10 NC Start-Up with HMI Advanced
10.4 Memory configuration
Virtual SRAM (SW 2.3 and higher)
If more user memory is required than is available via the SRAM of the MCI
board, the function "Virtual SRAM" can be used with SW 2.3 and higher.
The "Virtual SRAM" function is activated via HMI Advanced (option) (see Sub-
section 10.10.2, Page 10-399).
During operation of the NCK, the memory area of the virtual SRAM is physically
located in the main memory (DRAM) of the PCU. When Windows NT is shut
down correctly, this memory area is written to the hard disk of the PCU as reten-
During start–up of the NCK, the "SRAM" data are loaded from the hard disk of
the PCU to the main memory (DRAM) of the PCU and made available to the
NCK again as virtual SRAM. The status of the "SRAM" corresponds to the sta-
tus at the time of last proper shutdown.
On loss of voltage or on deactivation of the PCU without proper shutdown of
Windows NT beforehand, all user data stored in the virtual SRAM will be lost. A
UPS system (see Subsection 1.1.8, Page 1-29) is therefore absolutely neces-
sary in conjunction with the virtual SRAM.
The Windows NT system settings stated below can generally prevent loss of
data in the event of a serious exception (Blue Screen) detected by Windows
The necessary Windows NT system settings are check during start/up of the
SINUMERIK 840Di. If setting are incorrect, a message box appears with the
The necessary Windows NT system settings have already been made for all
new SINUMERIK 840Di systems delivered. The following systems are excep-
– PCU50 333MHz / 500MHz with more than 128MB main memory
– PCU50 566MHz / 1,2GHz with more than 256MB main memory
With these systems, the relevant Windows NT system settings must be made
manually during the commissioning phase.
Siemens AG, 2003. All rights reserved
SINUMERIK 840Di Manual (HBI) – 06.03 Edition