Emerson Exchange 365

Hello,

I have a system that has the follows the recommended network architecture: Level 4 Network -> Corporate Firewall -> Level 3 DMZ -> Emerson Smart Firewall -> Level 2.5 Network -> DeltaV Workstations.

A 3rd party system exists on the L4 network that needs to communicate with DeltaV for SCADA control of a few devices. The catch is that the 3rd party system only communicates via MODBUS TCP, it has no capability for OPC. It is also a MODBUS master.

I have been trying to determine the best method to use when connecting the systems. I have come up with a few options but I don't really like any of them:

1. Kepware Server: Use Kepware as the MODBUS slave to OPC converter. Then I would use OPC MIrror on the existing OPC server to complete the connection.
   1. Install in the DMZ
   2. Install in the L2.5 Network
   3. I'm not a fan of adding a server for communications; it is just one more server to manage as it provides a nice attack surface.
2. A hardware device, such as a Red Lion. This device is capable of being a simple MODBUS Slave to OPC converter. Then I would use OPC MIrror on the existing OPC server to complete the connection. 
   1. Install in the DMZ
   2. Install in the L2.5 Network
   3. I like this a little better, but it's not really an integrated solution in my mind.
3. Connect a dedicated VIM to the L2.5 Network
   1. Don't shoot me; it was just a thought!
   2. Could this be legitimate?
   3. I have no desire to connect the VIM network to the L2.5 network.
4. ???

Thank you,

Dave