Siemens SINUMERIK 840D sl Function Manual page 534

Detailed description
2.12 Block search
2.12 Block search
2.12.1 Behavior on block search with calculation
Function
Block searches with calculation collect up auxiliary functions on a groupspecific basis. The
last auxiliary function in each auxiliary function group is output after NC-START, before the
actual reentry block, in a separate part program block that has the following output behavior:
• Output duration one OB1 cycle (normal acknowledgment)
• Output prior to motion
Output control
Whether or not the corresponding auxiliary function is output to the PLC after a block search
can be configured via bit 8 of the machine data:
MD22080 $MC_AUXFU_PREDEF_SPEC[index] (output specification)
MD22035 $MC_AUXFU_ASSIGN_SPEC[index] (output specification)
MD11110 $MN_AUXFU_GROUP_SPEC[index] (auxiliary function group specification)
This behavior does not affect the display and does not affect variables
$AC_AUXFU_M_STATE[n], $AC_AUXFU_M_VALUE[n], and $AC_AUXFU_M_EXT[n]. The
auxiliary function is always regarded as collected after a block search, even though it is not
output to the PLC. An auxiliary function that is not output after a block search also overwrites
an auxiliary function whose Bit 8 is not set during collection. The user can scan the collected
auxiliary functions after a block search and, under certain circumstances, output them again
by means of the subprogram or synchronous actions.
Auxiliary function without auxiliary function group
Auxiliary functions that are not assigned to an auxiliary function group are not collected up.
Auxiliary functions of auxiliary function group 1
Auxiliary functions of auxiliary function group 1 are never collected up.
Overstorage of auxiliary functions
After completion of a block search, the collected auxiliary functions are ouput on the next
NC-START. If it is necessary to output additional auxiliary functions, they can be added via
the "overstore" function. See Section: Response to overstore.
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Basic logic functions: Auxiliary Function Output to PLC (H2)
Function Manual, 11/2006, 6FC5397-0BP10-2BA0