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If it does prove to be a problem, you could look into either RS422/485 converters, or having just done a quick google, you can get RS232 repeaters/range extenders.

The same google search threw up...

Try it an see - 50 meters is not a hard limit. You could test with a multi-meter how the existing cable is wired, but to extend it all you need is a cable that connects pin 1 to pin 1 ... pin n to...

Not recommending, just looking for relatively low budget machine design that gets near your spec.

self build
http://frankieflood.blogspot.co.uk/2013/02/cncrp-router.html

ready built...