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MCFB_StepRefPulse

Description

This function block performs homing by searching for Zero pulseOutput once per turn from incremental encoders, used to zero the machine (also called Marker or reference pulse) in encoder. The reference pulse appears once per encoder revolution. The advantage in using Reference PulseWhen the step gets activated, the action is activated for a single execution, and possibly once again when the step is deactivated for homing is the higher accuracy and precision that can be achieved compared to traditional optical, mechanical or magnetic sensors.

The following figure shows the function block I/O:

MCFB StepRefPulse

Figure 11-212: MCFB StepRefPulse

Arguments

Input

Execute

Description

Request the homing step procedure at rising edgeA 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

—

AxisID

Description

Name of a declared instance of the AXIS_REF library function

Data type

AXIS_REF

Range

[1 , 256]

Unit

n/a

Default

—

Direction

Description

Define the axis homing direction

Value	Description
0	clockwise rotation
1	counterclockwise rotation

Data type

BOOL

Range

[0 , 1]

Unit

n/a

Default

—

SwitchMode

Description

Switch state to complete homing

Value	Description
0	switch is on
1	switch if off
2	rising edge of switch
3	falling edge of switch

Data type

DINT

Range

[0 , 3]

Unit

n/a

Default

—

Velocity

Description

Commanded velocity for the homing move

Data type

LREAL

Range

—

Unit

User unit/sec

Default

—

Acceleration

Description

Commanded acceleration for the homing move

Data type

LREAL

Range

—

Unit

User unit/sec²

Default

—

Deceleration

Description

Commanded deceleration for the homing move

Data type

LREAL

Range

—

Unit

User unit/sec²

Default

—

JerkIn physics, jerk is the rate of change of acceleration; more precisely, the derivative of acceleration with respect to time

Description

Commanded jerkIn physics, jerk is the rate of change of acceleration; more precisely, the derivative of acceleration with respect to time for the homing move (if zero, then trapezoidal acc/dec is used)

Data type

LREAL

Range

—

Unit

User unit/sec³

Default

—

SetPosition

Description

Value of the absolute position to be set when the homing move is done

Data type

LREAL

Range

—

Unit

User unit

Default

—

TorqueLimit

Description

Maximum torqueTorque is the tendency of a force to rotate an object about an axis. Just as a force is a push or a pull, a torque can be thought of as a twist applied for the homing move

Data type

LREAL

Range

—

Unit

User unit

Default

—

TimeLimit

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

—

DistanceLimit

Description

Maximum distance for homing move to complete. If exceeded the homing procedure will error out. 0= no distance limit

Data type

LREAL

Range

—

Unit

User unit

Default

—

BufferMode

Description

Define the homing move start action

Value	Description
0	abort
1	buffer
2	Blend to active
3	blend to next
4	blend to low velocity
5	blend to high velocity

See table in Buffer Modes

Data type

SINT

Range

[0 , 5]

Unit

n/a

Default

—

Output

Done

Description

Indicates the move completed successfully.

The Command Position has reached the endpoint

Data type

BOOL

Unit

n/a

Busy

Description

High from the moment the Execute input is one-shot to the time the move is ended

Data type

BOOL

Unit

n/a

Active

Description

Indicates this move is the active move

Data type

BOOL

Unit

n/a

CommandAborted

Description

Indicates the move was aborted

Data type

BOOL

Unit

n/a

Error

Description

Indicates an invalid input was specified or the move was terminated due to an error

Data type

BOOL

Unit

n/a

ErrorID

Description

Indicates the error if Error output is set to TRUE

Value	Description
1	TimeLimit exceeded
2	DistanceLimit exceeded
3	TorqueLimit exceeded
4	axis error stop state
5	axis not enabled
6	invalid inputs for Velocity-Acceleration-Deceleration

Data type

INT

Unit

n/a

Usage

This function Block performs homing by searching for Zero pulse (also called Marker or reference pulse) in encoder. The reference pulse appears once per encoder revolution.

Home is commanded by user in the desired homing direction at the programmed velocity.
First occurrence of the Reference Pulse, HomingThe Homing procedure allows, based on a position measurement, to set a position offset to the motor in order to ensure it is physically at the home position is finished
TorqueTorque is the tendency of a force to rotate an object about an axis. Just as a force is a push or a pull, a torque can be thought of as a twist is limited. Time and Distance Limits can cause error if exceeded
This FunctionA function calculates a result according to the current value of its inputs. A function has no internal data and is not linked to declared instances. modifies actual position and sets to the “SetPosition” input value at the end

It is common that a first approach is performed against a mechanical sensorA sensor is a type of transducer that converts one type of energy into another for various purposes including measurement or information transfer at higher velocity, and after a Reference Pulse, at a lower velocity. This is a traditional 2-Step homing (Coarse by external Switch in reverse and Fine by Reference Pulse in forward).