RefAcceleration

General

Functional Description

RefAcceleration shows the reference acceleration, which is calculated by deduction from the reference velocity RefVelocity, in units per second². It is indicated on the drive shaft (gear box output side). The YOffsetAcceleration from the Y offset generator is not included (see Reference and Actual Values).

Coordinate displacement with SetPos (FC_SetposDual(), FC_SetposGroup(), FC_SetposSingle()) does not affect this parameter. The parameter Direction must be taken into account when interpreting RefAcceleration. The value of RefAcceleration is calculated once per Sercos cycle (CycleTime).

As ShaftRefDelay is negative and as there is a dead time due to the deduction, the following is defined:

RefAccDelay = -ShaftRefDelay - CycleTime

Relative to the reference acceleration for the drive shaft, the RefAcceleration is accelerated by the time RefAccDelay. Thus, a reference acceleration without YOffsetAcceleration is indicated for the drive shaft after the time RefAccDelay.

NOTE:  If ControllerEnable is disabled, the value of Position is cyclically copied to RefPosition. Thus, the drive is automatically synchronized to the position for the next release. RefAccel­eration is calculated from this path of positions. Disabling ControllerEnable while the drive is still in motion causes a jump in RefPosition. When calculating RefAcceleration from RefPosition, this jump is not hidden. This results in peaks with reversed signs in RefAccel­eration due to the double deduction in two sequential Sercos cycles. The drive does not react to the peaks as it no longer follows the reference values when ControllerEnable is disabled.

NOTE: The parameter value is transferred from the master to the slave via the real-time channel of the Sercos. A transmission is only possible in the Sercos phase 4 (operating phase).