Siemens Sinamics S110 Function Manual page 247

Search for reference, step 1: travel to reference cam
If there is no reference cam present (p2607 = 0), go to step 2.
When the referencing process is started, the drive accelerates at maximum acceleration
(p2572) to the reference cam approach velocity (p2605). The direction of the approach is
determined by the signal of binector input p2604 (search for reference start direction).
When the reference cam is reached, this is communicated to the drive using the signal at
binector input p2612 (reference cam); the drive then brakes down to standstill with the
maximum deceleration (p2573).
If a signal at binector input p2613 (reversing cam, MINUS) or at binector input p2614
(reversing cam, PLUS) is detected during reference point approach, the search direction is
reversed.
If the minus reversing cam is approached in the positive direction of travel or the plus
reversing cam in the negative direction of travel, fault message F07499 "EPOS: Reversing
cam approached from the wrong direction" is generated. In this case, the reversing cam
connections must be checked (BI: p2613, BI: p2614) or the direction of approach to the
reversing cam.
The reversing cams are low active. If both reversing cams are active (p2613 = "0" and p2614
= "0"), the drive remains stationary. As soon as the reference cam is found, then
synchronization to the reference zero mark is immediately started (refer to step 2).
If the axis leaves its start position and travels the distance defined in parameter p2606 (max.
distance to reference cam) heading towards the reference cam without actually reaching the
reference cam, the drive remains stationary and fault F07458 (reference cam not found) is
issued.
If the axis is already located at the cam, when referencing is started, then traversing to the
reference cam is not executed, but synchronization to the reference zero mark is
immediately started (refer to step 2).
Note
The velocity override is effective during the search for the cam. By changing the encoder
data set, status signal r2684.11 (reference point set) is reset.
The cam switch must be able to delivery both a rising and a falling edge. For a reference
point approach with evaluation of the encoder zero mark, for increasing position actual
values the 0/1 edge is evaluated and for decreasing position actual values, the 1/0 edge.
Inversion of the edge evaluation is not possible at the sensor zero mark.
If the length measuring system has several zero marks which repeat at cyclic intervals (e.g.
incremental, rotary measuring system), you must ensure that the cam is adjusted so that the
same zero mark is always evaluated.
The following factors may impact the behavior of the "reference cam" control signal:
 Switching accuracy and time delay of reference cam switch
 Position controller cycle of drive
 Interpolation cycle of drive
 Temperature sensitivity of machine's mechanical system
Function Manual
Function Manual, 01/2011, 6SL3097-4AB10-0BP3
Drive functions
7.3 Function modules
245