If you for some reason are unable to configure your ZyXEL P650R or P650ME-series modem/router via Telnet, (T)FTP or HTTP, an option might be using the console port. To do this you need to connect your computers serial RS-232 port to the routers PS/2-style console port. You might have a hard time finding a cable that fits for your need, so why not make one?
Okay, so in the "computer end" you have a so-called DE-9-connector. It has 9 signal pins, of which you only need 5. In the "modem end" you have a MD-6-connector (mini-din, 6 pins) (PS/2, among other things, uses those), with 6 signal pins. Connecting them is a breeze. Personally I took the MD-6-connector out of a USB-to-PS/2 connector (you know, the ones you use for plugging USB mice into a PS/2 port) and connected it to one end of a null-modem cable that I didn't use.
So, the MD-6-connector has 6 pins. As mentioned before only 5 of them will be used. Here is the pin layout:
2 1
4 3
|
6 | 5
And here is the pin layout of a DE-9-connector, although it's probably not needed, as the wires are probably colored.
1 2 3 4 5 6 7 8 9
So, if you have everything you need, go on and solder. Here is an overview of how all pins should be connected:
| MD-6 pin | Signal | DE-9 pin | DE-9 wire color |
|---|---|---|---|
| 1 | DSR | 6 | Green |
| 2 | RXD | 2 | Brown |
| 3 | GND | 5 | Yellow |
| 5 | DTS | 4 | Orange |
| 6 | TXD | 3 | Red |
Leave the unused pins unconnected. You should now have a fully functional console cable. Plug it in and set your serial communication program to use VT100 emulation at 9600 baud, no parity, no flow control, 8 data bits and 1 stop bit. Press enter and you should get a password prompt. The default password is 1234.
Good luck!