Has anyone ever tried to interface a Pelco CCTV keyboard to Mach? This seems like it wouldd be perfect as a pendant controller. It speaks ASCII, uses RS422 (and RS232 I think) interfacing, and it's pretty well documented. Model is KBD300A

http://reviews.cnet.com/Pelco_KBD300A_Keyboard_Controller/4505-6502_7-31303919.html

They show up on ebay often and are in heavy use in CCTV.

Spec sheet here: ftp://www.pelco.com/ProductSpecs/c527.PDF