Drive control and features66Position reference setsThe user can define two different position reference sets. Each reference setconsists of• position reference• positioning speed reference• positioning acceleration reference• positioning deceleration reference• positioning reference filter time• positioning style• positioning speed when target is reached.One reference set is used at a time. The definition and selection of positionreference sets are done using the parameters in group 65.Dynamic position reference limiterThe dynamic limiter controls the position reference limitation in position control andsynchron control modes. Dynamic limitation of the position reference causesa synchron error (4.18 SYNC ERROR). The error is accumulated and fed back to theposition profile generator. The synchron error is corrected according to the values ofthe active positioning table parameters in group 65.Note: Make sure that parameter 65.05 < 70.04, parameter 65.06 < 70.05 andparameter 65.07 < 70.06. Otherwise, the drive may oscillate.Start/stop examples with dynamic limiterThe speed curves of the master and follower during the start and stop are presentedin the figures below.When the follower is in synchron control, the reference can be taken from theencoder or from another drive. The master can be in any control mode.Start: linear axis, relative synchronisationUsed when the master is to be distance C ahead of thefollower at start.60.02 POS AXIS MODE is set to (0) Linear. 68.07SYNCHRON MODE is set to (1) Relative.To catch the master position, the follower acceleratesup to its maximum allowed speed. Only master positionchanges which take place after the follower is startedare taken into account.Start: rollover axis60.02 POS AXIS MODE is set to (1) Rollover.The follower accelerates until it has reached the mastershaft position angle (position per one revolution,0…360 °) . Rotations of the master are not counted.tABC 70.05 POS ACCEL LIM70.06 POS DECEL LIM70.04 POS SPEED LIMMaster speedFollower speedSynchronisedSpeed A = BtSynchronpositionreferencePositionFollower positionMaster positionFollower start
