Hello,

I'm currently operating a SINUMERIK 840D system equipped with the RunMyRobot option. I've been utilizing online tool compensation (TOFF) via synchronized actions to perform milling operations with real-time compensation (for example, to offset deviations of the robot end-effector during machining).

Below is a simplified snippet from my machining program (MPF file) with CYCLE832 activated:

...
TOFFON(X);
ID=3 WHEN TRUE DO $AA_TOFF[X] = $A_DBR[328] ; value which is coming from my PLC
...
G1 ...
G1 ...
etc...

The variables $MC_TOFF_VELO and $MC_TOFF_ACCEL have been configured with relatively high values, as the compensation signals sent during machining can be abrupt and require responsive application. I've also been tuning the parameter $MC_ADD_MOVE_ACCEL_RESERVE, which controls the acceleration margin reserved for overlaid motions. When this parameter is set to 0.2, the machining operation completes faster but with reduced accuracy. On the other hand, increasing the value to 0.9 results in significantly improved precision, though at the cost of slower execution.

Now for my actual question: At what stage in the motion pipeline is TOFF actually applied? Since the compensation cannot be applied instantaneously, I assume it must be processed further down the motion blocks (Look Ahead?). While testing a machining program, I logged several signals, including the encoder values for the geometry axis, the setpoint, and the override setpoint (which includes the tool compensation). I noticed that the encoder values lagged behind the setpoint by approximately 0.133 seconds. Does this imply that the tool compensation is applied to the setpoint with a delay of around 0.133 seconds into the future? Could this delay be reduced by setting a maximal number of blocks in the IPO buffer (SD42990 $SC_MAX_BLOCKS_IN_IPOBUFFER)? Would machine data $MC_LOOKAH_NUM_OVR_POINTS and $MC_LOOKAH_OVR_POINTS affect it as well (currently set to 1)?

Thank you for your help