NC and PLC
Uninterruptible power system (UPS)
Siemens AG, 2003. All rights reserved
SINUMERIK 840Di Manual (HBI) – 06.03 Edition
If Windows NT is shut down not correctly, the Windows NT installation can be
damaged so that the SINUMERIK 840Di can no longer be operated.
On correct shutdown of Windows NT the following occurs:
– The SINUMERIK 840Di components NC and PLC are terminated cor-
– The NC and PLC user data in the SRAM of the MCI board and on the
hard disk of the PCU are backed up.
If the PCU is switched off without Windows NT having been correctly shut down,
with the POWER FAIL functionality or the SINUMERIK 840Di:
– end NC and PLC correctly
– save the NC and PLC user data in the SRAM of the MCI board.
The NC and PLC user data cannot be backed up on the hard disk of the PCU.
If you switch off the PCU without first having correctly shut down Windows NT,
please observe the following:
1. Data consistency of the NC and PLC user data can only be ensured if the
power supply of the PCU is at least 24V.
2. In the remaining time left by the internal power backup, Windows NT can no
longer be ended correctly. This implies the risk that the Windows NT instal-
lation can be damaged so that the SINUMERIK 840Di can no longer be run.
It is therefore urgently recommended to use an uninterruptible power sys-
tem (UPS) (see Subsection 1.1.8, page 1-29).
3. If the MCI board or its backup battery is replaced after the PCU has been
switched off, this will result in a data loss of the user data battery-backed on
the SRAM of the MCI board. How to proceed further: see Subsection 6.3.4,
The PCU has POWER FAIL detection that, in conjunction with the NC system
software, ensures that on a loss of voltage or power-off of the PCU without Win-
dows NT first having been shut down correctly the NC and PLC user data are
backed up in the SRAM of the MCI board.
However, in the remaining time left by the internal power backup, Windows NT
can no longer be ended correctly.
1 General on the SINUMERIK 840Di
1.1 Overview of SINUMERIK 840Di
Operator Components, Manual
Chapter: PCU 50