I still use a black box brand breakout box!! Indispensable to a field communications technician!
Ronnie W5SUM Sent from my iPhone > On Jul 9, 2018, at 11:04 AM, Dave Fugleberg <dave.w...@gmail.com> wrote: > > As a ‘field engineer ‘ for a global company in the 80s, I’d occasionally > find one of those RS232 breakout boxes tucked behind some production > system, jumpered to make the connection work, blinking away, because some > technician finally hit upon the magic combination and then left it in place > rather than building a proper cable. > I’ve seen lots of devices whose designers took great liberty with the RS232 > standard...a breakout box and some gender changers was indispensable in > working with a variety of serial devices. Sometimes even that plus a > healthy amount of experience wasn’t sufficient, as when marginal voltage > swings, extra long cables, and different ground potential at each end > conspired against you. > Lots of fun! >> On Mon, Jul 9, 2018 at 10:10 AM Cady, Fred <fc...@montana.edu> wrote: >> >> Thanks Don. It must have been interesting working all that out. I used >> to enjoy giving my students a history lesson explaining the control and >> handshaking signals in the RS232 connector from basic principles, starting >> with the Bell 103 modem. That didn't help explain the terminology and >> signal naming problem that Andy had. Manufacturers were terrible at keeping >> to the standard. And really, in isolation, it doesn't make sense that a >> signal named TxD would be a input and not an output. Documentation was >> scanty and so the scope, or my favorite test tool -- the RS232 Blinky Box >> -- had to be gotten out to tell what was what. >> >> The now used for other purposes signals are: >> DTR -- from the terminal to the modem to tell the modem the Data Terminal >> was ready. Now used for CW or PTT. >> >> DSR -- From the modem to the terminal to indicate the modem was ready >> (generally power on). >> >> The Bell 103 could send data only in one direction at a time so RTS and >> CTS were included to control the flow of the data. >> >> RTS -- Request to Send from the terminal to the modem to request the line. >> >> CTS -- Clear to send from the modem to the terminal to say the line was >> not busy and to go ahead with sending the data. >> >> RTS and CTS were also used to control the data flow from a fast device to >> a slow device. I think there were some kenwood radios that used this >> scheme. >> >> DCD -- Data Carrier Detected was used for the modem to tell the terminal >> that the carrier from the other data set was being generated (the phone >> line was working). >> >> RI -- Ring Indicator asserted by the modem when it heard a ringing signal >> at the other end of the telephone line. >> >> As I remember it. >> >> Cheers, >> Fred KE7X >> >> >> >> >> ________________________________ >> From: elecraft-boun...@mailman.qth.net <elecraft-boun...@mailman.qth.net> >> on behalf of Don Wilhelm <donw...@embarqmail.com> >> Sent: Sunday, July 8, 2018 10:04 PM >> To: elecraft@mailman.qth.net >> Subject: Re: [Elecraft] [KX3] RS232 xcvr control when serial ports are >> occupied >> >> The computer is the DTE device, and those devices designed to connect to >> the computer via the serial port are normally wired as DCE devices. >> >> The original thought when the IBM PC serial port was designed was that >> the PC would be used as a terminal connected to a modem, thus the >> decision was that the PC should be a DTE - and for the first several >> years the PC was used only as a terminal device. Yes, I was involved >> during those early days, but not as a part of that decision making >> process - I was involved with the IBM PC modems. My manager said I had >> "M" engraved on my forehead. >> >> Now we have the situation where the computer is the controller. It >> would be very confusing to change the wiring of the computer, so it >> remains as a DTE, and connecting devices (while not modems) are >> configured as a DCE, >> >> 73, >> Don W3FPR >> >>> On 7/8/2018 10:15 PM, Cady, Fred wrote: >>> Hi Andy, >>> >>> Don is correct. >>> >>> Here is a little blurb that might help. >>> >>> >> http://www.ke7x.com/home/miscellaneous-k3-information/unexpected-agc-behavior/rs232-interfaces-1 >>> >>> >>> ________________________________ >>> From: elecraft-boun...@mailman.qth.net <elecraft-boun...@mailman.qth.net> >> on behalf of Don Wilhelm <donw...@embarqmail.com> >>> Sent: Sunday, July 8, 2018 7:21 PM >>> To: ANDY DURBIN; elecraft@mailman.qth.net >>> Subject: Re: [Elecraft] [KX3] RS232 xcvr control when serial ports are >> occupied >>> >>> Andy, >>> >>> No TXD is TXD all the way through the path. Yes, the DTE TXD will have >>> the drivers, and the DCE will have receivers, but it is TXD from end to >>> end. RXD is the other way around because the DCE drives that line. >>> Trsnsmit and receive are named with respect to the DTE. >>> >>> 73, >>> Don W3FPR >>> >>>> On 7/8/2018 8:39 PM, ANDY DURBIN wrote: >>>> "TXD is really pin 3." >>>> >>>> >>>> One end's TXD is the other end's RXD. That's obvious to those who have >> used RS-233 for a while but if someone needs to ask then it may not be >> obvious. Find the TXD pin on the source and connect it the RXD pin on the >> destination. Sometimes it's easier to look with a scope than to try to >> understand the documentation. >>> ______________________________________________________________ >>> Elecraft mailing list >>> Home: http://mailman.qth.net/mailman/listinfo/elecraft >>> Help: http://mailman.qth.net/mmfaq.htm >>> Post: mailto:Elecraft@mailman.qth.net >>> >>> This list hosted by: http://www.qsl.net >>> Please help support this email list: http://www.qsl.net/donate.html >>> Message delivered to fc...@ke7x.com >>> ______________________________________________________________ >>> Elecraft mailing list >>> Home: http://mailman.qth.net/mailman/listinfo/elecraft >>> Help: http://mailman.qth.net/mmfaq.htm >>> Post: mailto:Elecraft@mailman.qth.net >>> >>> This list hosted by: http://www.qsl.net >>> Please help support this email list: http://www.qsl.net/donate.html >>> Message delivered to donw...@embarqmail.com >>> >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:Elecraft@mailman.qth.net >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to fc...@ke7x.com >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:Elecraft@mailman.qth.net >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to dave.w...@gmail.com >> > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to w5...@comcast.net ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
