Siemens SIMATIC S7-1200 CP 1243-8 IRC - Page 99

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