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Tab: General

Table 6. Axis type and limits

Virtual mode

The drive is replaced by a simulation that is similar to a virtual drive unit. When there is a coupled drive, this does not have any effect on the fieldbus device. They function as usual without sending or receiving messages to or from a physical device.

Note: You can also set and reset a virtual mode of a drive in IEC code by means of the SMC3_ReinitDrive function block.

Modulo

_cds_icon_radiobutton_activated.png: The drive turns endlessly without limiting the traversing range (example: belt drive).

Modulo value [u]: Value of one cycle (modulo period)

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

_cds_icon_radiobutton_activated.png: The drive has a fixed work area (example: one linear drive).

Software limit switches

Activated standard icon: Position values are restricted by the lower limit Negative and an upper limit Positive.

  • Negative: Input field for the negative limiting value

  • Positive: Input field for the positive limiting value

Software error reaction

Deceleration [u/s²]:

Deceleration value when reaching the limit switch.

Max. distance [u]

Optional

The drive has to have reached a standstill within this distance after an error has occurred.

Dynamic limits: The limiting values from PLCopen Part 4 POUs are taken into consideration. Moreover, they are used by library POUs with the name SMC_ControlAxisBy* for detecting jumps.

Velocity [u/s]

Limiting value of velocity, acceleration, deceleration, and jerk

Acceleration [u/s²]

Deceleration [u/s²]

Jerk [u/s³]



Table 7. Velocity ramp type

Defines the velocity profile for motion-generating single-axis and master/slave modules:

Note: The ramp types Sin² and Quadratic (smooth) are not supported for the robotics.

Trapezoid

Trapezoidal velocity profile (with constant acceleration in each segment)

Sin²

A velocity profile as defined by the sin² function (with constant acceleration curve).

Quadratic

Acceleration profile in trapezoidal form with jerk limitation

Quadratic (smooth)

Like Quadratic but generates a jerk profile without jumps.



Table 8. Identification

ID

Integer identifier. Should be unique for each drive. For example, this identifier is used in the PLC log in order to identify the drive when an error occurs.



Table 9. Lag monitoring

Note: Lag monitoring is not available for virtual drives.

System response to a detected lag.

A lag is detected when the difference between the set position and the compensated actual position exceeds the lag limit. The extrapolated actual position is calculated in the following formula:

extrapolated actual position := actual position + actual velocity * cycle time * Axis.fSetActTimeLagCycles

This value is approximately the position that the axis will have in fSetActTimeLagCycles cycles. The value compensates the virtual lag that forms by the time displacement due to communication. The fSetActTimeLagCycles parameter is defined in the AXIS_REF_SM3 function block.

Note: When you monitor the lag, you should determine the value for fSetActTimeLagCycles and specify it in the parameters of the drive axis. For a description, see the "Determining the Dead Time of the System – Determining the Dead Time of the System" chapter.

Deactivated

No response

Lag monitoring is deactivated.

Disable drive

The bRegulatorOn bit is forced to FALSE (compare with MC_Power input) which first forces the deceleration of the drive and then the deactivation of the drive (depending on the drive implementation).

Do quickstop

The bDriveStart bit is forced to FALSE (compare with MC_Power input) which forces the drive to perform a quickstop.

Stay enabled

The drive remains switched on, but all running movements are stopped abruptly.

Lag limit:

Lag monitoring in the controller

Independent monitoring can also exist in the drive, but it is not configured in this dialog.



For more information, see: Determining the dead time of the system

Example 3. Example

The following images demonstrate the effect of the different ramp types. The position is drawn in green, the velocity in blue, and the acceleration in red.

Trapezoid

The velocity is partially linear and continuous, whereas the partially constant acceleration indicates jumps.

_sm_img_trapezoid.png

Sin²

The breaks in the velocity profile are smoothened (by using the sin² function instead of lines) to reduce the jumps in acceleration.

The user cannot limit the jerk for this ramp type. The set maximum jerk has an effect only if the acceleration does not equal zero at the beginning of the movement and the interrupted deceleration and acceleration ramp cannot be continued seamlessly. Then, taking the jerk limit into account, the acceleration is decreased to zero before the current movement is started. As compared to the trapezoidal velocity profile, the deceleration takes more time in this case.

_sm_img_sigmoidal.png

Quadratic

The acceleration is partially linear and continuous and the jerk has jumps. The velocity consists of quadratic and linear segments.

_sm_img_quadratic.png

Quadratic (smooth)

The linear acceleration ramps of the quadratic ramp type are replaced by a "smooth" function with a slope value is zero at the beginning and end. As a result, the jerk is also continuous.

Note: If a movement is interrupted, then jumps in the jerk can result.

_sm_img_quadratic_smooth.png

For more information, see: Interruption of Movements



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