Siemens SIMATIC FM 351 - Page 101

Modes and Jobs
9-15
FM 351 Positioning Module
C79000-G7076-C351-02
Reference Point Approach Depending on the Start Position
The actual situation in a reference point approach depends on the following:
• the position of the drive at the start of a reference point approach
• the selected start direction
• the set position of the zero marker for the reference point switch.
Table 9-3 explains all the situations for REFPT_TYPE 0 and 1. The diagrams apply
analogously to REFPT_TYPE 2 and 3.
Table 9-3 Options for a Reference Point Approach
Conditions for a Reference Point Approach
Sequence of a Reference Point Approach
Example of a reference point approach
(REFPT_TYPE=0):
• Start direction is plus.
• Position of the zero marker from the reference
point switch is set in the plus direction.
vrapid
v
creep
REF
SYNC
N
Start position
Example of a reference point approach
(REFPT_TYPE=1):
• Start direction is plus.
• Position of the zero marker from the reference
point switch is set in the minus direction.
v
creep
REF
SYNC
N
Start position
R
-v
creep
v
rapid
Example of a reference point approach
(REFPT_TYPE=0):
• The start direction must be set in the plus
direction.
• Position of the zero marker from the reference
point switch is set in the plus direction.
• The reverse switch is more positive than the
reference-point switch.
REF
REV
v
creep
SYNC
-v
creep
N
Start position
R
–v
rapid
R = Direction
reversal
REF = Reference-point
switch
REV= Reversing
switch
Z = Encoder zero mark
SYNC = Synchronization was achieved.