Download Siemens SIMATIC PANEL PC 877 Operating instructions

Functions
10.4 Fan monitoring
10.4
Fan monitoring
The function monitors operation of the enclosure and power supply fans. When a fan fails,
the following reactions are triggered:
Response
Option
The DiagBase or DiagMonitor software is enabled None
The fan fault is retained in memory until the cause of the fan failure has been rectified and
the error is reset by taking one of the following measures:
● Acknowledgment of the error message by the monitoring software
● Restart of the device
10.5
SRAM buffer memory
In order for applications to store data following a power failure, the motherboard features
battery-buffered SRAM. If the supply voltage fails for more than 20 ms for the AC power
supply or more than 5 ms for the DC power supply, then you will be informed about this
situation by the NAU signal.
At least 10 ms is available to copy the data to the buffered RAM. During this time, 128 Kb
can be saved with a full load and even more with a smaller configuration, in other words, a
lesser load. A maximum 2 MB memory window is displayed via a PCI address register. The
base address is initialized by the BIOS.
A corresponding function is implemented there for using the SRAM under WinAC RTX.
NOTICE
If replacement of the battery takes longer than 30 seconds, the data saved in the CMOS
RAM and in the buffered SRAM is lost.
Note
The buffer memory SRAM is available only with devices with PROFIBUS or PROFINET
interfaces.
10.6
Battery monitoring
The installed buffer battery has a service life of at least 5 years. The status can be checked
with two-tier battery monitoring. The information can be read from an I/O register and
evaluated.
When the first warning level is reached, the remaining service life of the battery for buffering
CMOS data amounts to at least 1 month.
SIMATIC IPC677C
Operating Instructions, 05/2010, A5E02722710-01
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