Position-Time Cams - Siemens SINUMERIK 840D sl Function Manual

Software cams, position switching signals (N3)

9.4 Position-time cams

9.4 Position-time cams
Position-time cams
The term "position-time cam" refers to a pair of software cams that can supply a pulse of a
certain duration at a defined axis position.
Solution
The position is defined by a pair of software cams.
The pulse duration is defined by the lead/delay time of the plus cam.
Machine data can be used to specify that cam pairs with:
minus cam position = plus cam position
are to be processed as position-time cams.
Properties of position-time cams
● The pulse duration is independent of the axis velocity and travel direction reversal.
● The pulse duration is independent of changes in the axis position (Preset).
● Activation (rising signal edge) takes place only when the cam position is crossed.
● A lead/delay time is operative for the minus cam and causes a time displacement of the
● Activation (ON edge) and pulse duration are independent of the travel direction.
● The cam is not deactivated if the cam position is crossed again when the cam is active
● The cam time (pulse width) is not interrupted and the cam time not restarted when the
Settings
The following settings must be made to program a position-time cam:
● Position
702
Moving the axis position (e.g. PRESET) does not trigger an activation.
pulse.
(direction reversal).
cam position is crossed again.
This behavior is particularly relevant with respect to modulo axes, i.e. if the cam time is
greater than the modulo range crossing time, the cam is not switched in every revolution.
The position must be defined by a cam pair with which the minus cam position is equal to
the plus cam position.
This is specified by setting data:
SD41500 SW_CAM_MINUS_POS_TAB_1
to
SD41507 SW_CAM_PLUS_POS_TAB_4.
Function Manual, 01/2008, 6FC5397-1BP10-3BA0
Extended Functions