RefVelocity

General

Functional Description

RefVelocity shows the reference velocity, which is calculated by deduction from the reference position RefPosition, in units per second. It is indicated on the drive shaft (gear box output side). The YOffsetVelocity 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 RefVelocity. The value of RefVelocity 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:

RefVelDelay = -ShaftRefDelay - (CycleTime/2)

Relative to the reference velocity for the drive shaft, the RefVelocity is accelerated by the time RefVelDelay. Thus, a reference velocity without YOffsetVelocity is indicated for the drive shaft after the time RefVelDelay.

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. RefVelocity is calculated from this path of positions. Disabling ControllerEnable while the drive is still in motion causes a jump in RefPosition. When calculating RefVelocity from RefPosition, this jump is not hidden. For this reason, the deduction causes a peak in RefVelocity. The drive does not react to this peak as it no longer follows the reference values when ControllerEnable is disabled.