Alright well here goes. My dad asked me on Friday if I would look into setting his CNC machines up on a network for him. He said if I did he would pay for half of my new computer.
All 6 machines are connected by a cable for RS232 ports. His current setup is he has a computer in the front of his shop connected with the cable and then he manually connects the other end to whatever machine he wants to transfer the program file to.
My idea was to find a way to have all 6 machines connected to a router so he could just transfer files without having to switch the cable to a new machine every time a new program needed to be transferred.
No, you don't know what you're talking about. In your original post you asked about a router which implies networking (and you posted in the Networking forum). I most certainly know what Computer Numerical Control is since I worked for a CAD/CAM software company for 20 years. Next time try asking the correct question.
If all they have are serial port interfaces your best bet would be to find some kind of serial port switch. Something like http://sewelldirect.com/serial-db9-manual-switch-4.asp should work but a 6 selection. Get more cables and just leave them hooked up all the time. If the cnc machines do not have any kind of expansion ports that you could put a nic in, I dont think you can network them with normal network protocols.
You may be able to get by with a RS-232 to Ethernet convert, then buy a ethernet switch to connect all the cabling. The only problem I see would be that you'll need multiple RS-232 ports on one single computer for your scenario to work as you want.
Also I stumbled across this as well, it looks like just what you need as well. http://www.nti1.ca/serial-ip.html Would help very much in connecting those CNC machines to a standard Ethernet TCP/IP network.