Alexinator

I have the 16 channel version of the StoreSafe Pro II. I notice on the back there is a little RS-232/DB9 port labeled Audio. I would love to get audio recording going. I only need one channel of audio. I've been searching for a while now, but cannot find anything that would help, either the accessory that would plug into that port or even a pin-out diagram so I could make my own.. Thanks for any help.