Siemens SINUMERIK 828D Programming Manual page 567

Read MD and SD values at the preprocessing time
They are addressed from within the synchronized action using the $ characters and
evaluated by the preprocessing time.
ID=2 WHENEVER $AA_IM[z]<$SA_OSCILL_REVERSE_POS2[Z]-6 DO $AA_OVR[X]=0
;Here, reversal range 2, assumed to remain static during operation, is addressed for
oscillation.
Read MD and SD values at the main run time
They are addressed from within the synchronized action using the $ characters and
evaluated by the main run time.
ID=1 WHENEVER $AA_IM[z]<$$SA_OSCILL_REVERSE_POS2[Z]-6 DO $AA_OVR[X]=0
;It is assumed here that the reverse position can be modified by a command during
the machining
Write MD and SD at the main run time
The currently set access authorization level must allow write access. The active states are
listed for all MD and SD in References: /LIS/, Lists (Book 1).
The
Example
Program code
ID=1 WHEN $AA_IW[X]>10 DO
$$SN_SW_CAM_PLUS_POS_TAB_1[0]=20
$$SN_SW_CAM_MINUS_POS_TAB_1[0]=30
Job planning
Programming Manual, 07/2010, 6FC5398-2BP40-0BA0
and to be written must be addressed preceded by
MD SD
Motion synchronous actions
10.3 Main run variables for synchronized actions
.
$$
Comments
; Changing the switching position
of software cams. Note: The
switching positions must be
changed two to three
interpolation cycles before they
reach their position.
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