Freelance MBTCP_M.Conn
Hello Dieter
just another question to the Modbus TCP: According to manual the system variable MBTCP_M.Conn hold the number of active connections.
Considering a setup with redundant CPU and redundant slaves, I observe ther following
- the value of MBTCP_M.Conn is '1' or '2'. I do not understand when it is '1' and when '2'. In our system I can see, that the inactive slave does not get any Modbus Requests, so I would assume, Freelance CPU connects to the inactive slave just after the active one gets lost.
- the value drops to 0 whenever I interrupt the active line, irrespective that the inactive line is intact and available. After few seconds it comes back to '1' when the backup line is activated.
I tried to use the value to implement an application based CPU switchover, and it is possible using a delay timer. But still I'd like to understand the real meaning of this variable.
Can you give me more information here?
Thanks & best regards
Ulrich
HIMA Brühl
just another question to the Modbus TCP: According to manual the system variable MBTCP_M.Conn hold the number of active connections.
Considering a setup with redundant CPU and redundant slaves, I observe ther following
- the value of MBTCP_M.Conn is '1' or '2'. I do not understand when it is '1' and when '2'. In our system I can see, that the inactive slave does not get any Modbus Requests, so I would assume, Freelance CPU connects to the inactive slave just after the active one gets lost.
- the value drops to 0 whenever I interrupt the active line, irrespective that the inactive line is intact and available. After few seconds it comes back to '1' when the backup line is activated.
I tried to use the value to implement an application based CPU switchover, and it is possible using a delay timer. But still I'd like to understand the real meaning of this variable.
Can you give me more information here?
Thanks & best regards
Ulrich
HIMA Brühl
Asked 1 month ago
Voted best answer
1
The .Conn variable tells you over which of the two IP addresses the master communicates with the slave. It is 1 if the master communicates via the upper IP. If you then toggle the slave interface the .Conn goes to 2. IF you toggle the slave back .Conn will show 1 again. If no connection to the slave exists the .Conn variable has the value of 0.
The master has only a connection to one of the IP addresses at a time. It only switches to the second slave address if the connection to the primary slave address gets lost.
The master has only a connection to one of the IP addresses at a time. It only switches to the second slave address if the connection to the primary slave address gets lost.
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