L_CT1P_BacklashComp

The use of this FB is recommended if high-precision positioning has to be carried out where a direction-dependent drive backlash (e.g. backlash of a gearbox or a spindle) has to be compensated.

WARNiNG!

The combination of backlash compensation with position control on an external encoder is not permitted.

Please note when using this FB:

The PLCopen status "Standstill" is entered as soon as the uncompensated setpoint specification has reached standstill. The motion FBs (e.g. MC_MoveAbsolute, MC_MoveVelocity, L_MC1P_AxisBasicControl) their status outputs (x)Busy, (x)Done etc. on the basis of the uncompensated setpoints.
If required, the xInPosition output in the MC_ReadMotionState or L_MC1P_AxisBasicControl FBs and the eContactState output of this FB can also be used for standstill detection in the application.
The compensation has an additive effect on the setpoint and is subtracted from the actual value.
The corrected setpoints are output on the FB for analysis purposes. These do not have to be connected by application.

		L_CT1P_BacklashComp
AXIS_REF	-	Axis	xBusy	-	BOOL
BOOL	-	xEnable	xActive	-	BOOL
L_MC1P_ExecutionIndex	-	eExecutionIndex	xError	-	BOOL
LREAL	-	lrBacklashWidth	eErrorID	-	L_IE1P_Error
LREAL	-	lrCompTime	lrSetPosOut	-	LREAL
L_CT1P_BacklashCompMode	-	eCompMode	lrSetVelOut	-	LREAL
			lrSetAccOut	-	LREAL
			lrSetTorqueOut	-	LREAL
			eContactState	-	L_CT1P_BacklashContactState

Name Data type	Info/adjustment options
Axis AXIS_REF	Transfer of the axis data structure Motion axes (AXIS_REF)
xEnable BOOL	FALSE -> TRUE	Activation of the FB
Activation or deactivation (TRUE <-> FALSE) can only take place when the axis is locked ("Disabled" status)
eExecutionIndex L_MC1P_ExecutionIndex	Execution index A maximum of two setpoint-correcting FBs can be connected to one axis. The call sequence is defined via this input. Selection: L_MC1P_ExecutionIndex.First := 1, L_MC1P_ExecutionIndex.Second := 2
lrBacklashWidth LREAL	Width of the backlash on the output side. Initial value: 0 For modulo axes, the value must be smaller than the cycle length of the axis Note: The value can be adapted during operation and is adopted if the compensation does not add a position correction, i.e. if one of the conditions applies: eCompMode = NegativeComp and eContactState = PositiveContact or eCompMode = PositiveComp and eContactState = NegativeContact
lrCompTime LREAL	Duration for backlash compensation in seconds Initial value: 0.1s Note: The value can be adapted during operation and is adopted if no transition trajectory is active,i.e: eContactState = PositiveContact or eContactState = NegativeContact
eCompMode L_CT1P_BacklashCompMode	Direction selection for compensation Typically, the compensation direction should be the inverse of the referencing direction. The value is accepted once with a positive xEnable edge 1: NegativeComp (initial value) The backlash is negatively compensated in the negative direction of movement There is no compensation in the positive direction 2: PositiveComp The backlash is positively compensated in the positive direction of movement There is no compensation in the negative direction

Name

Data type

Info/adjustment options

Axis

AXIS_REF

Transfer of the axis data structure

Motion axes (AXIS_REF)

xEnable

BOOL

FALSE -> TRUE

Activation of the FB

Activation or deactivation (TRUE <-> FALSE) can only take place when the axis is locked ("Disabled" status)

eExecutionIndex

L_MC1P_ExecutionIndex

Execution index

A maximum of two setpoint-correcting FBs can be connected to one axis. The call sequence is defined via this input.

Selection:

L_MC1P_ExecutionIndex.First := 1,

L_MC1P_ExecutionIndex.Second := 2

lrBacklashWidth

LREAL

Width of the backlash on the output side.

Initial value: 0

For modulo axes, the value must be smaller than the cycle length of the axis

Note:

The value can be adapted during operation and is adopted if the compensation does not add a position correction, i.e. if one of the conditions applies:

eCompMode = NegativeComp and eContactState = PositiveContact or

eCompMode = PositiveComp and eContactState = NegativeContact

lrCompTime

LREAL

Duration for backlash compensation in seconds

Initial value: 0.1s

Note:

The value can be adapted during operation and is adopted if no transition trajectory is active,i.e:

eContactState = PositiveContact or

eContactState = NegativeContact

eCompMode

L_CT1P_BacklashCompMode

Direction selection for compensation

Typically, the compensation direction should be the inverse of the referencing direction.

The value is accepted once with a positive xEnable edge

1: NegativeComp (initial value)

The backlash is negatively compensated in the negative direction of movement
There is no compensation in the positive direction

2: PositiveComp

The backlash is positively compensated in the positive direction of movement
There is no compensation in the negative direction

Name Data type	Value/meaning
xBusy BOOL	TRUE	The FB was added to the AXIS_REF setpoint path.
xActive BOOL	TRUE	The backlash compensation is active
xError BOOL	TRUE	An error has occurred. For details, see eErrorID .
eErrorID L_IE1P_Error	If xError = TRUE: Error number for the error that has occurred.
lrSetPosOut LREAL	Modified target position This output is used for analysis. It is not necessary to connect the output.
lrSetVelOut LREAL	Modified target speed This output is used for diagnostics. It is not necessary to switch the output.
lrSetAccOut LREAL	Modified target acceleration This output is used for diagnostics. It is not necessary to switch the output.
lrSetTorqueOut LREAL	Modified target torque This output is used for diagnostics. It is not necessary to switch the output.
eContactState L_CT1P_BacklashContactState	State of the backlash compensation 0: Unknown Initial state of the function block. It is not known whether/which contact is present 1: NegativeContact The backlash compensation compensates in the negative direction 2: PositiveContact The backlash compensation compensates in the positive direction 3: PositiveToNegative The backlash compensation changes from positive to negative compensation 4: NegativeToPositive The backlash compensation changes from negative to positive compensation

Name

Data type

Value/meaning

xBusy

BOOL

TRUE

The FB was added to the AXIS_REF setpoint path.

xActive

BOOL

TRUE

The backlash compensation is active

xError

BOOL

TRUE

An error has occurred. For details, see eErrorID .

eErrorID

L_IE1P_Error

If xError = TRUE: Error number for the error that has occurred.

lrSetPosOut

LREAL

Modified target position

This output is used for analysis. It is not necessary to connect the output.

lrSetVelOut

LREAL

Modified target speed

This output is used for diagnostics. It is not necessary to switch the output.

lrSetAccOut

LREAL

Modified target acceleration

This output is used for diagnostics. It is not necessary to switch the output.

lrSetTorqueOut

LREAL

Modified target torque

This output is used for diagnostics. It is not necessary to switch the output.

eContactState

L_CT1P_BacklashContactState

State of the backlash compensation

0: Unknown

Initial state of the function block. It is not known whether/which contact is present

1: NegativeContact

The backlash compensation compensates in the negative direction

2: PositiveContact

The backlash compensation compensates in the positive direction

3: PositiveToNegative

The backlash compensation changes from positive to negative compensation

4: NegativeToPositive

The backlash compensation changes from negative to positive compensation