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. 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 -----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.