It might help to post the dmesg output from attaching the prolific
device.  I have some usb/serial converters, and some are revision 2
and work and some are revision 3 and do not (but I have not tried
lately).  The new chip is slightly different.  I tried to read a Linux
driver to figure out what to add but didn't succeed quickly and set it
aside.  But, if you can see responses to AT commands, I suspect this
isn't your problem.  Do the replies come promptly?



-- 
        Greg Troxel <gdt@ir.bbn.com>