ControllerStopJerk

General

Type	ES
Offline editable	Yes
Devices supporting the parameter	Lexium LXM52 Drive, Lexium LXM52 Linear Drive, Lexium LXM62 Drive, Lexium LXM62 Linear Drive, Lexium ILM62 Drive Module, Sercos Drive
Traceable	Yes

Functional Description

ControllerStopJerk contains the absolute value in units/s³ with which the drive is stopped. The value is effective with ControllerStop and with the drive reaction BD2 (User defined stop). The user parameter is used to define the jerk for decelerating the axis. The jerk defines how fast the acceleration is increased or decreased.

The parameter can be modified offline and online.

The default value for this parameter is 0 to add compatibility to the previous behavior of ControllerStop.

Zero (0) has a special meaning which does not correspond to the usual progress in the value range. Zero (0) means that the maximum possible jerk has been parameterized. Changing the maximum possible jerk is applied under the following conditions:

Sercos phase up
Modifying the parameter ControllerStopDec

The maximum possible jerk is defined as follows:

MaxJerk = 2 * MaxAcc [units/s²] / (CycleTime [ns] * 10^-9 [s/ns])

The minimal jerk is defined as follows:

MinJerk = 4 * MaxAcc [units/s²] / (StopTimeLim [ms] * 0.001 [s/ms])

If you specify a value exceeding MaxJerk here, ControllerStopJerk is limited to MaxJerk. If you specify a value smaller than MinJerk, ControllerStopJerk is limited to MinJerk.

The maximum and minimum values of this parameter are influenced by the object parameters UserDrivePeakCurrent, DriveStopCurrentLimit, UserMaxAcc, and StopTimeLim. If the entered value is higher than the maximum value or less than the minimum value, then the value is adjusted to a valid value. To recognize that the registered value is used, the value has to be validated after a Sercos phase up.

NOTE: Before entering ControllerStopJerk, verify the parameters MaxAcc and StopTimeLim. Changing these parameters at a later stage does not influence ControllerStopJerk. However, when reducing ControllerStopDec , the time and the necessary position range for a stop increases.

NOTICE
	MECHANICAL COLLISION OF MACHINE PARTS Set the value for ControllerStopJerk such that there is enough position range for a collision-free stop. Failure to follow these instructions can result in equipment damage.

NOTE: The parameters ControllerStopDec, ControllerStopJerk, and ControllerStopSet are supported as of V1.35.1.5 from the Sercos Drive. As of this version the Sercos Drive also implements the interface IF_ControllerStop.

User-Defined Stop

During the user-defined stop, a reference value profile, which is defined via the ControllerStopDec and ControllerStopJerk parameter, is started to stop the drive. The start values of the profile correspond with the values of the position, the speed and, if applicable, the acceleration. The profile is generated in the drive and can also be processed in case of a detected Sercos error. This function is enabled if

ControllerEnable is switched off and ControllerEnableStopMode is set to user-defined stop or
a diagnostic message is triggered with reaction BD2.

NOTE: The parameterization for devices of the type Sercos Drive is not performed automatically. A parameterization must be performed manufacturer-specific if it is supported by the respective Sercos Drive.

NOTE: The ControllerStopJerk parameter must not be modified as long as the user-defined stop is being executed.

Difference Between ControllerStop and User-Defined Stop

Compared to the user-defined stop, you can access reference values of the drive (reference position and reference acceleration) with ControllerStop; otherwise, the profile for stopping the drive is the same if the UserDefinedStopMode parameter is set to Start with reference values/ 1. By default the UserDefinedStopMode parameter is set to Start with actual values/ 0. The user-defined stop in the drive is parameterized in the PacController like the ControllerStop function using the ControllerStopDec and ControllerStopJerk parameter.

NOTE: Since the device Sercos Drive does not support the parameter StopTimeLim, the maximum value of StopTimeLim is assumed for the minimum value for the calculation formula above. This value is 10000 ms.

NOTE: The parameter value is transferred from the master to the slave via the parameter channel of the Sercos at every access. Typically, this takes about 10 ms. However, times up to 1 s may be realized if large amounts of data are transferred on the parameter channel.

The following graphic shows the dependency with other object parameters for rotary drives:

The following graphic shows the dependency with other object parameters for linear drives:

Example:

Entering J_Load has a direct impact on the parameter MaxAcc. A revision of MaxAcc only has an impact on ControllerStopDec if,

a Sercos phase up takes place or
the parameter ControllerStopDec is modified.