FB_HomeAbs - General Information

Overview

Type:	Function block
Available as of:	V1.0.7.0
Inherits from:	-
Implements:	-
Versions:	Current version

Task

Write the encoder position of an axis such that a desired reference to the axis position (Axis.EncoderPosition) can be reestablished using FB_HomeSetPos in mode ET_HomeSetPosMode.RestorePosFromAxisencoder.

Description

The encoder of a servo axis is written. Afterwards the axis position (Axis.RefPosition) is set, according to the configuration of the function block. At the end, the axis position equates the value of input i_lrHomePosition, considering all the input parameters.

After the function block is switched on, the homing process is started by a positive edge at the input i_xExecute. The function block requests the disabling of the position control of the axis via the output q_xDisableDrive. Subsequently, the deactivation and the standstill of the axis are verified through the function block. After the verification the position is written to the encoder and the axis position is set, according to the input parameters.

The function block differentiates two use cases (periodic and non-periodic applications). The selection of the use case takes place via a valid value at the input i_IrUserPeriod of the function block.

Background Information for Using the FB_HomeAbs

After one-time writing the encoder value using the FB_HomeAbs function block – and so establishing a mechanical reference – later on (with FB_HomeSetPos in the mode ET_HomeSetPosMode.RestorePosFromAxisencoder) a desired reference to the axis position (Axis.RefPosition) can be reestablished from the present encoder position (Axis.EncoderPosition).

PERIODIC Applications

In this use case the EncoderPosition and the RefPosition of the axis are set within the user-defined period. After the homing, the axis position is in the interval [0; i_lrUserPeriod].

Conditions

A valid value has to be defined at the input i_lrUserPeriod. This means, the value in periodic applications must be greater zero and an integer divider of the maximum possible encoder position (encoder period).

EncoderPeriod = Axis.EncoderRange * Axis.FeedConstant * Axis.GearIn / Axis.GearOut

Information on the Value Range of i_lrHomePosition

Values that are not from the interval [0; i_lrUserPeriod] can also be defined at the input i_IrHomePosition. These values are calculated back to the interval.

Example for i_lrUserPeriod= 360 and Axis.Direction = TRUE

Function block		Object in the controller configuration
i_lrHomePosition	q_lrPosition	Axis.RefPosition	Axis.EncoderPosition
10	10	10	10
370	10	10	10
730	10	10	10
-10	350	350	350
-370	350	350	350

Information on the Direction of the Axis

The previous table describes the values that result by a right rotating motor direction (Axis.Direction= TRUE). This rotating direction is the standard setting of the axis. If the direction is changed to left (Axis.Direction= FALSE), then it must be considered, that the encoder position acts contrary to the axis position. Therefore the following changes apply for the listed table:

Example for i_lrUserPeriod= 360 and Axis.Direction = FALSE

Function block		Object in the controller configuration
i_lrHomePosition	q_lrPosition	Axis.RefPosition	Axis.EncoderPosition
10	10	10	350
370	10	10	350
730	10	10	350
-10	350	350	10
-370	350	350	10

Information on i_lrAbsEncOffset in Periodic Applications

With this use case the value at the input i_lrAbsEncOffset is ignored.

NON-PERIODIC Applications

The input parameter i_lrAbsEncOffset in non-periodic applications even allows to write/set negative values. Though the maximum possible encoder position (encoder period) is calculated:

EncoderPeriod = Axis.EncoderRange * Axis.FeedConstant * Axis.GearIn / Axis.GearOut

After the homing the value range for the axis position is in the interval [-i_lrAbsEncOffset; EncoderPeriod -i_lrAbsEncOffset].

Conditions

A valid value has to be defined at the input i_lrAbsEncOffset. This means, the value must be greater than zero. In this case the value of the input i_lrUserPeriod must be =0.

Information on the Value Range of i_lrHomePosition

Values that are not from the interval [-i_lrAbsEncOffset; EncoderPeriod -i_lrAbsEncOffset] can also be defined at the input i_IrHomePosition. These values are calculated back to the interval.

Example for:

oi_lrAbsEncOffset = 60

oAxis.EncoderRange = 10

oAxis.FeedConstant = 360

oAxis.GearIn = 1

oAxis.GearOut = 1

oAxis.Direction = TRUE

Therefore we have an encoder period of 3600 and the following interval for the axis position [-60; 3540].

Function block		Object in the controller configuration
i_lrHomePosition	q_lrPosition	Axis.RefPosition	Axis.EncoderPosition
10	10	10	10
3539	3539	3539	3539
3541	-59	-59	3541
3599	-1	-1	3599
3610	10	10	10
7210	10	10	10
-10	-10	-10	3590
-59	-59	-59	3541
-61	3539	3539	3539

Information on the Direction of the Axis

Example for:

oi_lrAbsEncOffset = 60

oAxis.EncoderRange = 10

oAxis.FeedConstant = 360

oAxis.GearIn = 1

oAxis.GearOut = 1

oAxis.Direction = FALSE

Function block		Object in the controller configuration
i_lrHomePosition	q_lrPosition	Axis.RefPosition	Axis.EncoderPosition
10	10	10	3590
3539	3539	3539	61
3541	-59	-59	59
3599	-1	-1	1
3610	10	10	3590
7210	10	10	3590
-10	-10	-10	10
-59	-59	-59	59
-61	3539	3539	61

NOTE: Exception Virtual Axis!

Using this function block only makes sense for real axes. With virtual axes the function block releases the diagnostic message q_etDiag = InputParameterInvalid in conjunction with q_etDiagExt = DriveInvalid.

NOTE: POU changes cycle time monitoring!

The POU relatively increases the settings of the cycle time monitoring in the enabled state.

The POU independently resets this relative increase when no longer required.

Hereto, the POU must be called-up correctly.

Interface

Input	Data type	Description
i_xEnable	BOOL	A rising edge FALSE -> TRUE activates the POU, a falling edge TRUE -> FALSE deactivates the POU. A deactivated POU does not execute any actions.
i_ifDrive	IF_Drive	Input for the axis that shall be controlled.
i_lrHomePosition	LREAL	Position value (Axis.RefPosition) of the axis that it shall have at the position when i_xExecute FALSE -> TRUE (calculated back to the range i_lrUserPeriod or EncoderPeriod). The position value i_lrHomePosition does not have to be within the range (0 ... EncoderPeriod or i_lrUserPeriod. However, after successful run of the POU the Axis.RefPosition is in the range i_lrUserPeriod or EncoderPeriod, see use cases above.
i_lrAbsEncOffset	LREAL	Absolute value by which the axis position can be reconstructed in the negative range in the case of non-periodic applications. For 'i_lrUserPeriod = 0' this value must be greater than 0.
i_lrUserPeriod	LREAL	Machine period > 0: periodic application: After homing the Axis.RefPosition is in the range (i_lrHomePos MOD i_lrUserPeriod); i_lrAbsEncOffset is not taken into account. = 0: not periodic application: After homing the Axis.RefPosition is in the range - i_lrAbsEncOffset ... (EncoderPeriod - i_lrAbsEncOffset)
i_xExecute	BOOL	If i_xEnable = TRUE, homing can be started via this input. If homing has been started once, it is not possible to cancel it via i_xExecute TRUE -> FALSE.

Output	Data type	Description
q_xActive	BOOL	TRUE: The POU is active and has to be executed further. FALSE: The POU is inactive.
q_xReady	BOOL	TRUE: The POU is ready to operate and can accept user commands. FALSE: The POU is not ready to accept user commands.
q_xBusy	BOOL	TRUE: Homing is active, the POU has to be executed further
q_xDone	BOOL	TRUE: Homing completed
q_etDiag	GD.ET_Diag	General library-independent statement on the diagnostic. A value not equal to ET_Diag.Ok corresponds to an diagnostic message.
q_etDiagExt	ET_DiagExt	POU-specific output on the diagnostic. q_etDiag = ET_Diag.Ok -> Status message q_etDiag <> ET_Diag.Ok -> Diagnostic message
q_sMsg	STRING[80]	Event-triggered message which gives more detailed information on the diagnostic state.
q_xDisableDrive	BOOL	TRUE: Requirement to disable position control FALSE: Requirement to enable position control
q_lrPosition	LREAL	Axis.RefPosition of the axis
q_xHomeOk	BOOL	TRUE: Axis is homed

Examples

Example with Single-Turn-Encoder (Encoder period standardized to 0 ... 360° standardized)

i_lrHomePos	i_lrAbsEncOffset	i_lrUserPeriod	Axis position according to FB_HomeAbs or FB_HomeSetPos	Run range
50	1	0	50	-1 ... 359 (Delta 360)
1000	100	0	-80	-100 ... 260 (Delta 360)
0	100	0	0	-100 ... 260 (Delta 360)
-1000	100	0	80	-100 ... 260 (Delta 360)
1000	0	360	280	0 ... 360
-1000	0	360	80	0 ... 360
1	0	36	1	0 ... 36
35	0	36	35	0 ... 36
54	0	36	18	0 ... 36
-54	0	36	18	0 ... 36
-55	0	36	17	0 ... 36

If in the example above it shall be possible to reconstruct outside the encoder period (e.g. travel range -1000 ... -640), the FB_WriteDriveEncoder POU can be used alternatively in connection with FC_ReadDriveEncoder.

Diagnostic Messages

q_etDiag	q_etDiagExt	Enumeration value	Description
OK	Disabled	9	The POU is disabled.
OK	HomingDone	222	Homing has been performed.
OK	WaitForExecute	180	Wait for execution.
OK	WaitUntilDriveDisabled	179	Waiting until the drive is deactivated.
OK	WaitUntilEncoderWritten	188	Waiting until the encoder has been written.
OK	WaitUntilPositionSetFromEncoder	263	Wait until the position has been set according to the encoder position.
OK	WritingPositionDone	184	The encoder position has been written.
ControllerConditionInvalid	SercosInterfaceInvalid	262	The G_ifSercos interface is invalid.
DriveConditionInvalid	DriveEncoderInvalid	175	The drive encoder is invalid.
DriveConditionInvalid	DriveIsMoving	182	The drive is moving.
DriveConditionInvalid	DriveNotDisabled	183	The drive is not disabled.
DriveConditionInvalid	NoAccessToEEPROM	187	The EEPROM of the drive cannot be accessed.
DriveConditionInvalid	ProgrammingInProgress	189	Writing is being performed on the encoder.
DriveConditionInvalid	ProgrammingInvalidEEPROM	186	An error has been detected while writing on the encoder EEPROM.
ExecutionAborted	AsyncInitNotFinished	290	Init has not been completed yet.
ExecutionAborted	ColdResetOfControllerNecessary	297	A cold start of the controller is required
ExecutionAborted	NoAsyncTasksCreated	289	No asynchronous task has been generated.
HomingFailed	OutsideExecutionOfControllerStopSet	325	Action has been stopped after executing ControllerStopSet.
InputParameterInvalid	AbsEncOffsetRange	178	AbsEncOffset is outside the valid range.
InputParameterInvalid	AsyncInvalid	288	The value of IF_Async is invalid.
InputParameterInvalid	DriveInvalid	3	The connected drive is invalid.
InputParameterInvalid	UserPeriodRange	177	UserPeriod is outside the valid range.
SercosConditionInvalid	SercosNotInPhaseFour	19	The Sercos bus is not in phase 4.
UnexpectedProgramBehavior	AsyncAddWasNotSuccessful	284	It was not possible to transfer an asynchronous job to a task.
UnexpectedProgramBehavior	EncoderWriteTimeOut	185	Timeout during encoder writing.
UnexpectedProgramBehavior	InterfaceCastFailed	285	The prompt for the interface was unsuccessful.
UnexpectedProgramBehavior	SemaphoreMeCreateFailed	287	The creating of a Semaphore failed
UnexpectedProgramBehavior	UnexpectedFeedback	1	An unintended detected error occurred during execution.
UnexpectedProgramBehavior	UnknownState	2	The POU is in an undefined state.

AbsEncOffsetRange

Enumeration name:	AbsEncOffsetRange
Enumeration value:	178
Description:	AbsEncOffset is outside the valid range.

Issue	Cause	Solution
-	At the input i_lrAbsEncOffset, a number <= 0 or greater than the encoder period has been transferred.	For i_lrAbsEncOffset, the following must hold: 0 < i_lrAbsEncOffset < maximum possible value of Drive.EncoderPosition. For the permissible value range for i_lrAbsEncOffset, also refer to q_sMsg output of FB_HomeAbs.

Issue

Cause

Solution

At the input i_lrAbsEncOffset, a number <= 0 or greater than the encoder period has been transferred.

For i_lrAbsEncOffset, the following must hold: 0 < i_lrAbsEncOffset < maximum possible value of Drive.EncoderPosition.

For the permissible value range for i_lrAbsEncOffset, also refer to q_sMsg output of FB_HomeAbs.

AsyncAddWasNotSuccessful

Enumeration name:	AsyncAddWasNotSuccessful
Enumeration value:	284
Description:	It was not possible to transfer an asynchronous job to a task.

Issue	Cause	Solution
-	An error has been detected and occurred in the internal execution.	Please inform the support team about this detected error.

AsyncInitNotFinished

Enumeration name:	AsyncInitNotFinished
Enumeration value:	290
Description:	Init has not been completed yet.

Issue	Cause	Solution
-	Init() method has not yet been completed.	Call up the Init() before you call up Start() for the first time. After you have called up the Init, wait until Init has been executed successfully. (Init.q_xDone = TRUE)

Issue

Cause

Solution

Init() method has not yet been completed.

Call up the Init() before you call up Start() for the first time.

After you have called up the Init, wait until Init has been executed successfully. (Init.q_xDone = TRUE)

AsyncInvalid

Enumeration name:	AsyncInvalid
Enumeration value:	288
Description:	The value of IF_Async is invalid.

Issue	Cause	Solution
-	No valid value has been transferred at the i_ifAsync input.	Verify the value at the i_ifAsync input for <> 0.

ColdResetOfControllerNecessary

Enumeration name:	ColdResetOfControllerNecessary
Enumeration value:	297
Description:	A cold start of the controller is required

Issue	Cause	Solution
-	Gc_udiNumOfAsyncTasks has been changed.	A cold start of the controller is required.

Disabled

Enumeration name:	Disabled
Enumeration value:	9
Description:	The POU is disabled.

The function block is deactivated, it executes no actions whatsoever. i_xEnable and q_xActive have the value FALSE.

DriveEncoderInvalid

Enumeration name:	DriveEncoderInvalid
Enumeration value:	175
Description:	The drive encoder is invalid.

Issue	Cause	Solution
-	The axis encoder is not supported.	Use an axis with a different encoder.

DriveInvalid

Enumeration name:	DriveInvalid
Enumeration value:	3
Description:	The connected drive is invalid.

Issue	Cause	Solution
-	No drive was applied at the i_ifDrive input.	A valid drive must be transferred to the i_ifDrive input.
-	The connected drive does not support all required functionalities.	Establish which functionalities are not supported by the drive by means of the q_sMsg output. Use a drive that supports all required functionalities.
-	The connected drive is set to virtual.	The connected drive has to be a real axis.
-	The connected drive is deactivated.	The connected drive has to be an activated axis.

DriveIsMoving

Enumeration name:	DriveIsMoving
Enumeration value:	182
Description:	The drive is moving.

Issue	Cause	Solution
-	The axis is moving.	Verify the state of the axis.

DriveNotDisabled

Enumeration name:	DriveNotDisabled
Enumeration value:	183
Description:	The drive is not disabled.

Issue	Cause	Solution
-	The axis is not in AxisState 1	Verify the state of the axis.

EncoderWriteTimeOut

Enumeration name:	EncoderWriteTimeOut
Enumeration value:	185
Description:	Timeout during encoder writing.

Issue	Cause	Solution
-	The encoder writing process has taken too long.	Verify the connection to the encoder and retry.

HomingDone

Enumeration name:	HomingDone
Enumeration value:	222
Description:	Homing has been performed.

The homing sequence has been completed successfully.

InterfaceCastFailed

Enumeration name:	InterfaceCastFailed
Enumeration value:	285
Description:	The prompt for the interface was unsuccessful.

Issue	Cause	Solution
-	An error has been detected and occurred in the internal execution.	Please inform your Schneider Electric representative about this detected error.

NoAccessToEEPROM

Enumeration name:	NoAccessToEEPROM
Enumeration value:	187
Description:	The EEPROM of the drive cannot be accessed.

Issue	Cause	Solution
-	The access to the encoder has been denied.	Verify the axis state.

NoAsyncTasksCreated

Enumeration name:	NoAsyncTasksCreated
Enumeration value:	289
Description:	No asynchronous task has been generated.

Issue	Cause	Solution
-	Gc_udiNumOfAsyncTasks = 0	Allocate Gc_udiNumOfAsyncTasks with a value > 0 and <= 10.

OutsideExecutionOfControllerStopSet

Enumeration name:	OutsideExecutionOfControllerStopSet
Enumeration value:	325
Description:	Action has been stopped after executing ControllerStopSet.

Issue	Cause	Solution
-	User has stopped active homing movement with ControllerStopSet.	Restart movement or selected a different operating mode

ProgrammingInProgress

Enumeration name:	ProgrammingInProgress
Enumeration value:	189
Description:	Writing is being performed on the encoder.

Writing is being performed on the encoder of the axis.

ProgrammingInvalidEEPROM

Enumeration name:	ProgrammingInvalidEEPROM
Enumeration value:	186
Description:	An error has been detected while writing on the encoder EEPROM.

Issue	Cause	Solution
-	Writing is already being performed on the encoder.	Please retry later.

SemaphoreMeCreateFailed

Enumeration name:	SemaphoreMeCreateFailed
Enumeration value:	287
Description:	The creating of a Semaphore failed

Issue	Cause	Solution
-	An error has been detected and occurred in the internal execution.	Please inform the support team about this detected error.

SercosInterfaceInvalid

Enumeration name:	SercosInterfaceInvalid
Enumeration value:	262
Description:	The G_ifSercos interface is invalid.

Issue	Cause	Solution
-	The global Sercos interface G_ifSercos is invalid.	Ensure that the Sercos interface G_ifSercos outside the function block is not accidentally overwritten with 0.

SercosNotInPhaseFour

Enumeration name:	SercosNotInPhaseFour
Enumeration value:	19
Description:	The Sercos bus is not in phase 4.

Issue	Cause	Solution
-	The parameter State of the SERCOS bus is not 4.	Set the SERCOS bus parameter PhaseSet to 4. Verify the SERCOS bus for errors.

Issue

Cause

Solution

The parameter State of the SERCOS bus is not 4.

Set the SERCOS bus parameter PhaseSet to 4.

Verify the SERCOS bus for errors.

UnexpectedFeedback

Enumeration name:	UnexpectedFeedback
Enumeration value:	1
Description:	An unintended detected error occurred during execution.

Issue	Cause	Solution
-	An internal execution error has been detected.	Please inform your Schneider Electric representative about this detected error.

UnknownState

Enumeration name:	UnknownState
Enumeration value:	2
Description:	The POU is in an undefined state.

Issue	Cause	Solution
-	An internal execution error has been detected.	Please inform your Schneider Electric representative about this detected error.

UserPeriodRange

Enumeration name:	UserPeriodRange
Enumeration value:	177
Description:	UserPeriod is outside the valid range.

Issue

Cause

Solution

The input i_lrUserPeriod is negative.

For the input i_lrUserPeriod, a positive value or zero must be specified.

The i_lrUserPeriod input does not fit into the encoder period.

The input i_lrUserPeriod must be chosen such that the following formula is fulfilled:

ABS(lrEncoderPeriode/i_lrUserPeriod - TRUNC_INT(lrEncoderPeriode / i_lrUserPeriod)) = 0

with

lrEncoderPeriode := EncoderRange * FeedConstant * DINT_TO_LREAL(GearIn) / DINT_TO_LREAL(GearOut)

EncoderRange, FeedConstant, GearIn and GearOut are parameters of the i_ifDrive axis.

WaitForExecute

Enumeration name:	WaitForExecute
Enumeration value:	180
Description:	Wait for execution.

The function block is ready. As reaction to a positive edge from i_xExecute, the data is written in the encoder and the axis position is set accordingly.

WaitUntilDriveDisabled

Enumeration name:	WaitUntilDriveDisabled
Enumeration value:	179
Description:	Waiting until the drive is deactivated.

The function block awaits the disabling of the axis.

WaitUntilEncoderWritten

Enumeration name:	WaitUntilEncoderWritten
Enumeration value:	188
Description:	Waiting until the encoder has been written.

Writing is being performed on the encoder of the axis.

WaitUntilPositionSetFromEncoder

Enumeration name:	WaitUntilPositionSetFromEncoder
Enumeration value:	263
Description:	Wait until the position has been set according to the encoder position.

The function block awaits the setting of the axis according to the encoder position.

WritingPositionDone

Enumeration name:	WritingPositionDone
Enumeration value:	184
Description:	The encoder position has been written.

Writing on the axis encoder has been completed.

Methods

Name	Description
RegisterLoggerPoint	Registering the logger points of the POU in the Application Logger