Continuous Path Mode; General - Siemens SINUMERIK 808D Function Manual

● Exact traversing of the contour on the basis of the criterion (e.g. exact stop fine) can deviate from the programmed
contour in order to achieve faster machining.
● An absolutely constant velocity is required.
Activate exact stop
The "Exact stop" function can be selected in the NC part program by command G60 or G9. G60 is modal, G9 is non-modal.
G9 is used if continuous path mode is to be interrupted. Both exact stop functions only function with the selected exact stop
criterion (G601, G602). The "exact stop" function is de-selected with the continuous path mode function (G64).
Exact-stop criteria
● Exact stop fine: G601
This criterion is applied to monitor whether the actual/setpoint position deviation of the axis has remained within a
specific distance. The value of the permissible distance is stored in MD36010 STOP_LIMIT_FINE (exact stop fine)
● Exact stop coarse: G602
Functions as exact stop fine, although the monitoring window is stored in MD36000 STOP_LIMIT_COARSE (exact stop
coarse). To permit a faster block change than with the exact stop fine criterion, the exact stop coarse criterion is set to be
larger than the exact stop fine criterion.
Block change depending on exact-stop criteria:
Interpolator end
Interpolator end is achieved when the interpolator has calculated the setpoint velocity of the axes from zero for an
interpolation cycle. However, the actual positions of the path axes have not reached the target (following error).
Irrespective of continuous-path mode or the active exact-stop criteria for the exact-stop function, "interpolator end" transfers
the auxiliary functions present in the block to the PLC if they are to be output after the end of motion.
5.4

Continuous path mode

5.4.1

General

In continuous path mode, the path velocity is not decelerated for the block change in order to permit the fulfillment of an
exact stop criterion. The objective of this mode is to avoid rapid deceleration of the path axes at the block-change point so
that the axis velocity remains as constant as possible when the program moves to the next block. To achieve this objective,
the "LookAhead" function is also activated when continuous path mode (G64) is selected.
Continuous path mode causes:
● Rounding of the contour.
● Shorter machining times through elimination of braking and acceleration processes that are required to comply with the
exact-stop criterion.
● Improved cutting conditions as the velocity is more uniform.
The continuous-path mode is suitable if a contour is to be traversed as quickly as possible.
Continuous-path mode is suitable if:
● A contour is to be traversed precisely.
● An absolutely constant velocity is required.
Function Manual
01/2017
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