Siemens SINUMERIK 840D sl Function Manual page 719

2.9.8 Execution from external subroutines
Function
Individual machining steps for producing complex workpieces may involve program
sequences that require so much memory they cannot be stored in the NC memory.
In such cases, the user has the option of executing the program sequences as subroutines
from an external program memory in the "Execution from external source" mode with the
help of the EXTCALL part program instruction.
Preconditions
The following preconditions are applicable to the execution from external subroutines:
• The subroutines must be accessible via the directory structure of the operator interface.
• A reloading memory (FIFO buffer) must be reserved for each subprogram in the dynamic
Parameterization
The path for the external subprogram directory can be preset using setting data:
SD42700 $SC_EXT_PROG_PATH (Program path for the EXTCALL external subprogram
call)
The entire path of the program to be called along with the subprogram path or identifier
specified during programming is derived therefrom.
Basic logic functions: Mode group, channel, program operation, reset response (K1)
Function Manual, 11/2006, 6FC5397-0BP10-2BA0
NC memory.
Detailed description
2.9 Program control
161