Detailed Description
2.3 Continuous-path mode
Continuous-Path Mode, Exact Stop, LookAhead (B1)
Function Manual, 08/2005 Edition, 6FC5397-0BP10-0BA0
2-7
• If a positioning axis is declared to be the geometry axis, the previous block is terminated
at the interpolator end when the geometry axis is programmed.
• If a synchronized axis is programmed that was last programmed as a positioning axis or
spindle (initial setting of the special axis is positioning axis), the previous block is ended
at the interpolator end.
• If the transformation is changed, the block previously processed is terminated with the
active exact stop criterion.
• A block is terminated on interpolator end if the following block contains the switchover of
the acceleration profile BRISK/SOFT.
For more information about BRISK and SOFT:
References:
/FB1/ Description of Functions, Basic Machine; Acceleration (B2)
• If the "empty buffer" function is programmed, the previous block is terminated when the
selected exact stop criterion is reached.
Velocity = 0 in continuous-path mode
Regardless of the implicit exact stop response, the path motion is braked down to zero
velocity at the end of the block in cases where:
• Positioning axes have been programmed with syntax POS and have a travel time that
exceeds that of the path axes. Block change occurs when the "exact stop fine" of the
positioning axes is reached.
• The time taken to position a spindle programmed with syntax SPOS is longer than the
travel time of the path axes. The block change is carried out when the "exact stop fine" of
the positioning spindle is reached.
• The current block contains traversing commands for geometry axes and the following
block traversing commands for synchronized axes or, alternatively, the current block
contains traversing commands for synchronized axes and the subsequent block
traversing commands for geometry axes.
• Synchronization is required
Auxiliary function output during traversal
In continuous-path mode with auxiliary-function output during motion and short traversing
blocks, the path velocity is decelerated prior to PLC acknowledgment of the auxiliary
functions.
The axes are decelerated to standstill respecting the acceleration limits at the end of the
block. At the end of the block acknowledgment is awaited before motion can continue.
Acknowledgment during deceleration
Acknowledgment during deceleration accelerates the velocity back to the programmed path
velocity.
In order to prevent this happening in continuous-path mode, machine data:
MD10110 PLC_CYCLE_TIME_AVERAGE (maximum PLC acknowledgment time)
can be used to set a time for the CNC during which the PLC will safely acknowledge the
auxiliary functions for the CNC.
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