Siemens SIMATIC FM 351 Manual page 89

– after the FM 351 has returned the "PEH" signal,
– when the monitoring time is exceeded,
– when the speed falls below the stationary speed.
If the drive leaves the stationary range without a valid travel job, the FM 351
indicates the operating error "stationary range exited" (error number 6).
Target Approach
In the "absolute/relative incremental approach" modes, the target approach begins
when the switch-off point is reached. At this point, the drive is turned off and the FM
351 starts the monitoring functions.
Depending on the monitoring functions you have activated, there are various
situations in which the return signal "PEH (POS_RCD)" is generated. Positioning is
aborted as soon as the generation of the "PEH (POS_RCD)" return signal does not
take place.
1. You have set the following parameters:
– Target range (TRG_RANGE) > 0
– Stationary speed (ZSPEED_L) > 0
– Monitoring time (MON_TIME) > 0
PEH is generated when the speed falls below the stationary speed and the
target range is reached. Which condition is satisfied first is irrelevant.
PEH is not generated when the actual value does not reach the target range
within the monitoring time or the target range is passed without the speed falling
below the stationary speed.
–1000 mm
v
t
1
Switchover difference plus
2 Switch-off difference plus
Stationary range
3
Figure 9-1
FM 351 Positioning Module
C79000-G7076-C351-02
0
1
creep
v
stationary speed
= monitoring time
m
4
5
6
Final Target Approach of an Incremental Approach
Target
1000 mm
4
2
5
6
t
m
Target range
Stationary speed reached
Target range reached with v
Modes and Jobs
3
: PEH is set
still
9-3