Out of personal necessity I need to monitor some automobile sensor output
-- intermittent problem -- and datalog it. Have both a VB6 Oscilloscope software as well as some API RS232 port monitoring software.

Not being an electrical engineer - thought why not use the RS232 to do this.

However, a major concern is the voltages that any given sensor will put out in relationship to what the RS232 / computer can handle -- don't want to kill my computer.

So my questions are:

1) What pins of the RS232 port are the best for monitoring input?
For example if you have an oscilloscope (software) and it requires
two leads for input -- one should be ground and the other the signal
what RS232 pins should you use?

2) Can you hook up a sensor output directly to the RS232 port pins?
For example if the sensor puts out a voltage ranging from 0 to 5 volts, can this be hooked up directly to the RS232 port or will it kill it and the computer.

3) If NOT a direct hookup, how do you reduce the voltages (e.g resistor) to an acceptable level for the RS232 to handle?