Go to diagnostics and press the menu key PLC I/F or the one that has I/F and some Japanese characters. You should see a bunch of 1's and 0's on this page. The cursor will be blinking at the bottom. Type 1001 and move you cursor over near mode and type M. Press input. Now go to parameters where you will be in machine parameters. The menu key at the bottom should say Base. Page forward until you see a parameter lang and type a 1 and input. Power off and on. Should be about the 4th page in under base if you have a 9 inch screen.
RS232 port is located on the QX521 card or if color screen the QC524 card. There should be a cable on there that breaks out to a RS232 port. On OKK's it's usually located on the side of the operation panel under a small cover. If no cable then you will have to manufacture one. Look on meau.com downloads and find the manul for M500 connection. It will show you what you need for that cable.