Help..on..connecting external modem directly to parallel port

stuboo · 10-17-2004, 07:10 PM

Hi,
I was wondering if anyone knows how to connect an external modem to a Linux machine with a male-male db25 cable (m-m parallel cable). The reason I ask is because I don’t have a db25-db9 cable (parallel to serial cable).

<<I would appreciate it if you would let me know if it is possible and if so how thanks stuboo>>

avarus · 10-17-2004, 07:24 PM

You can't plug a serial modem into a parallel port any more than you can shove a CD-ROM in the floppy drive. Fork out for a new cable.

stuboo · 10-17-2004, 07:38 PM

Well I was wondering if someone here knew how because I have seen people make and compile kernels for their machine to make it work. So my alternative question is does anyone know how to make and compile a kernel for debian to make it work?

michaelk · 10-17-2004, 09:34 PM

I suppose it would be possible but IMHO it isn't worth the effort.

BTW a DB25 connector does not mean parallel. There are DB25-DB25 cables wired as serial as well as for printers . I asume your DB25-DB25 is a printer cable.

stuboo · 10-18-2004, 09:34 AM

-------No it is a connector cable for connecting pc’s or for connecting scanners and other miscs.

<<<not printer(a printer is 25-32)>>>>>

stuboo · 10-18-2004, 05:06 PM

Anyone else have any ideas???

teckk · 10-18-2004, 08:11 PM

External Modems work from a UART serial port. The old serial ports were form DB25 then they changed to form DB9. Here is a link if you want to make cables.

http://www.blackdown.org/~hwb/hwb.html

http://www.hardwarebook.net/

teckk · 10-18-2004, 08:20 PM

Also is that 25 pin male on each end a laplink cable for connecting two machine together at the parallel ports? If so it is a crossover cable that will only work for that.

The old serial cables were 25 pin on each end. The cable ends would be female though as I recall.

stuboo · 10-19-2004, 04:15 PM

I dont think it is a laplink cable.

<<might be wrong but i dont think so>>

stuboo · 10-19-2004, 06:51 PM

<<<I checked it and it is not a laplink cable>>>

michaelk · 10-19-2004, 07:05 PM

Quote:

Originally posted by stuboo
-------No it is a connector cable for connecting pc’s or for connecting scanners and other miscs.

<<<not printer(a printer is 25-32)>>>>>

Not all printer cables have a centronics connector and besides its 36 pins not 32..

stuboo · 10-22-2004, 01:26 PM

I checked with a friend and he said something about having to recompile kernel 2.4.

eny one know how to do this?

michaelk · 10-22-2004, 05:55 PM

After thinking about this awhile you can not directly connect a RS-232 device into the parallel port because the voltages are not compatable. RS-232 is +/-12 VDC and the parallel port is 0-5 VDC. You might damage the parallel port if you connect the modem and turn it on.

Now, there are RS-232 to Parallel converters which then you could write a module but a converter is going to be more expensive then a cable. You can rewire your existing parallel cable to a serial cable easily enough.

http://www.linux.com/howtos/Text-Ter...HOWTO-22.shtml