FB_HomeLimitSwitch - General Information

Overview

Type:	Function block
Available as of:	V1.0.3.0
Inherits from:	-
Implements:	-
Versions:	Current version

Task

Homing an axis to a hardware limit switch.

Description

An axis i_ifDrive is moved to the reference position. The reference position is recognized by means of the hardware limit switches that are connected to the inputs i_xHwLimitPos and i_xHwLimitNeg.

Four modes (input i_etMode) are supported for the homing:

o....PosEdge...: i_xHwLimit... = TRUE equates the condition "Sensor assigned" (normally open contact)

o....NegEdge...: i_xHwLimit... = FALSE equates the condition "Limit switch assigned" (normally closed contact)

When starting the reference travel, the following cases are distinguished:

oCase 1: The two inputs i_xHwLimitPos and i_xHwLimitNeg report the condition "Limit switch not assigned" when starting the reference travel.

oStep 1: The axis moves with the velocity i_lrVel in the defined direction until the respective input i_xHwLimitPos or i_xHwLimitNeg reports the condition "Limit switch assigned". The input i_etMode defines the direction and the desired limit switch.

oStep 2: Then the axis is moved in the opposite direction until the desired limit switch i_xHwLimitPos or i_xHwLimitNeg reports the condition "Limit switch not assigned". If thereby the hardware limit switch, in which direction the axis is moving at the time reports the condition "Limit switch moved", then an error is triggered.

oStep 3: The axis is moved in direction again that was defined by the input i_etMode, but now with the velocity i_lrLowVel until the desired limit switch i_xHwLimitPos or i_xHwLimitNeg (reference signal) reports the condition "Limit switch assigned". Afterwards the axis stops at the following position: "Position when the reference signal is given" + i_lrOffset.

oCase 2: The hardware limit switch in the axis' direction of motion (defined by the input i_etMode) is enabled.

In this case, the process is started with step 2 of case 1.

oCase 3: The two inputs i_xHwLimitPos and i_xHwLimitNeg are enabled during the start

An error is triggered.

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_etMode	ET_HomeLimitSwitchMode	Reference mode
i_lrOffset	LREAL	Offset between sensor signal and reference point. An offset is always added to the position that was held when the sensor signal occurred.
i_lrMaxTravel	LREAL	Maximum distance for referencing: The movements into the direction of motion are defined by the input i_etMode until the hardware limit switch is enabled. The maximum distance will not be considered because the following movement in the opposite direction will be allowed for the maximum defined distance. For a graphical explanation of i_lrMaxTravel.
i_lrHomePosition	LREAL	Reference position at the end of the referencing.
i_lrVel	LREAL	Velocity (change of position) in units/s.
i_lrLowVel	LREAL	Velocity (change of position) in units/s at which the edge of the hardware limit switch is to be detected.
i_lrAcc	LREAL	Acceleration (change of velocity) in units/s².
i_lrDec	LREAL	Deceleration (change of velocity) in units/s².
i_lrJerk	LREAL	Jerk (change of acceleration/deceleration) in units/s³.
i_xHwLimitNeg	BOOL	Negative hardware limit switch (digital input of the PacDrive system) Make contact (normally open).
i_xHwLimitPos	BOOL	Positive hardware limit switch input (digital input of the PacDrive system). Make contact (normally open).
i_xStart	BOOL	Starts referencing.

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_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_xMotionInstructionActive	BOOL	TRUE: The axis is processing a motion command. The output is also set if the motion command defines that the axis is at stand still, e.g. due to a standing master.
q_lrPosition	BOOL	Position of the axis.
q_xHomeOk	BOOL	Axis stops at the reference position.

Diagnostic Messages

q_etDiag	q_etDiagExt	Enumeration value	Description
OK	Disabled	9	The POU is disabled.
OK	HomingDone	222	Homing has been performed.
OK	Initializing	4	The POU is being initialized.
OK	WaitForLimitSwitchLowVel	224	Waiting for signal from LimitSwitch during travel at LowVel velocity.
OK	WaitForLimitSwitchVel	223	Waiting for signal from LimitSwitch during travel at Vel velocity.
OK	WaitForStart	5	Waiting for starting command.
OK	WaitUntilDisabled	8	Waiting until the POU is deactivated.
OK	WaitUntilLimitSwitchFree	217	Waiting until limit switch is free.
OK	WaitUntilOffsetReached	225	Waiting until the offset position has been reached.
DriveConditionInvalid	DriveNotReady	10	The drive is not ready for motion commands.
HomingFailed	SensorNotFound	220	No sensor signal was found.
InputParameterInvalid	AccRange	12	Acc is outside the valid range.
InputParameterInvalid	DecRange	13	Dec is outside the valid range.
InputParameterInvalid	DriveInvalid	3	The connected drive is invalid.
InputParameterInvalid	JerkRange	14	Jerk is outside the valid range.
InputParameterInvalid	LowVelRange	226	LowVel is outside the valid range.
InputParameterInvalid	MaxTravelRange	215	MaxTravel is outside the valid range.
InputParameterInvalid	UnknownMode	111	The Mode is indeterminable.
InputParameterInvalid	VelRange	11	Vel is outside the valid range.
LimitReached	HwLimitNegReached	219	Negative limit switch has been reached.
LimitReached	HwLimitPosReached	221	Positive limit switch has been reached.
UnexpectedProgramBehavior	UnexpectedFeedback	1	An unintended detected error occurred during execution.
UnexpectedProgramBehavior	UnknownState	2	The POU is in an undefined state.

AccRange

Enumeration name:	AccRange
Enumeration value:	12
Description:	Acc is outside the valid range.

Issue	Cause	Solution
-	At the input i_lrAcc, an invalid value has been transferred.	The following must hold: 0 < i_lrAcc < drive parameter MaxAcc For the valid value range for i_lrAcc, see output q_sMsg

Issue

Cause

Solution

At the input i_lrAcc, an invalid value has been transferred.

The following must hold: 0 < i_lrAcc < drive parameter MaxAcc

For the valid value range for i_lrAcc, see output q_sMsg

DecRange

Enumeration name:	DecRange
Enumeration value:	13
Description:	Dec is outside the valid range.

Issue	Cause	Solution
-	At the input i_lrDec, an invalid value has been transferred.	The following must hold: 0 < i_lrDec < drive parameter MaxAcc For the valid value range for i_lrDec, see output q_sMsg

Issue

Cause

Solution

At the input i_lrDec, an invalid value has been transferred.

The following must hold: 0 < i_lrDec < drive parameter MaxAcc

For the valid value range for i_lrDec, see output q_sMsg

Disabled

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

The function block is disabled and executes no actions whatsoever. i_xEnable and q_xActive are set to FALSE

DriveInvalid

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

Issue	Cause	Solution
-	At the input i_ifDrive, no drive was applied.	At the input i_ifDrive, a valid drive must be transferred.
-	The connected drive does not support all required functionalities.	Establish which functionalities are not supported by the drive by means of output q_sMsg. Use a drive which supports all required functionalities.

Issue

Cause

Solution

At the input i_ifDrive, no drive was applied.

At the input i_ifDrive, a valid drive must be transferred.

The connected drive does not support all required functionalities.

Establish which functionalities are not supported by the drive by means of output q_sMsg.

Use a drive which supports all required functionalities.

DriveNotReady

Enumeration name:	DriveNotReady
Enumeration value:	10
Description:	The drive is not ready for motion commands.

Issue	Cause	Solution
-	The axis is not in position control.	Verify the state of the axis.
-	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 axis is not in position control.

Verify the state of the axis.

The parameter State of the SERCOS bus is not 4.

Set the SERCOS bus parameter PhaseSet to 4.

Verify the SERCOS bus for errors.

HomingDone

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

The homing sequence has been completed successfully.

HwLimitNegReached

Enumeration name:	HwLimitNegReached
Enumeration value:	219
Description:	Negative limit switch has been reached.

Issue	Cause	Solution
-	While moving away from the positive limit switch, the negative limit switch was triggered.	Verify the sensors. Verify the signals at the inputs i_xHwLimitNeg and i_xHwLimitPos.
-	Both limit switches are active at the same time.	Verify the sensors. Verify the signals at the inputs i_xHwLimitNeg and i_xHwLimitPos.

Issue

Cause

Solution

While moving away from the positive limit switch, the negative limit switch was triggered.

Verify the sensors.

Verify the signals at the inputs i_xHwLimitNeg and i_xHwLimitPos.

Both limit switches are active at the same time.

Verify the sensors.

Verify the signals at the inputs i_xHwLimitNeg and i_xHwLimitPos.

HwLimitPosReached

Enumeration name:	HwLimitPosReached
Enumeration value:	221
Description:	Positive limit switch has been reached.

Issue	Cause	Solution
-	While moving away from the negative limit switch, the positive limit switch was triggered.	Verify the sensors. Verify the signals at the inputs i_xHwLimitNeg and i_xHwLimitPos.
-	Both limit switches are active at the same time.	Verify the sensors. Verify the signals at the inputs i_xHwLimitNeg and i_xHwLimitPos.

Issue

Cause

Solution

While moving away from the negative limit switch, the positive limit switch was triggered.

Verify the sensors.

Verify the signals at the inputs i_xHwLimitNeg and i_xHwLimitPos.

Both limit switches are active at the same time.

Verify the sensors.

Verify the signals at the inputs i_xHwLimitNeg and i_xHwLimitPos.

Initializing

Enumeration name:	Initializing
Enumeration value:	4
Description:	The POU is being initialized.

The function block is being initialized and thus is not yet ready to receive commands at its inputs.

The function block will signalize that it is ready for operation with the signal q_xReady = TRUE.

JerkRange

Enumeration name:	JerkRange
Enumeration value:	14
Description:	Jerk is outside the valid range.

Issue	Cause	Solution
-	At the input i_lrJerk, an invalid value has been applied.	At the input i_lrJerk, a value greater than 0 and smaller than or equal to Gc_lrMaxJerk must be transferred.

LowVelRange

Enumeration name:	LowVelRange
Enumeration value:	226
Description:	LowVel is outside the valid range.

Issue	Cause	Solution
-	At the input i_lrLowVel, an invalid value has been applied.	At the input i_lrLowVel, a value greater than 0 and smaller than the axis parameter MaxVel must be transferred.

MaxTravelRange

Enumeration name:	MaxTravelRange
Enumeration value:	215
Description:	MaxTravel is outside the valid range.

Issue	Cause	Solution
-	At the input i_lrMaxTravel, an invalid value has been applied.	At the input i_lrMaxTravel, a value greater than 0 must be transferred.

SensorNotFound

Enumeration name:	SensorNotFound
Enumeration value:	220
Description:	No sensor signal was found.

Issue	Cause	Solution
-	The sensor signal is not transmitted to the function block.	Verify the signals of the limit switch at the function block inputs i_xHwLimitNeg and i_xHwLimitPos.
-	The sensor does not transmit a signal.	Verify the power supply of the sensor. Ensure that the sensor is not covered. Ensure that the sensor can be triggered by the mechanical system. Verify the electrical connection of the sensor and the Touchprobe input.

Issue

Cause

Solution

The sensor signal is not transmitted to the function block.

Verify the signals of the limit switch at the function block inputs i_xHwLimitNeg and i_xHwLimitPos.

The sensor does not transmit a signal.

Verify the power supply of the sensor.

Ensure that the sensor is not covered.

Ensure that the sensor can be triggered by the mechanical system.

Verify the electrical connection of the sensor and the Touchprobe input.

UnexpectedFeedback

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

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

UnknownMode

Enumeration name:	UnknownMode
Enumeration value:	111
Description:	The Mode is indeterminable.

Issue	Cause	Solution
-	At the input i_etMode, an invalid value has been applied.	At the input i_etMode, an element of the enumeration ET_HomeLimitSwitchMode must be applied.

UnknownState

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

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

VelRange

Enumeration name:	VelRange
Enumeration value:	11
Description:	Vel is outside the valid range.

Issue	Cause	Solution
-	At the input i_lrVel, an invalid value has been applied.	Apply a value greater than 0 and smaller than the axis parameter MaxVel to i_lrVel.

WaitForLimitSwitchLowVel

Enumeration name:	WaitForLimitSwitchLowVel
Enumeration value:	224
Description:	Waiting for signal from LimitSwitch during travel at LowVel velocity.

The axis is moved towards the sensor at the velocity i_lrLowVel in order to obtain a more exact position.

WaitForLimitSwitchVel

Enumeration name:	WaitForLimitSwitchVel
Enumeration value:	223
Description:	Waiting for signal from LimitSwitch during travel at Vel velocity.

The axis is moved at the speed i_lrVel until it reaches the sensor.

WaitForStart

Enumeration name:	WaitForStart
Enumeration value:	5
Description:	Waiting for starting command.

The function block has completed its initialization and is waiting for a positive edge at the input i_xStart before continuing the processing.

WaitUntilDisabled

Enumeration name:	WaitUntilDisabled
Enumeration value:	8
Description:	Waiting until the POU is deactivated.

The function block is disabled. All internal states are reset and connected resources (e.g. axes) are transferred to a safe state. The function block has to be called up continuously until it reports q_xActive = FALSE.

WaitUntilLimitSwitchFree

Enumeration name:	WaitUntilLimitSwitchFree
Enumeration value:	217
Description:	Waiting until limit switch is free.

The axis is moved away from the limit switch and back into its processing range.

WaitUntilOffsetReached

Enumeration name:	WaitUntilOffsetReached
Enumeration value:	225
Description:	Waiting until the offset position has been reached.

The reference signal was detected. The axis is moved by the offset value.

Methods

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