I have run 9600 baud data over 200-300' many times and the statement that a RS232 driver is being used (presumably a Max-232 which is pretty popular & the one we use) then it will drive a couple of hundred feet of wire BUT there is one catch we learned early-on. That is to double up the wires to lower the resistance and since CAT5 has 4 pairs you only need TX, RX and Gnd of course; so if you use one pair for each line that even leaves one pair left over and we have seen up to 300' of line driven by this trick.
Naturally it is something of a pain to put 2 wires in a crimp-on pin to get them into a DB9 or whatever connector you are using...that is a given, but the end does justify the means sometimes. I sure wouldn't try it at 19,200 or above of course; but for 9600 or lower (perhaps switch to 4800 if you can do it...) we have a 100% success rate. Perhaps this will help... Robert L. (Bob) Burchett Certified Communications Engineer Enterprise Electronics Contractors License 522372 22826 Mariposa Ave. Torrance CA 90502 310.534.4456 [email protected] -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of [email protected] Sent: Wednesday, July 02, 2014 3:09 PM To: [email protected] Subject: time-nuts Digest, Vol 120, Issue 7 Send time-nuts mailing list submissions to [email protected] To subscribe or unsubscribe via the World Wide Web, visit https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts or, via email, send a message with subject or body 'help' to [email protected] You can reach the person managing the list at [email protected] When replying, please edit your Subject line so it is more specific than "Re: Contents of time-nuts digest..." Today's Topics: 1. Re: FASTRAX GPS (Chris Albertson) 2. Re: FASTRAX GPS (Alexander Pummer) 3. Re: FASTRAX GPS (Chris Albertson) 4. RE : Re: FASTRAX GPS (Jean-Louis Oneto) 5. Re: FASTRAX GPS (jim s) 6. Re: RE : Re: FASTRAX GPS (jim s) 7. Re: FASTRAX GPS (jim s) 8. Re: RE : Re: FASTRAX GPS (Hal Murray) ---------------------------------------------------------------------- Message: 1 Date: Wed, 2 Jul 2014 12:36:06 -0700 From: Chris Albertson <[email protected]> To: Discussion of precise time and frequency measurement <[email protected]> Subject: Re: [time-nuts] FASTRAX GPS Message-ID: <cabbxvhskdyqnrpi8esfnw6odafrh3+c1lmj8r+nlgefsw_l...@mail.gmail.com> Content-Type: text/plain; charset=UTF-8 I tried using it as pairs but you really can't. You have Tx, Rx and the PPS all sharing one ground return and the ground is not even a current return because each end is connected tho the building ground system. So you can TRY to use pairs like I did but it remains unbalanced. Yes you can make it work by using balanced pairs but then it is no longer RS232 and need driver/receiver chips and level conversion at each end. Balanced lines work very well. The problem is that the RS232 receiver looks only at the voltage on one of the wires in the pair relative to ground and not the difference between the wires in the pair. On Wed, Jul 2, 2014 at 10:45 AM, Hal Murray <[email protected]> wrote: > > [email protected] said: >> I tried using a long serial cable. Just because I had some 100 feet >> of >> cat-5 wire already installed. It did not work reliably I was using a >> MAX232 chip as a driver. > > Were you using it as 8 separate wires or 4 pairs? > > I'd expect RS-232 to work over 100 ft of Cat-5 if you used half of > each pair as a ground. (That's at 9600 baud.) > > -- > These are my opinions. I hate spam. > > > > _______________________________________________ > time-nuts mailing list -- [email protected] To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. -- Chris Albertson Redondo Beach, California ------------------------------ Message: 2 Date: Wed, 02 Jul 2014 13:00:53 -0700 From: Alexander Pummer <[email protected]> To: [email protected], Discussion of precise time and frequency measurement <[email protected]> Subject: Re: [time-nuts] FASTRAX GPS Message-ID: <[email protected]> Content-Type: text/plain; charset=ISO-8859-1; format=flowed the trick of every data line is; it has to me matched to it's impedance, at least at the receiving end, other way it is ringing. Every pair of conductor becomes transmission line as soon it's length exceeds " the length of the rise time" of the signal which is traveling on it. 73 Alex On 7/2/2014 11:46 AM, Wojciech Owczarek wrote: > My 2c - RS232 is extensively used in data centres over cat5 with network kit for out of band management via serial consoles, usually 9600 baud. > > I've done this many times via (multiple) patching panels/frames easily over 100ft, ribbon/rollover then cat6 but also cat5. This kit tends to be reliable and usually well grounded though. Well, and "compliant". > > > Wojciech Owczarek > _______________________________________________ > time-nuts mailing list -- [email protected] To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ------------------------------ Message: 3 Date: Wed, 2 Jul 2014 13:25:45 -0700 From: Chris Albertson <[email protected]> To: Discussion of precise time and frequency measurement <[email protected]> Subject: Re: [time-nuts] FASTRAX GPS Message-ID: <cabbxvhv5y5jm3ghe1l5x2vc7vngbjcq3x7wm1ettpf5rc+1...@mail.gmail.com> Content-Type: text/plain; charset=UTF-8 On Wed, Jul 2, 2014 at 1:00 PM, Alexander Pummer <[email protected]> wrote: >> I've done this many times via (multiple) patching panels/frames >> easily over 100ft, ribbon/rollover then cat6 but also cat5. This kit >> tends to be reliable... Does this include the PPS signal on the DTR pin? I think this is part of the problem with a long serial cable and GPS. The pulse is sometimes VERY short. Again, yes you could fix this by introducing circuits at each end. And what were you sending? Typically in an IT environment you'd be using serial for the admin ports of routers and the like. Basically you run terminal emulators and it does not matter if one in 1,000 characters is corrupted. The data is not checksummed and you'd rarely notice an error. The Binary TSIP data from a Thunderbolt is checksummed and runs 24x7 so you notice every error. But really, the main problem was the PPS. -- Chris Albertson Redondo Beach, California ------------------------------ Message: 4 Date: Wed, 02 Jul 2014 22:29:14 +0200 From: Jean-Louis Oneto <[email protected]> To: Discussion of precise time and frequency measurement <[email protected]> Subject: [time-nuts] RE : Re: FASTRAX GPS Message-ID: <[email protected]> Content-Type: text/plain; charset=utf-8 Hello, AFAIK, the differential variant of RS-232 is RS-485. I'm not sure about the levels.? Best regards,? Jean-Louis Oneto Envoy? depuis un mobile Samsung? -------- Message d'origine -------- De : Chris Albertson <[email protected]> Date :02/07/2014 21:36 (GMT+01:00) A : Discussion of precise time and frequency measurement <[email protected]> Objet : Re: [time-nuts] FASTRAX GPS I tried using it as pairs but you really can't.? You have Tx, Rx and the PPS all sharing one ground return and the ground is not even a current return because each end is connected tho the building ground system.?? So you can TRY to use pairs like I did but it remains unbalanced. Yes you can make it work by using balanced pairs but then it is no longer RS232 and need driver/receiver chips and level conversion at each end.? Balanced lines work very well. The problem is that the RS232 receiver looks only at the voltage on one of the wires in the pair relative to ground and not the difference between the wires in the pair. On Wed, Jul 2, 2014 at 10:45 AM, Hal Murray <[email protected]> wrote: > > [email protected] said: >> I tried using a long serial cable.? Just because I had some 100 feet >> of >> cat-5 wire already installed.? It did not work reliably I was using a >> MAX232 chip as a driver. > > Were you using it as 8 separate wires or 4 pairs? > > I'd expect RS-232 to work over 100 ft of Cat-5 if you used half of > each pair as a ground.? (That's at 9600 baud.) > > -- > These are my opinions.? I hate spam. > > > > _______________________________________________ > time-nuts mailing list -- [email protected] To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. -- Chris Albertson Redondo Beach, California _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ------------------------------ Message: 5 Date: Tue, 01 Jul 2014 22:13:33 -0700 From: jim s <[email protected]> To: Discussion of precise time and frequency measurement <[email protected]> Subject: Re: [time-nuts] FASTRAX GPS Message-ID: <[email protected]> Content-Type: text/plain; charset=ISO-8859-1; format=flowed On 7/1/2014 8:27 PM, Hal Murray wrote: > It's often easier to use a long serial cable rather than a long antenna cable. Excellent suggestion. I will look at that as an alternative. I wanted to keep the FASTRAX and the unit is mated to near my systems, but for other GPS setups with other chips that would be good. Thanks Jim ------------------------------ Message: 6 Date: Wed, 02 Jul 2014 14:49:17 -0700 From: jim s <[email protected]> To: Discussion of precise time and frequency measurement <[email protected]> Subject: Re: [time-nuts] RE : Re: FASTRAX GPS Message-ID: <[email protected]> Content-Type: text/plain; charset=UTF-8; format=flowed On 7/2/2014 1:29 PM, Jean-Louis Oneto wrote: > Hello, > AFAIK, the differential variant of RS-232 is RS-485. I'm not sure about the levels. > Best regards, > > > Jean-Louis Oneto You have to control the direction of RS485. You don't have to with RS232. One of the problems with support of RS485 in Linux OS kernels is that the kernel can't respond to the turning of the line quickly enough in real time. I had an application with 115k requirement, and it had to turn the line within 1/10 of a bit time. Pretty quick for a kernel. It is differential, and it does send data, but is a different beast in many ways. I would have liked to have had an external processor to handle the RS485, and some chips do that, but we had the engineer just attach two serial ports on an Arm SOC to the usual serial uarts, and it was fun figuring out how to make it work. BTW this was for communicating with an airframe, and the avionics dictated the rate we had to turn the lines. It was for passenger signals, etc., so was simple, but you basically ran all the cabin lighting and attendant signalling thru one line for the entire aircraft. ------------------------------ Message: 7 Date: Wed, 02 Jul 2014 14:52:47 -0700 From: jim s <[email protected]> To: Discussion of precise time and frequency measurement <[email protected]> Subject: Re: [time-nuts] FASTRAX GPS Message-ID: <[email protected]> Content-Type: text/plain; charset=ISO-8859-1; format=flowed I noticed on Toms info page, (very good along with the two emails for info) that there is no connection called out for the antenna power. There are two power in pins, Primary and Backup power. Since I'm going to use an active antenna, can I send the 5 v up the antenna power, or will the Primary power propagate and power the antenna? The Antenna power is pin 1. thanks Jim On 6/20/2014 8:31 AM, Tom Van Baak wrote: > Hi Ernie, Jason, (also Hal, Chris), > > I'm able to get NMEA and 1PPS out of the Fastrax/iTrax130 board now. > > Before I sink any more time into this project, have any of you made 1PPS measurements? > > Compared to ublox, using the same antenna, these units take tens of minutes or even hours to lock. And they have a bad habit of being close to UTC for a few hours but then gradually wandering off by tens or hundreds of microseconds. > > A power cycle puts them back on track (aligned with UTC), so it would seem to be a firmware issue rather than antenna or reception. A similar thing happens on three different boards I have evaluated over the past two weeks. > > Now, when they are working right, the 1PPS has an RMS deviation of around 20 ns, which I've come to expect as typical for cheap GPS/1PPS receivers these days. But the long lock times and unexplained 1PPS drift make them unreliable for GPSDO or serious timing work, even at $12 each. > > It might be me, so I'm asking if you've seen anything similar. The binary command set looks tempting, but I usually don't play with that until the unit can be trusted to give reliable NMEA and 1PPS output. > > Unfinished page: http://leapsecond.com/pages/itrax/ > > /tvb > > ----- Original Message ----- > From: "Ernie Peres" <[email protected]> > To: <[email protected]> > Sent: Wednesday, June 11, 2014 4:11 AM > Subject: Re: [time-nuts] FASTRAX GPS > > >> Hi Jason, >> >> >> I figured out a different pin assignments.... >> >> hold the PCB so that the SMA antenna connector is looking to right and under the PCB. >> >> open- 1 2- Ant power presently connected to pin nbr 4 >> TX- 3 4- Main power +3 volt >> RX- 5 6- 1PPS >> open- 7 8- Grnd power -3 Volt >> >> the unit takes about 60mA @ 3,0 volt and comes-up in NMEA mode.. 9600 Baud. >> I use the FASTRAX_WORKBENCH_522 software. >> I wonder if anybody has other pin arrangement/connection. The 2 open pins is UNK and also not sure if pin nbr 4 is the main power or perhaps the pin nbr 2......?? >> >> Rgds Ernie. >> > > _______________________________________________ > time-nuts mailing list -- [email protected] To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > ------------------------------ Message: 8 Date: Wed, 02 Jul 2014 15:08:24 -0700 From: Hal Murray <[email protected]> To: Discussion of precise time and frequency measurement <[email protected]> Cc: [email protected] Subject: Re: [time-nuts] RE : Re: FASTRAX GPS Message-ID: <[email protected]> Content-Type: text/plain; charset=iso-8859-1 [email protected] said: > AFAIK, the differential variant of RS-232 is RS-485. I'm not sure > about the levels.? RS-422 is the basic version: http://en.wikipedia.org/wiki/RS-422 RS-485 is the multipoint version. Interesting comment from http://en.wikipedia.org/wiki/EIA-485 The EIA once labeled all its standards with the prefix "RS" (Recommended Standard), but the EIA-TIA officially replaced "RS" with "EIA/TIA" to help identify the origin of its standards.[1] The EIA has officially disbanded and the standard is now maintained by the TIA. The RS-485 standard is superseded by TIA-485, but often engineers and applications guides continue to use the RS designation. -- These are my opinions. I hate spam. ------------------------------ _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts End of time-nuts Digest, Vol 120, Issue 7 ***************************************** _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
