RJ45, RJ12, RJ14 cables, straight-through or crossover?

RJ45 network cables come in straight-through, and in crossover versions. Does straight-through in a patch cable mean that pin 1 in goes to pin 1 out?

What about everyday telephone cables? A flat cable, with wires going straight into the plug on each end. Physically, it looks like the very definition of straight-through. But does pin 1 in go to pin 1 out? NO!! Since the two plugs face in opposite directions, pin 1 goes to pin 4, and etc. Pin 1 to pin 1, would require a wire crossover or a 180-degree cable twist.

What about the straight-through RJ45 network cables? Yes! These DO have pin 1 in going to pin 1 out. And it's the crossover type that has pin 1 to pin 8, etc.

I thought about this at 3 AM, looked at a telephone cable, and changed the PCB layout for my beehive's five-sensor I2C jacks. But wait, are RJ11 RJ14 6P4C phone and RJ12 6P5C data cables different? Checking, Yes! An RJ11 voice cable can worked reversed, but an RJ12 data straight-through is pin 1 to pin 1. Some sellers of RJ11 RJ14 cables let you specify to get straight pin 1 to pin 1, or "reversed".

Sheesh, changing my PCB jack wiring back again.

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    - Win
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Winfield Hill
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Winfield Hill wrote in news: snipped-for-privacy@drn.newsguy.com:

Most ports have self negotiation Hdw at one end or the other or both and they auto handshake.

But to answer you query:

Googled "Gb ethernet wiring" and the very first picture has all your answers.

Reply to
DecadentLinuxUserNumeroUno

Most ethernet/RJ45 gadgets nowadays are agnostic to the crossover situation; they work either way.

In non-ethernet situations, like RS485 or such, I buy non-crossover RJ45 CATx cables, pin1 to pin1, just like most cable assemblies. I find that easier to understand on schematics.

I also find that I discover things at 3AM, or sometimes later in the shower.

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John Larkin         Highland Technology, Inc 

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John Larkin

Ethernet cross-overs swapped pairs.

Voice cables by default swapped polarity within the pair.

And 8-conductor telephone cables were a crap-shoot as to which way they were built, adding to the fun.

Telco cables cared about polarity so the (first generation) DTMF pads would work. I wonder if it even matters if an Ethernet cable has backwards polarity; not sure.

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Reply to
David Lesher

"Standards are a good thing. Every company should have one." I forgot who said that.

Before you invent a new wiring standard for I2C over RJ11 connectors, perhaps you might want to search for prior art[1].

Finding the right connector for I2C

Is there any definitive I2C pin-out guidance out there? Not looking for a "STANDARD"

6P6C I2C Connector Standard

I2C Bus Connectors & Cables

I2C - Community Recommended Pinout DRAFT 4th Feb 2015

There are probably more such "standards".

Drivel: In the distant past, I was marginally involved in trying to cram the 25 pin RS-232 wiring into an 8 pin RJ-45 connector while having the pin numbering reversible between DTE and DCE. Not my idea of fun. To make everyone happy, we had to use an (optional) 10 pin RJ-50 connector.

[1] If it does something disgusting when reversed, like destroy the bus transceivers, you can blame whomever originally contrived the wiring standard.
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Jeff Liebermann     jeffl@cruzio.com 
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Jeff Liebermann

(...) Are you doing something like this?

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Jeff Liebermann     jeffl@cruzio.com 
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Jeff Liebermann

Jeff Liebermann wrote in news: snipped-for-privacy@4ax.com:

Probably Carnegie, Morgan, or Rockefeller... Naaah!

Sounds more like something Twain would have said.

Reply to
DecadentLinuxUserNumeroUno

Jeff Liebermann wrote in news: snipped-for-privacy@4ax.com:

That is pretty cool.

Reply to
DecadentLinuxUserNumeroUno

Yes, all that and much much more. 60 sensors so far, and now adding 12 more, including gas sensors. E.g., we count every single bee trip in/out of hive, see up to 170,000 trips (not under 10,000). Including the back door. Two microphone sensor channels. Also getting sugar-water level. LoRa real-time reporting. As a scientific research tool, have learned a lot, I hope, but not yet sure of value to experienced beehive operators. Had 6 systems out last season, will deploy 15 more this season.

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    - Win
Reply to
Winfield Hill

Yep. Some of the details on how bee hive monitor is used are interesting. I didn't know that the life of a bee hive is so complicated: Hive Management

Instead of one connector for each PCB designers idea for creative I2C wiring and pinout, he simply crimps the cable to match his wiring standard. See photos of PCB at: and wiring at: I've been through the DHT22 humidity sensor color coding mess with my various weather stations.

Methinks he made a mistake with the TSL2591 Lux Sensor wiring, which shows that the cable is wired for "standard" telco crossover wiring, which might a problem since the 3.3v and ground are on opposite ends of the RJ14 connector and reversing them might become a smoke test. My rule of thumb is that if it's used for telco, then a "rollover" or mirror image connector wiring should be used. For everything else, I wire it pin 1 to pin 1.

Oops. I don't think the author thought this out very well: Consider cutting a 10 or 12' cord in half for two sensors, crimping will be unnecessary. If he uses "standard" telco flat cable, cutting it in half will result in two different (mirrored) RJ11 wiring configurations for each half. I suspect he wrote that before actually trying it.

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Jeff Liebermann     jeffl@cruzio.com 
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Jeff Liebermann

See DropBox for my six-channel sensor board:

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RIS-788_BME280+Si1145+LED.JPG shows daughter PCB with T + RH + mBar pressure, plus three light channels, plus a bright LED heartbeat. That was last year's I2C sensor board; this year's new I2C board adds five ICs, with 12 channels, located in the middle of the hive, see TH-stick_sensors-only_3D.PNG

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    - Win
Reply to
Winfield Hill

It was much more recent. As I vaguely recall, it was said by a well known computah industry luminary during some long forgotten patent battle the 1990's. However, Google couldn't find it, so the quote must not exist.

2nd best: The good thing about standards is that there are so many to choose from. (Andrew S. Tanenbaum)

I would guess some flavor of I2C wiring and color coding will eventually become the de facto standard, where it doesn't need to be the superior solution, it just needs to mostly work. Meanwhile, the success of external I2C sensors and wiring will depend mostly on how the technology is misused, abused, and priced.

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Jeff Liebermann     jeffl@cruzio.com 
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Jeff Liebermann

Jeff Liebermann wrote in news: snipped-for-privacy@4ax.com:

With so many units involved, buying a set of 500+ connectors and

500+ sockets for PCB mounting and using a modern, micro-sized form factor would seem to be far better. Much higher integrity connections and one can perform any pair twisting or coax run or any other schema for the interlinks. Even a set of sata pairs (plug and socket) would seem better as they can be stacked on a PCB layout one right next to the next one. Ten sata connector sockets would fit on an interface pcb in a couple square inches, whereas those old phone interlink jacks and plugs are simply far to big for such a huge sensor unit count.

Very similar to the old audio interconnect cables on the first CD players for PC installation. They are like 3 or 4 wire inline miniature connector heads. They were white and they had god retention in their deisgn.

Google images or just google

jst sh jumper

Reply to
DecadentLinuxUserNumeroUno

Winfield Hill wrote in news: snipped-for-privacy@drn.newsguy.com:

H

Outdoor?

Te connectivity.

"SLIMSEAL"

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connectors/Xpmyza.html

Reply to
DecadentLinuxUserNumeroUno

Last year's I2C board is inside the monitor box, exposed to the outside. This year's additional I2C sensor board is in the middle of the hive.

Very interesting, I hadn't found that one. But, what's with only up to 3 positions available?

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    - Win
Reply to
Winfield Hill

Winfield Hill wrote in news: snipped-for-privacy@drn.newsguy.com:

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connectors/Xpmyza.

automotive target 'demographic'. I didn't notice.

OK so somebody needs to tell them we need more positions.

I looked. Their ip67 unit with 8 positions is a CAT7A unit for long haul and is a couple hundred each. Wow.

Reply to
DecadentLinuxUserNumeroUno

On a sunny day (12 May 2019 18:09:31 -0700) it happened Winfield Hill wrote in :

I wonder if this sort of technology

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without the killing green laser part, can be used to track individual Bs. Each B having its own wing flapping pattern, some AI learning software.. Maybe ask that Microsoft inventer?

Reply to
Jan Panteltje

Jan Panteltje wrote in news:qbb29q$rbl$ snipped-for-privacy@dont-email.me:

Their own wing flapping pattern?

No, they are all the same and their wing flapping 'patterns' are too.

The software counts the actual bees. It does not discriminated down to wing motion... And never will.

Reply to
DecadentLinuxUserNumeroUno

We count every bee trip going in or out of the hive. This is a little different from measuring bee flights. Standing in front of the hive, watching for 15 minutes, say in the morning, virtually all of the IN/OUT trips are associated with a flight. The bees seem to know exactly what they're doing, and concentrate on that.

And yet we count up to 20x as many trips as they measure flights. OK, it is true that in the late afternoon, I've observed a lot of IN/OUT activity not associated with bee flights. They seem unsure at that point in time, and may even make a wall of bees on the front of the hive. But this time-frame is not when we get most trips counted. It appears that their camera and software must miss seeing a lot of flights.

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 Thanks, 
    - Win
Reply to
Winfield Hill

Winfield Hill wrote in news: snipped-for-privacy@drn.newsguy.com:

Paralax error goes up during large exodus/ingress periods.

I used to make pharma tablet counters and they had 16 channels for the pills to fall through and yet would still fail if two went through together past the optical sensor in a channel.

Most pharmacies I see these days have gone back to hand counting. much cheaper than the expensive tablet counters.

Reduce camera resolution and increase frame rate. Somewhere there is a happy medium where optimal counting is the result.

Reply to
DecadentLinuxUserNumeroUno

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