8
8-6
FM 351 Positioning Function Module
EWA 4NEB 720 6001-02
Table 8-2 Drive Data, continued
Machine Data and
Assignment
Description
Standstill range
0 mm to
1 000 000.000 mm at a
resolution w
1
m
/
incr.
0 mm to
100 000.000 mm at a
resolution t
1
m
/
incr.
The standstill range is used for monitoring for standstill. Whether the drive remains
stationary at the approached position or drifts away is monitored.
If the standstill range is left, an error is signaled. The standstill range is monitored:
For all targets which you approach with the FM 351. Monitoring starts after the
FM 351 has signaled Position reached.
For traveling without a target if the momentary velocity is lower than the standstill
velocity.
For a value 0 the standstill monitoring is switched off.
Rules
During entry take note of the following rules:
The standstill range is placed symmetrically about the relevant target position.
Target position – 1/2 Standstill range Target position Target position + 1/2
Standstill range
Also, pay attention to Chapter 2.3 that shows the target run-in and the separate moni-
toring features and messages.
Standstill velocity
0 mm to
100 000.000
mm
/
min
The standstill velocity acts as the reference velocity. If the actual value reaches the
standstill velocity during a travel movement to a target and the drive is located in the
target range, then Position reached is set.
The positioning process is then terminated successfully.
The accuracy of positioning increases when the value of the standstill velocity is re-
duced.
Monitoring time
0 = No monitoring
1 to 100 000 ms
The monitoring period monitors:
The axis movement.
The actual value must have changed at least by one increment (resolution displace-
ment) within the monitoring period.
The monitoring period starts with the beginning of a positioning process.
The target run-in.
The target range must be reached during the monitoring period.
The monitoring period starts when the switch-off difference is reached.
Actual monitoring period
For the monitoring period you can specify all values from the defined range.
0: The monitoring is switched off.
1 to 100 000 ms: The FM 351 rounds the specified period up to a multiple of 8 ms.
Note that a difference of a maximum of 7 ms between your specified value and the
actual value used can occur. This difference is the more important the shorter the speci-
fied monitoring period is.
Therefore, enter the monitoring period preferably on an 8 ms pitch.
Machine Data and Increments
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