Siemens SINUMERIK 840D sl Function Manual page 49

The current value of the tool length compensation can be read via the system variable
$AA_TOFF_VAL.
Note
An evaluation of the variables $AA_TOFF_VAL is only useful in conjunction with an active
orientation transformation or an active tool carrier.
Examples
Selecting the online tool length compensation
Machine data for online tool length compensation:
● MD21190 $MC_TOFF_MODE = 1
● MD21194 $MC_TOFF_VEL[0] = 10000
● MD21194 $MC_TOFF_VEL[1] = 10000
● MD21194 $MC_TOFF_VEL[2] = 10000
● MD21196 $MC_TOFF_ACC[0] = 1
● MD21196 $MC_TOFF_ACC[1] = 1
● MD21196 $MC_TOFF_ACC[2] = 1
Activate online tool length compensation in the part program:
Program code
N5 DEF REAL XOFFSET
; Activate orientation transformation
N10 TRAORI
; Activate tool length compensation in the Z direction
N20 TOFFON(Z)
; Tool length compensation in the Z direction: 10 mm
N30 WHEN TRUE DO $AA_TOFF[Z] = 10
G4 F5
...
; Static synchronized action: Tool length compensation in the X direction
; corresponds to the position of the X2 axis in the WCS
N50 ID=1 DO $AA_TOFF[X] = $AA_IW[X2]
G4 F5
...
; Note: Current total tool length compensation in the X direction
N100 XOFFSET = $AA_TOFF_VAL[X]
; Retract the tool length compensation in the X direction to 0
N120 TOFFON(X, -XOFFSET)
G4 F5
Synchronized actions
Function Manual, 08/2018, 6FC5397-5BP40-6BA2
3.3 System variables for synchronized actions
Detailed description
49