Loop Traverse - Siemens SIMATIC FM 351 Manual

9.7

Loop Traverse

Definition
With "loop traverse", you specify the direction in which a target will be approached
with force contact. You can use the loop traverse when force contact between the
motor and the axis can only be ensured in one direction.
A target which is approached against the specified direction is first overshot. The
FM 351 then reverses the direction and approaches the target in the specified
direction.
Requirements
You have set the parameters for the axis.
The axis must be synchronized.
In a loop traverse in a direction opposite to the direction to the target, the
maximum target position is as follows:
– in the plus travel direction
target
switchover difference minus
– in the minus travel direction
target
switchover difference plus
A loop traverse is not executed if the target is approached in the direction of
the loop traverse. In this case, an incremental approach without direction
reversal is executed.
The sequence of the "incremental approach" mode must be familiar (see
Section 9.4, page 9-17).
Sequence of Loop Traverse
1. Set the control signal for the "absolute/relative incremental approach" mode
(MODE_IN=4/5).
2. Set the control signal for drive enable (DRV_EN=1).
3. Set the function switch for "do not evaluate enable input"
(EI_OFF=1) or wire up the enable input for the relevant channel.
4. Enter the incremental dimension number (MODE_TYPE=1...100, 254, 255).
5. Set the function switch (PLOOP_ON / MLOOP_ON=1).
6. Start the incremental approach
FM 351 Positioning Module
C79000-G7076-C351-02
1
SLE – / target range – switch-off difference plus –
2
1
SLS + / target range + switch-off difference minus +
2
Modes and Jobs
9-27