Watchdog State Register; Battery Status Register; Nvram Address Register - Siemens SIMATIC IPC277G Operating Instructions Manual

Technical specifications
8.5 Hardware descriptions
8.5.5.4

Watchdog state register

Bit
7
6
5
4
3 to 0 Read/Write
8.5.5.5

Battery status register

The status of the CMOS battery is monitored; the status (two-tier) can be read from the
battery status register.
Meaning of the bits
Battery status register (read-only, address 404Dh)
Bit
7
8.5.5.6

NVRAM address register

NVRAM occupies a 512 KB memory address area that can be read via PCI registers.
Meaning of the bits
NVRAM address register
PCI register address:
NVRAM base address register
Address variable (depending
on the slot where NVRAM is
located)
100
Read/Write state Meaning of the bits
Read/Write Not used for watchdog
Read/Write Not used for watchdog
Write "1" Only Trigger Watchdog Timer I event. This bit is self-clearing.
Read/Write Watchdog Timer I status bit:
•
•
Not used for watchdog
6 5 4 3 2 1
0 0
0 1
1 1
0: Watchdog Timer I is running.
1: Watchdog Timer I issues time-out event.
Meaning
0
CMOS battery capacity is still sufficient.
CMOS battery capacity is exhausted (remaining capacity is
sufficient for approx. one month)
CMOS battery is empty
PCI register content:
NVRAM memory address (default
setting)
Address is assigned dynamically
(depending on device
configuration)
Length of the memory area
80000 h
Operating Instructions, 08/2021, A5E50059956-AA
SIMATIC IPC277G