detection active in an application, this can be achieved by setting this flag.

	If DisableDriveAccess = TRUE, the user is responsible for modifying and reconstructing required drive parameters. The parameters required for the intended homing sequence must be agreed with the manufacturer of the third-party drive.

/ Inputs/Outputs

VAR_IN_OUT
    Axis      : AXIS_REF;
    Parameter : MC_HomingParameter;
END_VAR

Name	Type	Description
Axis	AXIS_REF	Axis data structure of the type AXIS_REF, which uniquely addresses an axis in the system. Among other parameters it contains the current axis status, including position, velocity or error state.
Parameter	MC_HomingParameter	Data structure of the type MC_HomingParameter, which must be transferred from function block to function block over the entire homing sequence.

Outputs

VAR_OUTPUT
    Done             : BOOL;
    Busy             : BOOL;
    Active           : BOOL;
    CommandAborted   : BOOL;
    Error            : BOOL;
    ErrorID          : UDINT;
    RecordedPosition : LREAL;
END_VAR

Name	Type	Description
Done	BOOL	Becomes TRUE, if the command was completed successfully.
Busy	BOOL	The Busy output becomes TRUE when the command is started with Execute and remains TRUE as long as the command is processed. When Busy becomes FALSE again, the function block is ready for a new order. At the same time one of the outputs, Done, CommandAborted or Error, is set.
Active	BOOL	Indicates that the command is executed.
CommandAborted	BOOL	Becomes TRUE, if the command could not be fully executed.
Error	BOOL	Becomes TRUE, as soon as an error occurs.
ErrorID	UDINT	If the error output is set, this parameter supplies the error number.
RecordedPosition	LREAL	Axis position at which the event was recorded.