MechRefVelocity

General

Functional Description

MechRefVelocity represents the reference velocity, which is derived from the reference position MechRefPosition, in units per second. It is indicated on the drive shaft (gear box output side). The YOffsetVelocity from the Y offset generator is 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 MechRefVelocity. The value of MechRefVelocity 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 MechRefVelocity is accelerated by the time RefVelDelay. Thus, a reference velocity including YOffsetVelocity is indicated for the drive shaft after the time RefVelDelay.

NOTE:  If ControllerEnable is disabled, the value of MechPosition is cyclically copied to MechRefPosition. Thus, the drive is automatically synchronized to the position for the next release. MechRefVelocity is calculated from this path of positions. If ControllerEnable is switched off while the drive is still in motion, then a jump occurs in the MechRefPosition. When calculating MechRefVelocity from MechRefPosition, this jump is indicated. For this reason, the derivation causes an errant value in MechRefVelocity. The drive does not react to this errant value as it no longer follows the reference values when ControllerEnable is disabled.