Trying to download a program from a dos based program onto a Wasino lathe with a 21i-T fanuc control, but I keep getting a 087 buffer overflow alarm. I dont know what that means or how to troubleshoot it. (And i dont have the manuals)

Using:
Windows XP computer with dos based NC program
USB to 9pin to 25pin cable
bit rate: 4800
bit length:7
parity: E
stop bit: 1

i dont know much about connecting to CNC machines, so any information would be useful.