Technical specifications
8.5 Hardware descriptions
SIMATIC IPC277G
Operating Instructions, 08/2021, A5E50059956-AA
99
8.5.5
Input/output address areas
8.5.5.1
Overview of the internal module registers
The following addresses are used for the internal registers:
Addresses
Input/output unit
SIO logic device 8 CR F0h
Watchdog control register (Page 99)
SIO logic device 8 CR F1h
Watchdog counter register (Page 99)
SIO logic device 8 CR F2h
Watchdog state register (Page 100)
SIO logic device 7 CR FDh
Battery status register (Page 100)
For more information and reference code for accessing to Super IO, contact Siemens
Technical support.
8.5.5.2
Watchdog control register
Bit
Read/Write
state
Meaning of the bits
0
Read/Write
Watchdog Timer I Pulse or Level mode select:
•
0: Pulse mode
•
1: Level mode
1
Read/Write
Not used for watchdog
2
Read/Write
Not used for watchdog
3
Read/Write
Select Watchdog Timer I count mode.
•
0: Second Mode.
•
1: Minute Mode.
4 to 7
Reserved
8.5.5.3
Watchdog counter register
Bit
Read/Write
state
Meaning of the bits
0 to 7
Read/Write
Watch Dog Timer I Time-out value. Writing a non-zero value to the
register causes the counter to load the value into the Watch Dog Counter
and start counting down. The accuracy of watchdog timer I about one
cycle deviation. Non-zero value will be reloaded to the Watch Dog Counter
and the countdown resumes. Reading the register returns the current
value in the Watch Dog Counter but not the Watch Dog Timer Time-out
value.
•
00h: Time-out Disable
•
01h: Time-out occurs after one cycle time, the cycle time is based on
LD8 CRF0, bit[3], by analogy.
