On the 10, there is usually two ports, one on the MB and one on the operator panel, you can use the appropriate parameter to swap the port over, failing that you could trace the RS232 pins on the Honda socket and look for any IC close by that have 1488 or 1489 on them, I cannot remember if they use this common IC or not, but any IC connected to the port could be replaced as an attempt to cure it if you cannot find the other port.
Al.
CNC, Mechatronics Integration and Custom Machine Design
“Logic will get you from A to B. Imagination will take you everywhere.”
Albert E.