Efficient Networks S120 manual Reference point approach for incremental measurement systems

Function modules 7.9 Basic positioner

CAUTION

During adjustment with the rotary absolute encoder, a range is aligned symmetrically around the zero point with half the encoder range within which the position is restored after switch off/on. If position tracking is deactivated (2720.0 = 0), only one encoder overflow is permitted to occur in this range (further details are given in chapter Position controller -> Actual position value conditioning). Once adjustment has been carried out, the range must not be exited because a unique reference between the actual encoder value and the mechanical components cannot be established outside the range.

If the reference point p2599 is in the encoder range, the actual position value is set in line with the reference point during adjustment. Otherwise, it is set to a corrected value in the encoder range.

No overflow occurs with linear absolute encoders, which means that the position can be restored within the entire traversing range after switch on/off once adjustment has been carried out. During adjustment, the actual position value is set in line with the reference point.

Reference point approach for incremental measurement systems

When the reference point approach (in the case of an incremental measuring system), the drive is moved to its reference point. In so doing, the drive itself controls and monitors the complete referencing cycle.

Incremental measuring systems require that after the machine has been powered-up, the absolute dimension reference is established to the machine zero point. When powering-up the position actual value x0 in the non-referenced state is set to x0 = 0. Using the reference point approach, the drive can be reproducibly moved to its reference point. The geometry with a positive starting direction (p2604 = "0") is shown in the following.

Drive Functions	261
Function Manual, (FH1), 07/2007 Edition, 6SL3097-2AB00-0BP4