Siemens SINUMERIK 840DE Programming Manual page 281

Note
Please note that the maximum permissible values of the machine manufacturer can be
exceeded with a higher acceleration rate.
Example
N50 ACC[X]=80
Meaning: Traverse the axis slide in the X direction with only 80% acceleration.
N60 ACC[SPI(1)]=50
Or
ACC[S1]=50
Meaning: Accelerate or decelerate spindle 1 with only 50% of the maximum acceleration.
The spindle identifiers SPI(...) and S... are identical in terms of function.
Acceleration override programmed with ACC
The acceleration override programmed with ACC[] is always taken into consideration on
output in system variable $AA_ACC. Readout in the parts program and in synchronized
actions takes place at different times in the NC processing run.
In the part program
The value described in the parts program is only considered in the system variables
$AA_ACC as described in the parts program, if ACC was not changed in the meantime by a
synchronized action.
In synchronized actions
The following thus applies: the value written to the synchronized action is only considered in
the system variables $AA_ACC as written to the synchronized action if ACC was not
changed in the meantime by a parts program.
The defined acceleration can also be changed via synchronized actions. See /FBSY/,
Synchronized Actions.
Example: N100 EVERY $A_IN[1] DO POS[X]=50 FA[X]=2000 ACC[X]=140
After RESET the last programmed value is retained. The current acceleration value can be
called with the system variables $AA_ACC[<axis>].
Fundamentals
Programming Manual, 10.2004 Edition, 6FC5 298-7AB00-0BP1
Feedrate Control and Spindle Motion
7.10 Percentage acceleration override (ACC option)
7-31