Siemens SINUMERIK 840D sl Function Manual page 419

Output control
Whether or not the 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[<n>]
(output behavior of predefined auxiliary functions)
where <n> = system function index (0 ... 32)
● MD22035 $MC_AUXFU_ASSIGN_SPEC[<n>]
(output behavior of user-defined auxiliary functions)
where <n> = auxiliary function index (0 ... 254)
● MD11110 $MN_AUXFU_GROUP_SPEC[<n>]
(output behavior of the auxiliary functions in a group)
where <n> = group index (0 ... 63)
Bit
10
This behavior does not affect the display and does not affect variables
$AC_AUXFU_STATE[<n>], $AC_AUXFU_VALUE[<n>], and $AC_AUXFU_EXT[<n>].
The auxiliary functions are always regarded as collected after a block search, even though
they are not output to the PLC.
During collection, an auxiliary function that is not output after a block search also overwrites
an auxiliary function whose bit 8 is not set.
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 synchronized actions.
Note
The following auxiliary functions are not collected:
● Auxiliary functions which are not assigned to any auxiliary function group.
● Auxiliary functions which are assigned to the first auxiliary function group.
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 (Page 417)").
M19 behavior (position spindle)
After a block search, the last spindle positioning command programmed with M19 is always
carried out, even if other spindle-specific auxiliary functions are programmed between the part
program with M19 and the target block. Setting the necessary spindle enables must therefore
be derived from the interface signals of the traverse commands in the PLC user program:
DB31, ... DBX64.6/64.7 (traversing command minus/plus)
Basic Functions
Function Manual, 01/2015, 6FC5397-0BP40-5BA2
Value Meaning
0 Output during type 1, 2, and 4 block searches
1 No output during type 1, 2, and 4 block searches
H2: Auxiliary function outputs to PLC
8.13 Behavior during block search
419