Diagnostic port output signal/select monitor software?
 

Does anyone know if there is software downloadable or something to emulate what the select monitor reads and interprets from the diagnostic port in a classic or a legacy?

It must be something pretty basic as there are only two connections on the ecu for the select monitor signal. I'd like to be able to make up a serial cable to connect to the diagnostic port and study the output on my laptop but no idea what software (preferably free!!) might be able to do this and what connections I'd need to make at a serial port on the pc.

Any ideas would be great, cheers! :)