I have been tasked with developing a centralized server that will communicate with many Samba PLCs around the world. Specifically, I need to ensure that the server can contact any PLC and 1) get a copy of the current values or 2) instruct the PLC to change a value. I want to ensure that the PLCs only communicate with the server, no other computers.
The data itself is not considered secret, so the fact that VisiLogic does not appear to offer encryption is not a problem. But, it is critical that only the server be allowed to update PLC values. It is simply unacceptable that another person could connect and update values, even if it would take quite the effort to accomplish that goal. Is there any way to ensure that the PLC's will only respond to requests/instructions from our centralized server? If I send a password, as a message, that password would not be encrypted, so others could see and use it. Is there anyway to securely connect to a Samba PLC, using VisiLogic? The server will know the PLC name and the IP Address, but once again, this would be transmitted unencrypted. Is there a way to program the PLC's to only accept connections from certain IP Addresses?
In summary, I want to ensure that the PLCs will listen for communication from our server, they will send current values when requested, they will update their values when told, and they will ignore any requests from others. Is this possible?
Any suggestions are greatly appreciated.