On Monday 08 December 2003 03:59pm, Alessio Sangalli wrote: > Hi, I wrote an email directly to "greg at kroah.com" because he's the > author of the pl2303 driver but I think I could have some help here too > about an issue with the pl2303 driver. > > if I connect a usb-serial adapter to my laptop, and I connect to this > adapter an external serial modem, everything's perfect. But, if I > connect another device, for example a telescope, (which happens to have > only 3 lines connected, TX, RX and GND) I can't send or receive > anything. The same hardware works well in windows and I can access the > telescope using minicom on a desktop computer with a real serial port. > > Do you perhaps think that, the pl2303 doesn't work well with devices > that implement a 3-wire only communication? Is there somothing to do? > > I used linux-2.6.0-test11-bk5 and linux-2.4.23 in my tests.
This sounds (almost) exactly like the problem I had with the Belkin F5U109 USB/RS-232 adapter. In short, output data gets held up in the USB/RS-232 adapter for RS-232 devices which don't assert the 'CTS' signal. An external modem worked just fine (reads and writes). However, a Garmin GPS receiver (wired like your telescope) would not accept any commands (writes) even though the reads worked just fine. I was able to fix it by running "USB Snoopy" (aka SniffUSB) on the Windows driver and realizing that a couple of extra (undocumented) USB commands were being sent to the USB/RS-232 adapter whenever the baud rate was set. I have a pending patch for 2.4 and 2.6 that fixes this nicely by mimicking the Windows driver's behavior. For much more detail, scan this list's archives for my email titled "Patch For Problem Writing Data Via USB/RS-232 Adapters Using 'mct_u232' Module", dated 05 Nov 2003: http://sourceforge.net/mailarchive/forum.php?forum=linux-usb-devel I don't own a pl2303-based adapter and have no idea if this is the same issue. My problem only happened when _writing_ data to the RS-232 device, not when _reading_ from it, but it sure sounds similar to me. Good luck and let me know if you need more information that's not in the list archives. Bill Marr ------------------------------------------------------- This SF.net email is sponsored by: IBM Linux Tutorials. Become an expert in LINUX or just sharpen your skills. Sign up for IBM's Free Linux Tutorials. Learn everything from the bash shell to sys admin. Click now! http://ads.osdn.com/?ad_id=1278&alloc_id=3371&op=click _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
