For those that built their own cable what did you use for the serial port/RS232 connection. I searched for a non-complete cable but can't seem to find one. Would slicing an already complete cable in half and then just using the wiring I need work? If so which wires correspond to what pins?

 

Go to Radio Shack and get a 9-pin RS232 connector. They have two flavors, one with the pin already in the connector, and one that you have to put the pins in after you have soldered the wire to the pin. I like the ones that have to pins already installed. They seem to be more reliable. The black plastic part of the connector will have the pin numbers labeled. All of the schematics that I have seen show the pin numbers for the 9-pin RS232 connector some also show the pin numbers for a 25? Pin RS232 connector. I would check your schematic to be shore.

 

I went there last night and looked but the kid that was there was about as knowledgeable as me so we couldn't find them. I'll go back tonight and see what I can come up with. On a side note I did find those diodes so I'm good there

 

I just use a standard DB-9 to DB-25 serial cable, then you can build the board and components into a null modem adapter (they have DB-25 on both ends). Anyone know where to get the male ALDL plugs like those on the end of a handheld scanner??

 

A buddy built a box for me that does the RS232 conversion. I already had a cable from my Actron Scan tool that goes from the ALDL plug to DB15.... the box takes that DB15 and runs it through a MAX-232 chip into a DB9 connector. A standard serial cable then runs from the DB9 connector over to my laptop. The conversion box is powered by two pins of the laptop side, through diodes which protect my laptop; a 7805 +5 volt regulator makes sure the power off of the serial port is what my MAX-232 chip needs. The voltages on the car side of the box are 0V and +5V. The box turns these voltages into -10V and +10V for the laptop side. This is probably overkill for most of us as the cable that was posted on here with a transistor will work but this does take the data into a true RS232 voltage. Anyway I'll try to get some pictures and post a wiring diagram later.