cnotesdip, basically you have to connect a signal/protocol converter.
You would need 4 types:
a) for Iso9141-2 and Iso14230 to convert 12Volt to say RS232C
b) for SAE J1850 VPW
c) for SAE J1850 PWM
d) for Can
For recording Iso you need some software that records serial channels complete with timing information and a signal converter. I use an old program called Comwatch (which is no longer sold) and a self-made signal converter. The signal converter converts 12Volt to TTL level and then from TTL to RS232C. You could use a KKL interface for this.
For recording SAE J1850 the Dearborn Group used to sell very good software/hardware.
For recording Can you have a broad selection of vendors. I use the Can Analyzer Tool from Actia.
Simulating ecu's from the PC is another matter.
The simplest are the Iso protocols if you are using a serial com-port. You need to convert the signal from RS232C to TTL and then from TTL to 12Volt. Again you could use a KKL-interface for this. The simulator you would have to write yourself.
For Can I use a programmable interface normally used for a scanner. This contains a CPU with a Can-interface that runs 8051-code. This needs software on the PC to download the code and change parameters PLUS the internal firmware for the 8051-based ecu and can-interface to generate the OBD2/EOBD protocol.