Siemens SINUMERIK 840D sl Operating Manual page 606

Managing programs
12.14 EXTCALL
NOTICE
Possible interruption when executing from USB FlashDrive
Direct execution from a USB-FlashDrive is not recommended.
There is no protection against contact problems, falling out, breakage through knocking or
unintentional removal of the USB-FlashDrive during operation.
Disconnecting it during operation will result in immediate stopping of the machining and,
thus, to the workpiece being damaged.
606
Software options
To display the "Local drive" softkey, you require the "Additional HMI user
memory on CF card of the NCU" option (not for SINUMERIK Operate on
PCU50 / PC).
Machine manufacturer
Processing EXTCALL calls can be enabled and disabled.
Please refer to the machine manufacturer's specifications.
Operating Manual, 03/2013, 6FC5398-7CP40-3BA1
Milling