/diy/ - Do It Yourself

I'm trying to figure out a board that uses a 100 pin Xilinx CPLD and I've managed to basically find what each pin on all the connectors on the board do, where they go ,etc.
Now, one of the connectors had 2 pairs of pins coming from the CPLD through an RS422 driver and 5 pairs going to the CPLD through an RS422 decoder.
After much messing around and rewiring shit, I've figured out which pairs are RXD, TXD, CTS and RTS and have wired the board up to an RS422 to USB converter.
I know it's correct now cause when I type stuff into the serial terminal it feeds me back what I'm typing, every other combination of pairs didn't do that.

Anyway, I've no fucking idea what kind of commands to give this board, it doesn't print anything to serial on boot up and everything I've tried entering so far doesn't give me any response.

Is there anything like a dictionary attack of something that could keep feeding in random commands until it gets a response?

In case you're wondering, the board is not from a mass produced commercial product and the company that made the board has been bought by a company that is a direct competitor to the company that manufactured the unit so nobody wants to help anybody out with it.