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.