Yes indeed.
USB drivers are critical for Linux.
Renesas and FTDI are the cream of the crop as far as kernel drivers go for Linux. Prolific works but is at the bottom of the list. Many others won't work at all.
Prolific chipsets, and this is true of Windows or Linux, do not support the full set of baud rates. Renesas and FTDI do, plus the drivers on either OS are very good. Prolific drivers are not.
It's hard to know what you have for an internal USB chipset when buying adapter cables, but any good cable manufacturer will generally state that they are using a Renesas or FTDI chipset because they want to brag it up that you are not buying sub-standard or unusable hardware but getting the best chipset. If it does not say what chipset it is, walk away and do not buy it.
I went through this time and again before I retired on the corporate level and it was always a nightmare for the end user if they did not have a Renesas or FTDI chipset based USB to serial apter cable.
I expect someone will write in and tell us they did not have any trouble, well, that I am happy for. But it is not the norm on these sub-standard USB adapter cables. This is a case where you get the best one and be done with it and they just work, or you cheap off and they don't or don't work right, or the drivers keep breaking. Prolific chipsets actually did have decent (acceptable) drivers back in the Windows 7 days, but not since then and never really for Linux. Some of these adapter chipsets do not even deliver the RS-232 standard voltages of +12 and - 12 volts, but rather supply +5 and 0 volts. Not all devices (many in fact) will operate with this deficiency. The idea is that the positive to negative swing in voltage that the RS-232 standard defines allows for a great deal of noise immunity, and many USB transceivers will ignore the (supposed to be a dead) band around zero volts as they should and up to at least a few volts for a logic high (there is also hysteresis so that noise will not false the data and this needs correct voltages to operate correctly).
Some applications are pretty forgiving of a poor USB to serial adapter chipset but not radio and timing related things like we are doing.
Rick Kunath, K9AO
