Null-modem cable driver

Windows NT, 2000 and XP have a driver for null-modem cable, it's called "Communications cable between two computers". The maximum speed is 115200 bps. On some machines serial ports can handle higher speeds. There are also several USB-to-Com adapters that can work on speeds faster than 115 Kbps. Iogear GUC232A works for sure. Here the inf file for null modem cable with max speed 230400 bps.

Installation

Install your USB dongle driver first. Than right click on the nullm230.inf, select "Install". Than open "Phone and Modem options" in the Control Panel. Open "Modems" tab, click "Add", check "Don't detect...", "click "Next", select "high-speed cable" on the left and "230.4Kbps null-modem cable" on the right. Win XP will tell you that driver isn't signed, but that's ok. Click "Next", select port, Win XP will warn you that "... has not passed Windows Logo testing to verify ... bla-bla ...", click "Continue Anyway". You are good to go.

PPP connection to Windows desktop

On Windows machine open "Network Connections" in the Control Panel. Run "New Connection Wizard". Select "Accept incoming connections" on Win 2000 ("Set up an advanced connection", than "Accept incoming connections" on XP), select your device ("230.4Kbps null-modem cable"), select "Do not allow VPN connections", select user, can be any user, make sure TCP/IP protocol is selected, click "Finish". Now you have new connection ("Incoming connections") in the Network Connection folder. Open "Properties", open "Users" tab and make sure that checkbox "Always allow directly connected devices such as palmtops to connect without providing a password" is checked. Now Windows machine is ready.

On Psion make sure you have ppp package installed. Copy provider script to /etc/ppp/peers/winras and chatscript to /etc/chatscripts/winraschat. If you connect to Windows 2000 or NT you need to put a valid DNS server to /etc/resolv.conf and comment out the last line in /etc/ppp/peers/winras. "pon winras" to initiate PPP connection.

If you want to make telnet or ssh connections from your desktop to Psion, make sure that /etc/inetd.conf has the proper stuff and inetd is started.

-- AlexOrlov - 18 Jul 2005
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