Siemens SINAMICS S120 Function Manual page 261

Note
The approach direction to the reference zero mark is, in this case, opposite to that
for axes with reference cam!
External zero mark available (p0495 0 0), no reference cam (p2607 = 0):
Synchronization to an external zero mark starts immediately after the signal at
binector input p2595 is detected (start referencing). The drive accelerates to the
velocity, specified in parameter p2608 (zero mark approach velocity) in the direc-
tion specified by the signal of binector input p2604 (reference point approach start
direction). The drive synchronizes to the first external zero mark (p0495). The drive
continues to travel with the same velocity and travel is started to the reference
point (refer to step 3).
Note
The velocity override is not effective.
An equivalent zero mark can be set using parameter p0495 (equivalent zero mark
input terminal) and the corresponding digital input selected. As standard, for
increasing actual position values, the 0/1 edge is evaluated and for decreasing
position actual values, the 1/0 edge. For the equivalent zero mark, this can be
inverted using parameter p0490 (invert measuring probe or equivalent zero mark).
Reference point approach, step 3: Travel to reference point
After the drive has successfully synchronized itself to the reference zero mark, the
travel to the reference point is started, (refer to step 2) After the reference zero
mark has been detected, the drive accelerates, flying, to the reference point
approach velocity set in parameter p2611. The axis moves through the reference
point offset (p2600) – the distance between the zero mark and the reference point.
If the axis has reached the reference point, then the position actual value and set-
point are set to the value specified using connector input p2598 (reference point
coordinate) (as standard, connector input p2598 is connected with setting parame-
ter p2599). The axis is then referenced and status signal r2684.11 is set (reference
point set).
Note
The velocity override is not effective.
If the braking distance is longer than the reference point offset or a direction
reversal is required as a result of the selected reference point offset, then after
detecting the reference zero mark, the drive initially brakes to standstill and then
travels back.
© Siemens AG 2006 All Rights Reserved
SINAMICS S120 Function Manual, 03/2006 Edition
Extended Functions
Function module "basic positioner"
4-261