Can I make my own scanner for W140 and ODB-II?
 

I was wondering if it is possible to invent an own scanner for W140 and ODB-II just to get an rest the codes. I'm really so interested about it. If I can, from where shall i start? :)

Just make an interface for your laptop.

There are many out there, but now they are so cheap , $50] ,it is not worth making one.

Here is ISO
http://www.scantool.net/schematics.html

China is pumping them out now with ELM323 IC and USB port for cheap.
Here is Benz ISO one.

http://cgi.ebay.com/ebaymotors/ELM323-USB-ISO-OBD2-Scan-Tool-Interface-OBDII_W0QQcmdZViewItemQQcategoryZ43989QQihZ009QQitemZ190131981392QQrdZ1

Well you are right but I like to make one my own, can I? :)

<Well you are right but I like to make one my own, can I? >

I don't know, ..Can you??

I'm trying... But what I need are diagrams and software.

I'm going to guess "No".

If you weren't able to understand Arthur's answer regarding the simple interfaces you can buy, then I doubt you have what it takes to create your own and write the software to support it.

Or maybe I'm wrong, maybe I misunderstood your question and just what it was that you wanted to do, and what you truly lack is the understanding of how to put together a question on a Mercedes message board.

MV

Well I live in Kuwait. I wish if I have someone to trust to ship them for me, but as you know the Internet is full of scammers and I've been scammed once.

Then make your own
I gave you the schematic .. get the parts and solder it up.

Sure I need them. Thanks a lot. But where are they?

Open your eyes .
They are in the first post I did. Post #2.

..but you are asking for OBD2..and OBD2 is not analog, it is Digital.

now I got them, thank u so much :)

Your signature mentions a '92 W140...If that's the car you want to scan codes on, then you don't want OBDII, because that car is OBDI.

But if the car you want to design a scanner for is OBDII compliant, then I suggest setting your sights higher and create a device that will read codes from all systems on the car instead of just the drivetrain (that's what OBDII is limited to).