Tab: Logical Axes

Axis type
Modulo	: The drive turns endlessly without limiting the traversing range (example: belt drive). Modulo settings Modulo value: Value of one cycle The value is saved in the `fPositionPeriod` parameter of the `AXIS_REF_SM3` function block. Note: If you select the Modulo drive type, then the product `fPositionPeriod` * `dwRatioTechUnitsDenom` has to be an integer.
Finite	: The drive has a fixed work area (example: one linear drive). Negative: Input field for the negative limiting value Positive: Input field for the positive limiting value

Master reference value
Set	: The set value of the master is used as the input for the logical axis and the dead-time compensation.
Actual	: The actual value of the master is used as the input for the logical axis and the dead-time compensation.

Time offset
Time offset relative to the master values	Number of cycles The set values have to be extrapolated in this time span

With the filters, it is possible to smooth the position and velocity values of an encoder using a PT1 filter.

Position

Number of cycles used as the time constant of the PT1 filter.

Value range: [0..999.9]

Value 0: No filtering is performed (raw values are returned).

The filtered return value is a combination of a PT1 filtered position signal and an additional position extrapolation using the velocity signal. The extrapolation itself also uses a PT1 filter to mitigate noise and automatically selects an appropriate time constant:

If only set values should get filtered or the axis sends the velocity signal, then the time constant of the extrapolation PT1 is the same as for the position PT1 filter.
Otherwise, an heuristic approach is used:

T_Extrapolate = (T_Pos + T_Dead) * T_Pos / T_Cycle

T_Extrapolate: Time constant from the PT1 extrapolation filter

T_Pos: Time constant from the PT1 position filter

T_Cycle: Cycle time

T_Dead: Dead time compensation, using the time shift relative to the master values of the logical axis n_Shift and the cycle time T_Cycle: T_Dead = n_Shift * T_Cycle

Velocity

Number of cycles used as the time constant of the PT1 filter.

Value range: [0..999.9]

Value 0: No filtering is performed (raw values are returned).

The filtered return value is a combination of a PT1 filtered velocity signal and an additional velocity extrapolation using the acceleration signal. Note that the extrapolation is used only if the axis sends a velocity signal or if set points should be filtered. The extrapolation itself also uses a PT1 filter to mitigate noise and automatically selects an appropriate time constant:

T_Extrapolate = (T_Vel + T_Dead) * T_Vel / T_Cycle

with

T_Extrapolate: Time constant from the PT1 extrapolation filter

T_Vel: Time constant from the PT1 velocity filter

T_Cycle: Cycle time

T_Dead: Dead time compensation, using the time shift relative to the master values of the logical axis n_Shift and the cycle time T_Cycle: T_Dead = n_Shift * T_Cycle

Velocity signal of the logical axis (fActVelocity):

Case 1: Master reference value = Set

fSetVelocity of the master axis is used as a raw value for the velocity signal of the logical axis.
Case 2: Master reference value = Actual and no velocity signal from the master axis.

The numerical derivative of the filtered position of the logical axis (fActPosition) is used as a raw value for the velocity signal of the logical axis.
Case 3: Master reference value = Actual and a velocity signal from the master axis.

The velocity signal is used as a raw value for the velocity signal of the logical axis.

Velocity filtering is performed on this raw signal. This means that if it is configured with the default value usiFilterDepthVelocity = 0, then this signal is passed unchanged to fActVelocity.

NOTICE
	In case 2, it would also be possible to use the numerical derivative of the unfiltered position (`fActPosition` of the master axis). The filtered position has been selected because in this case the `fActVelocity` of the logical axis matches the `fActPosition` in the default configuration without velocity filtering.

NOTICE
	For the velocity, the extrapolation of the filter delay is performed only in cases 1 and 3. In case 2, this would not be numerically stable or this would require too much filtering of the acceleration to be meaningful.

Acceleration of the logical axis (fActAcceleration)

Case 1: Master reference value = Set

fSetAcceleration of the master axis is used for the acceleration signal of the logical axis.
Case 2: Master reference value = Actual and a velocity signal from the master axis.

The numerical derivative of the filtered velocity of the logical axis (fActVelocity) is used for the acceleration signal of the logical axis.
Case 3: Master reference value = Actual and no velocity signal from the master axis.

The value 0 is used for the acceleration signal of the logical axis because differentiating a noisy position two times leads to unusable results.

Jerk of the logical axis (fActJerk)

The jerk of the logical axis (fActJerk) is either

Case 1: Master reference value = Set

fSetJerk of the master axis is used for the jerk signal of the logical axis.
Case 2: Master reference value = Actual

The value 0 is used for the jerk signal of the logical axis because differentiating a noisy position signal three times leads to unusable results.

IMPORTANT:

No dead time compensation is performed for the acceleration and jerk signal.

All set values (position, velocity, acceleration, and jerk) of the logical axis correspond to the actual values.

Write values	Writes the values of Input data filters and Time offset on the PLC.
Identification
ID	Unique ID of the logical axis

Online
Requirement: The PLC is in online mode.
Variable table	List of drive variables with variable name, Set value and Current value
Status	Display of the current status of the SoftMotion drive
Communication Settings	Display of the current communication status
Error	Axis error: FB error: uiDriveInterfaceError strDriveInterfaceError