Siemens SIMATIC S7-1200 CP 1243-8 IRC Operating Instructions Manual page 99

The path of a connection is specified as a combination of the used interfaces of the CP and
the status of the connection path.
● Byte assignment
The byte is assigned as follows:
– Two bits for the interface of the main path
– Two bits for the interface of the substitute path
– Two bits for the status of the main path
– Two bits for the status of the substitute path
● Configured interface
The interfaces of the CP are designated 0 and 1 in the following table. The names have
the following meaning:
– 0
– 3
Other possible interfaces (1 or 2) are not relevant for the CP.
● Path status
– Main path = 1st path, coding by bits 0 and 1
– Substitute path = 2nd path, coding by bits 2 and 3
CP 1243-8 IRC
Operating Instructions, 02/2018, C79000-G8976-C385-03
Bit 6 + 7
Configured interface
No. for substitute path
Ethernet interface
WAN interface
Status bit 5 / Status bit 4 /
bit 7 bit 6
0 0
0 1
1 0
1 1
Status bit 1 Status bit 0
/ bit 3 / bit 2
0 0
0 1
1 0
1 1
Bit 4 + 5
No. for main path
Meaning
Coding for the Ethernet interface (0)
- not relevant -
- not relevant -
Coding for the WAN interface (3)
Meaning of bit 1 / bit 3
Path not current
Path not current
Path current
Path current
4.11 Communication with the CPU
Bit 2 + 3
Path status
Substitute path (2nd Main path (1st path)
path)
Meaning of bit 0 / bit 2
Subscriber not reachable
Subscriber reachable
Subscriber not reachable
Subscriber reachable
Configuration
Bit 0 + 1
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