MLFB_HomeFindHomeFastInput

Description

This function block performs a single-axis home to a limit switch connected to a High Speed Input. The motor starts to move according to the direction setting. The home position has been found as soon as the fast input The inputs are taken into account at each cycle depending on the system periodicity (for example each millisecond). Under certain circumstances this can be insufficient when more accuracy is needed, or if a quick response is required from the system. To fill the gap, a drive may have some Fast Input connections (generally one or two). When an event happens that triggers a Fast Input (e.g. when a sensor sends a rising edge), the detection of a signal occurs faster (which can be 1000 times more accurate than the system periodicity). Then the timestamp associated with this input can be provided to the IPC to take corrective action selected is triggered on the edge selected.

An absolute move is made to the triggered position, and then the position value is set. The hardware limit switches are monitored during the homing procedure.

The drive behaves as follows in case that a hardware limit switch is active before the home-switch has been activated: The motor changes the direction until the home switch is crossed.

The following figure shows the function block I/O:

Figure 7-239: MLFB HomeFindHomeFastInput

Arguments

Input

ibExecute	Description	Request the homing step procedure at rising edge A rising edge is the transition of a digital signal from low to high. It is also called positive edge
	Data type	BOOL
	Range	[0 , 1]
	Unit	N/A
	Default	—
iAxisID	Description	Name of a declared instance of the AXIS_REF library function
	Data type	AXIS_REF
	Range	[1 , 256]
	Unit	N/A
	Default	—
iPosition	Description	Offset Position Applied After Home Switch is found
	Data type	LREAL
	Range	—
	Unit	User unit
	Default	—
ibDirection	Description	Define the axis homing direction Value Description 0 clockwise rotation 1 counterclockwise rotation
	Data type	BOOL
	Range	[0 , 1]
	Unit	N/A
	Default	—
iVelocity	Description	Commanded velocity for the homing move
	Data type	LREAL
	Range	—
	Unit	User unit/sec
	Default	—
iAcceleration	Description	Commanded acceleration for the homing move
	Data type	LREAL
	Range	—
	Unit	User unit/sec2
	Default	—
iDeceleration	Description	Commanded deceleration for the homing move
	Data type	LREAL
	Range	—
	Unit	User unit/sec2
	Default	—
ibHomeSwitchMode	Description	Limit switch state to complete homing Value Description 0 Rising edge of switch 1 Falling edge of switch
	Data type	BOOL
	Range	[0 , 1]
	Unit	N/A
	Default	—
ibPosLimitSwitch	Description	The positive direction limit switch input I/O point
	Data type	BOOL
	Range	[0 , 1]
	Unit	N/A
	Default	—
ibNegLimitSwitch	Description	The negative direction limit switch input I/O point
	Data type	BOOL
	Range	[0 , 1]
	Unit	N/A
	Default	—
iTimeout	Description	Maximum time for homing move to complete. If exceeded the homing procedure will error out. 0= no time limit
	Data type	TIME
	Range	—
	Unit	sec
	Default	—
ibFastInputNumber	Description	Limit switch state to complete homing. Value Description 0 Fast Input The inputs are taken into account at each cycle depending on the system periodicity (for example each millisecond). Under certain circumstances this can be insufficient when more accuracy is needed, or if a quick response is required from the system. To fill the gap, a drive may have some Fast Input connections (generally one or two). When an event happens that triggers a Fast Input (e.g. when a sensor sends a rising edge), the detection of a signal occurs faster (which can be 1000 times more accurate than the system periodicity). Then the timestamp associated with this input can be provided to the IPC to take corrective action Number 1 1 Fast Input Number 2
	Data type	BOOL
	Range	[0 , 1]
	Unit	N/A
	Default	—
iCycleTime	Description	Ethercat Cycle Time 250, 500 or 1000
	Data type	LREAL
	Range	—
	Unit	microseconds
	Default	—

Output

obDone	Description	Indicates the move completed successfully. The Command Position has reached the endpoint
	Data type	BOOL
	Unit	N/A
obActive	Description	Indicates this move is the active move
	Data type	BOOL
	Unit	N/A
obError	Description	Indicates an invalid input was specified or the move was terminated due to an error
	Data type	BOOL
	Unit	N/A
oErrorID	Description	Indicates the error if Error output is set to TRUE Value Description 1 Axis in Error State 2 Axis is Not Enabled 3 Timeout Exceeded 4 SDO Read/Write Error 5 Input Parameter out of Range
	Data type	DINT
	Unit	N/A

Usage

This homing procedure performs a homing function searching for sensor A sensor is a type of transducer that converts one type of energy into another for various purposes including measurement or information transfer using only High Speed Input Switches. (A High Speed Limit Switch has 1 “Off” (or “On”) area).

• Home is commanded by user in the desired homing direction at the selected Velocity
• If LimitSwitch is found ‘On’ on rising ‘Execute’, then the process is started in the opposite direction as specified, LimitSwitch is search for ‘Off’ (or On, depending on LimitSwitchMode setting) Edge (released), and process is restarted again in original direction. This ensures that the end conditions are always the same
• The Timeout can cause an error if exceeded

Related Functions

MLFB_HomeFindHomeFastInputModulo

MLFB_HomeFindLimitFastInput

MLFB_HomeFindLimitFastInputModulo

Example

Structured Text

Direction:= 0; Position:=1000; Velocity:=1000; Acceleration:=10000; Deceleration:=10000; SwitchMode:=0; Timeout:=T#100; FastInputNumber:=0; CycleTime:=1000;   inst_fbHomeFindHomeFastInput(True, Axis1, Position, Direction, Velocity, Acceleration, Deceleration, HomeSwitchMode, PosLimitSwitch, NegLimitSwitch, Timeout, FastInputNumber, CycleTime);   HomeComplete :=inst_fbHomeFindHomeFastInput.Done; HomeActive :=inst_fbHomeFindHomeFastInput.Active; HomeError :=inst_fbHomeFindHomeFastInput.Error; HomeErrorID :=inst_fbHomeFindHomeFastInput.ErrorID;   (* PosLimitSwitch and NegLimitSwtch are declared I/O points *)

Ladder Diagram

Function Block Diagram

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