i am trying to get a network redundancy (like Bonding in X20 PLC) for X90 PLC.
i am switching the IP address between the ETH port and the PWL port (defined as ethernet port), the switching work fine, but, the problem is that i am using OPC UA over the network, when i change between the ports the OPC UA client (Unexpert is losing the communication - attaching a picture). is there a way to overcome this problem and keep the OPC UA working when changing the ports? thank you.
As far as I know is that when you change the IP adres the network stack resets and every TCP connection is dropped. So this naturally results that OPCUA loses its connection.
So from the application you should build a automatic reconnect.
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yes’ i expected the OPCUA to reconnect to the correct address. do you have any practical advice how to restart the OPC_UA server or reconnect?
The OPCUA server should be directly reachable again nothing to restart.
But you are changing IP around..
So doing the following ?
START:
- ETH2 : 192.168.1.1
- ETH3 : 172.168.10.1 ( Something random but not in the subnet range of the other ETH interface)
Change in 2 steps:
- Set ETH2 to 189.23.2.1 ( Something random but not in the range of the ETH3 is currently in)
- Set ETH3 to 192.168.1.1
When you PING from your PC you should see that only temporary the connection is lost and then the reply should be back.
like i said the switch is working fine and i have ping . the problem is with the OPC UA which for some reason does not reconnect after the change ( no meter what i do except for PLC restart)
yes something like what you describe.
you can see in the image i attached it is not reconnecting.
Just a wild guess:
In which “mode” are you connecting? Do you have any “security” enabled / enforced?
To my knowledge the OPC-UA server generates certificates for a secure connection - which includes the IP … so if you change the IP, the certificates becomes invalid and UAExpert would refuse to connect … The message BadCommunicationError while OpenSecureChannel could point in that direction, too.
CHH
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I guess in UaExpert you have to manually reset the connection.
Like already mentioned, I do believe there is a unique fingerprint of each interface connected to the server certificate, which you have to accept.
For the PLC you can use an automatic detection of loss of network to initiate a UA_Disconnect followed by an immediate UA_Connect.
i do not change the IP address , i just alternate between the physical ports, so initially the ETH port has the correct IP, and if a disconnection is seen then i switch the IP between the ports so now the PLK port has the correct IP.
how can i reset the connection from Unexpert?
UA disconnect and UA connect are client functions, if i connect to PLC then maybe it is possible but if i go directly to SCADA system i am not sure this is possible.
currently no security features, in the future i will need to implement security also.