Siemens SIMATIC FM 351 - Symmetrical Position of the Switch-Off and Switchover Points for Increment

8
8-18
FM 351 Positioning Function Module
EWA 4NEB 720 6001-02
In the parameterization interface you must enter the incremental dimensions
in an increment table. The list has space for a maximum of 100 increments
which are valid for the Relative incremental mode as well as for the Abso-
lute incremental mode.
Note
Note that the FM 351 does not allow any negative values for the Relative
incremental mode.
Define separate areas for relative and absolute increments in the increment
list.
You can use the setpoint value 254 as a further value for the displacement
independently of the increment table. You enter the value:
 Either in the parameterization interface for transfer from the parameter-
ization software.
 Or in the instance DB for transfer with the FC TG254.
Apart from Increment 254 another value is available with Increment 255.
You enter the value:
 Either in the parameterization interface for transfer.
 Or in the channel DB for transfer with the FC TG253_5.
You transfer the switch-off difference and the switchover difference together
with the increment. The entries from the machine data have no validity for
this increment.
In contrast to the increments 1 to 100 and 254, for Increment 255 you specify
only one value for each of the two ranges switch-off difference and switch-
over difference. These values are interpreted by the FM 351 depending on the
direction of movement as positive or negative differences.
Target
–1000 mm 1000 mm0
Switchover difference Switch-off difference
1
2
3
4
5
Working range
Target rangeStandstill range
1
2 3
4
5
Figure 8-2 Symmetrical Position of the Switch-off and Switchover Points for
Increment 255
Standard Incre-
ments 1 to 100
Increment 254
Increment 255
Switchover and
Switch-off
Difference for
Increment 255
Machine Data and Increments