Siemens SINUMERIK 840D Function Manual page 178

V1: Feedrates
5.4 Feedrate control
Percentage acceleration override (ACC)
In a part program or synchronized action, the acceleration specified in machine data:
MD32300 $MA_MAX_AX_ACCEL (maximum axis acceleration)
can be changed in a range from 0% – 200% using the ACC command.
Syntax:
ACC[<axis>]=<value>
Meaning:
ACC:
<Axis>:
<value>:
The actual axial acceleration value can be read via the system variable $AA_ACC. It is
determined by:
$AA_ACC[<axis>] = (MD32300 $MA_MAX_AX_ACCEL[<axis>]) * ACC[<axis>] / 100
MD32320 $MA_DYN_LIMIT_RESET_MASK can be used to specify the basic setting of the
value programmed with ACC for a channel reset or end of part program M30.
Note
The acceleration override programmed with ACC can be read using the system variable
$AA_ACC. However, $AA_ACC is read in the part program at a different time than when
reading in a synchronized action.
The system variables $AA_ACC only contain the value programmed in the part program with
ACC if, in the meantime, the acceleration override was not changed by programming ACC in a
synchronized action. The same applies for the reverse situation.
Percentage acceleration override and main run axes
Depending on whether the system variable $AA_ACC is read in the part program or
synchronized action, the value for the acceleration override programmed with ACC is output for
the NC axes or main run axes (command axes, PLC axes, asynchronous oscillating axes, etc.).
For correct results, system variable $AA_ACC must therefore always be read at the same
location (part program or synchronized action) from where the acceleration override was
programmed with ACC.
Examples:
Writing ACC in a part program:
N80 G01 POS[X]=100 FA[X]=1000 ACC[X]=90 IPOENDA[X]
Writing ACC in a synchronized action:
N100 EVERY $A_IN[1] DO POS[X]=50 FA[X]=2000 ACC[X]=140 IPOENDA[X]
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Keyword for the programming of the percentage acceleration override
Name of the channel axis or spindle
Acceleration change in percent relative to MD32300
Value range: 0 ... 200
Axes and spindles
Function Manual, 06/2019, A5E47437747B AA