The Male 9-Pin D connector on the back of the Mx200 serves two purposes, support for a numeric keypad/footswitch and serial data communications.  Because of this, the pinout wiring is different from that of a standard RS232 connector.  

You can buy a specially wired MX200 Serial Cable from us. The part number is 11B12176-MX200.  

Or you can also wire the RS232 connector yourself.  The Mx200 only uses Pins 2 and 3 for Rx and Tx, and pin 5 as the common.  See the pinouts below: