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.