Serial communication over USB

[tsurikov]

Hello all,

I have a Linux system (2.4GHz, Asus P4PE MOBO, BIOS version 1002 running SuSE Professional 8.2) used in a lab environment, and want to use it to control several devices that communicate over a serial port. For the purposes of this question, what I need is the equivalent of communicating with a serial dumb terminal (e.g., VT340, and yes, I actually have one of those too).

I have successfully used Minicom (2.00.0) to do this communication over the two serial ports (/dev/ttyS0 and /dev/ttyS1) - no problem. I would like to be able to do this over the USB ports as well. I have a USB-to-RS232 converter (Magic Control Tech) which I know works. The trouble is, if I try to use Minicom to communicate using this converter over the USB port (/dev/ttyUSB0, for example), Minicom freezes almost immediately - no input/output, no keyboard response, etc. I don't know of any tools other than Minicom that provide terminal capabilities, but I'm also not sure where the problem is.

Does anyone have experience with this? Any suggestions are very welcome. Thanks much!
--Michael

 

[pansophic]

I have tried to get USB modems working, but it seems that not very many of the modem manufacturers are complying with the format that Linux is using. Take a look at:

http://www.linux-usb.org/USB-guide/book1.html

That is the best that I can say.

Sorry!


pansophic

 

[tsurikov]

Thank you, pansophic! That link was actually quite useful. I think the solution might be in there - but I'm not entirely sure because of my level of Linux expertise. Maybe I could ask for a bit more help from you..? The page that is most relevant to my problem is

http://www.linux-usb.org/USB-guide/x356.html,

which discusses USB-to-serial converters. It mentions something about "turning on USB Serial Converter Support" and the "generic serial driver" which must be loaded with an "insmod" command. First, how do I "turn on" that support? Second, where do I give the "insmod" command to load the driver? (I imagine it has to go in some config file...)

Thanks a lot!
--Michael

 

[pansophic]

The reference to turning on USB Serial Converter support would be a kernel option. If it isn't already compiled in to your kernel (I suspect that it is) then you would have to delve into custom kernel configurations.

You may need to have kernel sources installed if there isn't a USB-serial.o file on your system already.

If you haven't already, build an slocate database (slocate -u) and you can use 'slocate USB-serial.o' to find out where the file is if it is on your system. You can attempt to load that kernel driver using the insmod command. If your kernel doesn't have USB Serial Converter Support turned on, then the driver won't load.

You need to do insmod as root, and it is usually in the /sbin directory, but I'm not familiar enough with SuSE to be of any help.

Getting modules to load automatically is beyond my skill level. If you get it to load properly, I'd put up a new posting asking about loading kernel modules automatically. Someone out there will answer without a second thought.


pansophic