Bob, For the sake of propriety please don't propagate myths. The RS- series of standards predate Radio Shack. The wiki at the following address has a good write-up about it:
http://en.wikipedia.org/wiki/RS-232 And, yes it is standardized. Although many have abused it. Bill....WB6BNQ Bob Camp wrote: > Hi > > In this case the RS relates to Radio Shack ...... > > Not a lot of standardization in the RS-232 world. Take a look at the slew > rate limiting requirements in the original document ... > > Bob > > On May 22, 2010, at 9:47 PM, Robert Darlington wrote: > > > Was there ever a standard? I always thought the "RS" stood for > > Recommended Standard, as in "you *should* do the following" as > > compared to "you shall do the following" I've seen inverted TTL talk > > to the RS232 port on laptops and I even sometimes use the max233's > > (+/- 10 volts instead of 12), but always use the full max232 with > > external charge pumps when it's a gadget that needs to work everytime > > with systems from multiple countries. > > > > -Bob > > > > On Sat, May 22, 2010 at 7:21 PM, Didier Juges <did...@cox.net> wrote: > >> Bruce, > >> > >> Thanks for the additional information. > >> > >> +/- 14V is quite unusually low in my experience. I typically use Maxim > >> parts such as the MAX220 series, which is specified at +/-25V for no > >> damage on the inputs (some parts in that series go to +/-30V). > >> > >> The bottom line is that as I pointed out earlier, there is no such thing > >> as an RS-232 standard any more. > >> > >> Didier > >> > >> ------------------------ Sent from my BlackBerry Wireless thingy while I > >> do other things... > >> > >> -----Original Message----- > >> From: Bruce Griffiths <bruce.griffi...@xtra.co.nz> > >> Date: Sun, 23 May 2010 10:39:21 > >> To: Discussion of precise time and frequency > >> measurement<time-nuts@febo.com> > >> Subject: Re: [time-nuts] Z3805 utility, Was: AW: (no subject) > >> > >> Didier Juges wrote: > >>> Bill, I think you got it backwards. +/- 12V is typical for RS-232, 0/+5V > >>> is > >>> for RS-422 and RS-485. > >>> > >>> No RS-232 receiver should be damaged with +/- 12V or even +/- 15V because > >>> that is their normal operating voltage. > >>> > >>> Also, RS-422 and RS-485 have something like 25V common mode tolerance (not > >>> sure what the actual spec is there,) so that the RS-422 and RS-485 > >>> receivers > >>> should not be damaged by 15V either. The RS-422 drivers are pretty low > >>> impedance, while the RS-232 drivers are current limited, so I don't think > >>> that connecting an RS-232 driver into an RS-422 driver will damage either. > >>> > >> Picking one RS485 receiver (ADM1485) at random the receiver absolute > >> maximum (no damage) input range is -14V to +14V. > >> The RS485 receiver operating common mode range is -7V to +12V. > >> RS422 receivers have an input operating range of -7V to +7V. > >> The no damage RS422 receiver input ratings may be higher. > >>> However, most recent (<10 years?) RS-232 receivers will work with a 0/+3V > >>> or > >>> 0/+5V input, conveniently having a threshold a few 10's or 100's of mV > >>> above > >>> ground, even though the original RS-232 spec required receivers that work > >>> with as low as +/- 3V, and drivers that deliver +/- 9V minimum. Many > >>> commercial systems use +/- 5V drivers for RS-232 (B&B Electronics sells a > >>> lot of converters with these voltages). This is a deliciously sloppy spec > >>> that nobody has met in the last 25 years probably, yet works most of the > >>> time. > >>> > >>> The one thing to avoid is to short an RS-422 (or RS-485) driver to ground, > >>> as that can actually cause damage, maybe not every time, but definitely > >>> not > >>> recommended. These have relatively high current output capability to drive > >>> long lines. > >>> > >>> Didier KO4BB > >>> > >>> > >>> > >> Bruce > >>> -----Original Message----- > >>> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On > >>> Behalf Of Bill Hawkins > >>> Sent: Saturday, May 22, 2010 3:09 PM > >>> To: 'Discussion of precise time and frequency measurement' > >>> Subject: Re: [time-nuts] Z3805 utility, Was: AW: (no subject) > >>> > >>> When all else fails, get out the voltmeter. > >>> > >>> Do you have power to the antenna? Is it the right voltage? All the way to > >>> the antenna? > >>> > >>> What volts are on pins 2 or 3 relative to pin 7 in the comm connector? > >>> > >>> If you see 12 volts, that's RS-422. You may have burned out your > >>> computer's > >>> serial port. > >>> > >>> If you see less than 5 volts, that's RS-232 and all should be well, unless > >>> you see zero volts. > >>> > >>> I may have the RS-xxx volts somewhat off because my memory isn't what it > >>> used to be. > >>> > >>> The guy you bought it from should be able to help with comm basics. > >>> > >>> Bill Hawkins > >>> > >>> > >>> -----Original Message----- > >>> From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On > >>> Behalf Of Robert Benward > >>> Sent: Saturday, May 22, 2010 2:08 PM > >>> To: Discussion of precise time and frequency measurement > >>> Subject: Re: [time-nuts] Z3805 utility, Was: AW: (no subject) > >>> > >>> Hi All, > >>> I hooked everything up and I still get nothing. I can't seem to establish > >>> communications with the Z3805. I tried a > >>> null modem as well, in case the cable (supplied) was wired with the wrong > >>> connector gender. I see a green blinking > >>> light inside, it he left rear corner of the box. Everything is warm, but > >>> nothing else. Any ideas? > >>> > >>> Bob > >>> > >>> > >>> > >>> > >>> _______________________________________________ > >>> time-nuts mailing list -- time-nuts@febo.com > >>> To unsubscribe, go to > >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > >>> and follow the instructions there. > >>> > >>> > >>> _______________________________________________ > >>> time-nuts mailing list -- time-nuts@febo.com > >>> To unsubscribe, go to > >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > >>> and follow the instructions there. > >>> > >>> > >> > >> > >> > >> _______________________________________________ > >> time-nuts mailing list -- time-nuts@febo.com > >> To unsubscribe, go to > >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > >> and follow the instructions there. > >> _______________________________________________ > >> time-nuts mailing list -- time-nuts@febo.com > >> To unsubscribe, go to > >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > >> and follow the instructions there. > >> > > > > _______________________________________________ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.