MC_Home (Homing)

An axis reference run is carried out with the function block MC_Home.

Reference mode is set in the options with the parameter "ReferenceMode".

	The parameters involved may have to be set in the drive parameters. For the servo terminal, the parameters can be found in the objects DMC Setting (0x8030) or DMC Features (0x8031).

Inputs

VAR_INPUT
    Execute         : BOOL; 
    Position        : LREAL         := DEFAULT_HOME_POSITION;
    HomingMode      : MC_HomingMode;
    Options         : ST_HomingOptions;
END_VAR

Name	Type	Description
Execute	BOOL	The command is executed with a rising edge.
Position	LREAL	Absolute reference position to which the axis is set after homing. Alternatively, the constant DEFAULT_HOME_POSITION can be used here. In this case, the "Reference position for homing" specified in the TwinCAT System Manager is used.
HomingMode	MC_HomingMode	Determines how the calibration is performed. (Type: MC_HomingMode) MC_DefaultHoming Initiates default homing. MC_Direct Sets the axis position directly to Position without executing a movement. MC_Block Performs homing to a mechanical end stop. MC_ForceCalibration Enforces the "axis is calibrated" state. No movement takes place, and the position remains unchanged. MC_ResetCalibration Resets the calibration state of the axis. No movement takes place, and the position remains unchanged.
Options	ST_HomingOptions	Data structure containing additional parameters. SearchDirection: Direction in which the referencing cam is to be searched SearchVelocity: Velocity at which the referencing cam is to be searched SyncDirection: Direction in which the falling edge of the referencing cam is searched after the referencing cam has been detected SyncVelocity: Velocity at which the falling edge of the referencing cam is searched for after the referencing cam has been detected ReferenceMode: Referencing mode (currently only ENCODERREFERENCEMODE_CAMATDIGITALINPUT) Acceleration: Acceleration for homing Deceleration: Deceleration for homing The signal of a referencing cam must be routed to a digital terminal input (HomingMode = MC_DefaultHoming).

	Since the reference position is generally set during the motion, the axis will not stop exactly at this position. The standstill position differs by the braking distance of the axis, although the calibration is nevertheless exact.

Inputs/outputs

VAR_IN_OUT
    Axis : AXIS_REF;
END_VAR

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

Outputs

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

Name	Type	Description
Done	BOOL	TRUE when the axis has been calibrated and the movement is complete.
Busy	BOOL	TRUE as soon as the command is started with "Execute" and as long as the movement command is processed. If "Busy" is FALSE, 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	Currently not implemented - "Active" indicates that the command is running. If the command has been buffered, it may only become active after a running command has been terminated.
CommandAborted	BOOL	TRUE if the command could not be executed completely.
Error	BOOL	TRUE, if an error occurs.
ErrorID	UDINT	If the error output is set, this parameter supplies the error number.

Note

The referencing process has several phases. The following diagram illustrates the sequence after starting function block MC_Home with the individual phases for the case HomingMode = MC_DefaultHoming.

MC_Home (Homing) 7:

Requirements

Development environment	PLC libraries to include
TwinCAT 3.1.4024.11	Tc3_DriveMotionControl