Tuesday, December 15, 2009

DIY Null Modem

I know serial ports are heading  towards obsolescence but I still need to use them occasionally. One piece of hardware often required for serial connections is a null modem. The following describes how I made a DB9 null modem.

I started off by purchasing two cheap plastic DB9 shells, a DB9 plug and a DB9 socket. DSC_0177
Next I screwed the shells together and hacksawed through the cable side of the screw holes on one shell and the plug side of the screw holes on the other shell. DSC_0178
After gluing the two cut down shells together I had a shell with a space for installing a DB9 connector in both ends.


From here it was a simple soldering job following the null modem pinouts from nullmodem.com and I had a compact DB9 null modem to put in my toolkit!




Transfer Drivers When Rebuilding a PC

A colleague of mine was recently rebuilding a pc for a remote site with no internet access. He had installed pretty much all the required software he could think of in the office before taking the new pc to site and we were talking through the job when he realised he would need a driver for an obscure serial PCI card.

Without any precise details of the card he was unable to find a driver to download before heading to site. And with no internet access on site he couldn’t rely on windows to find a driver online.

The card in question was still installed in the existing pc which could be run for 15 minutes or so without blue screening so I suggested that it may be possible to extract the driver for the card from the existing pc and transfer it to the new one. A quick Google showed up a couple of excellent driver backup utilities that will find all installed drivers on a pc and back them up to a folder.

I tested a few of these applications. My favourite is Driver Backup which is a tiny c# application that doesn’t require an install. Just beware that because this is a c# application the .net framework needs to be installed on the pc you are grabbing drivers from