Evan,

I keep an old ADM serial terminal around just so I can hook it inline to a serial device and watch the bytes being transferred. You can also hook up a PC if it's got 2 serial ports, read from one write to the other this will give you live realtime access to what's happening. I think there are some third party serial port eavesdropping programs out there, I'm not sure where to tell you to look. Try searching BlackBox I assume they have a website, they have all kinds of hardware for this type communication work.

>I would like to determine the format for the serial protocol between a Dallas SemiConductor Ibutton and a pc.
>
>We bought this technology from a healthcare company. The IButton allows us to transfer data from a piece of medical equipment into a a pc based database. The IButton is touched to a probe on the machine, data is tranferred to the button. The button is then touched to a probe on the pc and the data is loaded onto the pc.
>
>This works fine except that the healthcare company no longer supports the database and to top it off they contracted out the implementation of the iButton technology from a firm that is now out of business. The IButton technology is owned by Dallas semiconductor, but their documentation of the button is very low level (hardware) and not helpful to a software developer.
>
>I would like to somehow "sniff" the serial cable to determine how write a routine to transfer data from the button to a pc. Any ideas on how I could eavesdrop the serial cable?
>
>I don't think I am infringing on anyone's trade secrets. Comments appreciated.