I do not believe that RS-232 were ever specified above 19.2k.

Everything you want to know (and more) about 232/422/485 can be found at http://www.national.com/apnotes/A...rface.html .

Since you are concerned about distance, I would recommend that you use RS-485 instead, at any speed it reaches so much farther. One of the appnotes at the above reference has a speed vs distance graph for 485.

Plug a 232 to 485 converter from www.bb-elec.com in your stupid (its 232) PC port and GO.

Have fun,

Erik