Willis, I would add the fact that the consumer quality USB to Serial adapters do not fully implement the RS-232 standard voltages for drivers swinging between +25 volts and -25 volts, and receivers that will accept a voltage of +3.5 volts or greater as a mark and those of -3.5 volts or less as a space. In addition, the slew rate may not be great enough to allow good conversion to real RS-232 levels.
BTW - this situation is nothing new - when the IBM PC was introduced, the serial port did not drive the negative level below -5 volts - that fact alone reduced the distance the IBM PC could drive RS-232 serial lines. The lack of adherence to standards (voltage levels, timings, etc.) has created a bunch of devices that "work", but while not to standards, do work in certain common instances - such is the fallout from consumer oriented USB to Serial adapters. As I have mentioned, there are commercial versions that "do it right", but they are quite "pricy" compared to the consumer variety that will work most of the time. There is a price to be paid for reliability and consistency. Make your choices and take whatever "licks" result from them. 73, Don W3FPR On 2/11/2012 6:25 PM, WILLIS COOKE wrote: > Ron, RS-232 serial interface has been defined for at least 25 years and its > functions are well known and stable so the radio software and hardware > producers can design to these specifications. The converters are designed to > emulate the portion of these functions that the designers feel are needed, > but do not conform to any IEEE standard so that other manufacturers can > depend on their function. RS-232 is coded and decoded by hardware, so it is > stable. USB converters are coded by some software and some hardware and are > decoded by the RS-232 receiver. The software portion is somewhat different > for the different operating systems. It takes a while after a new operating > system is implemented for the converter writers to get it right. FTDI and > Prolific are two companies who write software and sell chips for USB > converters. Lots of people buy chips from these two companies and mold them > into connector/cable assemblies and then retail them under > various brands. It is not real easy to find out which chips have been used > and often the end brand does not identify the chip used. Both of them work > OK with most printers, scanners and other serial connected computer stuff, > but it can be a different story with ham radio stuff where sometimes more is > demanded and RS-232 compliance is usually assumed. FTDI seems to do a better > job than Prolific, but you have to try the software/hardware combination > before you know. I had a lot of trouble when I bought a Win7 computer a > couple of years ago and endured some real rude comments from the computer > crowd when trying to figure out the combination. I bought a RS-232 card for > my computer and have not had trouble since. I suspect that the problems with > USB converters has been worked out in the two years so that things work > better now. My USB converter that I bought with my K3 in 2007 worked well > with the Elecraft software, but not with my loggers. I > understand that the older converters were Prolific and that Elecraft now > supplies FTDI, or at least something that will work. The cards work well > with desk top computers, but are not so easy with lap tops that have only > USB. The computer world is trying to get away from RS-232 in favor of USB, > but the ham radio community does not want to throw away perfectly good > hardware every four or five years like the computer world is geared to do. > Also, ham radio operators expect to know how everything works, computer > people not so much. > > Willis 'Cookie' Cooke > K5EWJ& Trustee N5BPS, USS Cavalla, USS Stewart > > > ________________________________ > From: roncasa<[email protected]> > To: [email protected] > Sent: Saturday, February 11, 2012 1:38 PM > Subject: Re: [Elecraft] serial to USB > > It really begs the question for some us who do not understand or are not > computer geeks: > > what IS the difference between FTDI and Prolific. > > We understand each one behaving (responding) differently with software > to radio control, and that some don't work at all, I do not understand > what makes one preferred over the other (such as elecraft serial/usb > adaptor cable) > Prolific also works with most stuff too. > For example, are they "platform" related? (micr0$oft) > Is this akin to "ordinary" DVD player as opposed to a "blue ray" player > that can play "both"?? > > 72 > Ron, wb1hga > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
