Siemens SIMATIC ET 200S - Relative Positioning (MODE 4)

1PosUniversal/Digital
7.6 Functions of the 1PosU
ET 200S Positioning
338 Operating Instructions, 05/2007, A5E00124871-04
7.6.7 Relative Positioning (MODE 4)
Definition
In relative positioning the 1PosU moves the drive from the start position in a specified
direction for a certain preset distance.
Supply the control interface with the distance to be traveled, and start MODE 4, specifying
the direction (DIR_M or DIR_P). The 1PosU moves the drive at the preset speed (SPEED
control bit) for that distance. At the switchover point the 1PosU switches from rapid feed to
creep feed, and at the switch-off it terminates the run.
If you start during an active run, the 1PosU executes the necessary change in direction after
the time T
min
has elapsed.
The preset distance is not checked by the 1PosU. This means that more than one revolution
may be involved with rotary axes.
In dosing operation relative positioning is only possible in the plus direction. The actual value
is set to 0 at every start.
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Figure 7-15 Execution of Relative Positioning