from the Dualtech department...
Modbus Two Masters
Communications systems and equipment. topic
Posted by Leandro Ribeiro on 8 March, 2010 - 3:52 pm
Can I connect two masters for one slave modbus tcp?
Equipment Phoenix ILC150 ETH


Posted by Mark on 9 March, 2010 - 9:36 am
Hello,

Assuming the slave will allow more than one connection, which most allow, yes.

There is normally a maximum concurrent connection count for a slave but is it normally more than 2.

Good luck,

Mark
http://www.peakhmi.com/


Posted by Ian Goldby on 9 March, 2010 - 10:19 am
It depends on the slave, but probably yes you can.

Each Modbus conversation requires a separate TCP connection to the Modbus slave. If the Modbus slave can accept multiple simultaneous connections then yes, it can be accessed simultaneously by multiple masters.

You might also get away with a single connection if each master opens and closes its connection for every Modbus transaction. Some masters do this. Others hold their connection open.


Posted by scadametrics on 9 March, 2010 - 3:24 pm
Yes. As long as the slave will support multiple simultaneous sockets (which it should).

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