Siemens SINUMERIK 840DE Programming Manual page 196

Path Action
5.3 Continuous-path mode (G64, G641, G642, G643, G644)
3. Rounding is not parameterized. This occurs with G641 when ...
With G642/G643, when all axis-specific tolerances equal zero.
Look Ahead speed control
In continuous-path mode with G64 or G641, the control automatically detects the velocity
control in advance for several NC blocks. This enables acceleration and deceleration across
multiple blocks with almost tangential transitions.
Look Ahead is particularly suitable for the machining of movement sequences comprising
short traverse paths with high path feedrates.
The number of NC blocks included in the Look Ahead calculation can be defined in machine
data.
Note
Look Ahead across more than one block is an option.
5-14
– MD 20490: IGNORE_OVL_FACTOR_FOR_ADIS can be set to TRUE to set this
behavior for G641 and G642.
– ADISPOS == 0 in G0 blocks (default).
– ADIS == 0 in non-G0 blocks (default).
– For transition from G0 to non-G0 or non-G0 to G0, the smaller value of ADISPOS and
ADIS applies.
Programming Manual, 10.2004 Edition, 6FC5 298-7AB00-0BP1
Fundamentals