on your box acting as a router you will want to add a second ip in the 192.168.0.0/24 network and then it will route for you system-config-network will let you do it the devices with 192.168.0.0/24 address will need to have the router as the default gateway.
So do I add another network card to the box or do I add a second IP to my 10.10.10.1 nic in the machine? But I will need to change the default gateway in the PLC devices to be the IP I put on the server? So ideally I would add 192.168.0.1 to the 10.10.10.1 nic and then I'm good to go? -- -=/>Thom