RefVelocity

General

Functional Description

RefVelocity represents the reference velocity, which is derived 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 taken into account (see Ref-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 derivation, 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 indicated. For this reason, the derivation causes an errant value in RefVelocity. The drive does not react to this errant value, as it no longer follows the reference values when ControllerEnable is disabled.