Siemens sinumerik 840D sl Function Manual page 368

Detailed description
2.7 Extended stop and retract (ESR)
Measuring system
For the drive there is no reference to the NC geometry system. On the NC side, the unit
system of the motor measuring system is only known if it is used as a position measuring
system.
Retraction path
The retraction path is therefore specified for the drive, using the following geometry-neutral
data:
• Speed setpoint, direction (leading sign):
• Travel time:
The drive traverses the programmed "retraction path" using a time-controlled speed setting
made internally in the drive.
It must be activated by the system variable $AA_ESR_ENABLE and triggered with
$AN_ESR_TRIGGER.
The "retraction path" really traversed in the event of an error depends on the current actual
speed at the time that the emergency retraction was started and can deviate slightly from the
programmed path as the drive does not monitor a path (no interpolation).
After this process speed setpoint zero is preset for the retraction axes too and a standstill
occurs at the current limit (comp. drive-independent stop).
Note
Drive independent emergency retraction is only effective when the bit "Impulse deletion" of
the following machine data is set to OFF:
MD1612 $MD_ALARM_REACTION_POWER_ON
and
MD1613 ALARM_REACTION_RESET
When emergency retraction is active, its parameters cannot be modified. Although data are
transferred to the drive, they are not accepted. There is no message to the user.
148
MD1639 $MD_RETRACT_SPEED
MD1638 $MD_RETRACT_TIME
Special functions: Axis Couplings and ESR (M3)
Function Manual, 11/2006, 6FC5397-2BP10-2BA0