Siemens SINUMERIK 840D sl Function Manual page 857

Figure 13-11 FC18 input/output parameters
Asynchronous subprograms (ASUBs)
An ASUB can be used to activate arbitrary functions in the NCK. Before an asynchronous
subprogram can be started from the PLC, it must be ensured that it is available and prepared
by the NC program or by FB4 PI services (ASUB).
Once prepared in this way, it can be started at any time from the PLC. The NC program running
in one of the parameterized channels of FC9 is interrupted by the asynchronous subprogram.
An ASUB is started by calling FC9 from the user program by setting the start parameter to 1.
Note
If an asynchronous subprogram has not been prepared by an NC program or by FB4 (ASUB)
(e.g. if no interrupt no. has been assigned), a start error is output (StartErr = TRUE).
Read/Write NC variables
NCK variables can be read with FB GET while values can be entered in NCK variables with
FB PUT. The NCK variables are addressed via identifiers at inputs Addr1 to Addr8. The
identifiers (symbols) point to address data which must be stored in a global DB. To allow
generation of this DB, the PC software is supplied with the basic program with which the
required variables can be selected from a table, which is also supplied. The selected variables
are first collected in a second, project-related list. Command Generate DB creates a "*.AWL"
file which must be linked to the program file for the machine concerned and compiled together
with the machine program.
1 to 8 values can be read or written with a read or write job. If necessary, the values are
converted [e.g. NCK floating-point values (64-bit) are converted to PLC format (32-bit with 24-
Basic Functions
Function Manual, 01/2015, 6FC5397-0BP40-5BA2
P3: Basic PLC program for SINUMERIK 840D sl
13.10 Structure and functions of the basic program
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