6 ms·
Also, it's 8P8C, not RJ45, and sometimes it's more important to use the term from a standard body, but usually it's more important to use the term everyone know
by dlcarrier 1y ago
Also, it's 8P8C, not RJ45, and sometimes it's more important to use the term from a standard body, but usually it's more important to use the term everyone knows. When documenting, I recommend saying something like this:
J3 is an 8P8C jack (commonly RJ45) for IEEE P802.3bz 2.5GBASE-T communications, backward compatible with Gigabit and Fast Ethernet
- bobmcnamara 1y agoMost 8P8C other connectors are incompatible with RJ45. Why wouldn't you say RJ45?
- bigbuppo 1y agoRJ45 is a specific AT&T USOC order code to slap a normal 8P8C jack on someone's wall to provide something like multi-line analog telephone service.
- Sammi 1y agoI used to do phone support for a phone company / isp and I have no idea what you just wrote.
- SV_BubbleTime 1y agoHe said RJ45 is an AT&T part/reference number. Just like RJ11 which is your small phone plug that had 6pins, more rare.
- arghwhat 1y agoNit: RJ11 has two contacts. RJ11, RJ14 and RJ25 all used the same 6P housing though, making them 6P2C, 6P4C and 6P6C connectors, respectively. Things sold as RJ11 is often 6P4C, making for another error. The rule of thumb is that anything referred to as RJ-something is likely wrong.
- craftkiller 1y agoTo be fair, 5 out of the 6 phone support agents I talked to at Optimum (an ISP) did not know what IPv6 is, so saying you used to do phone support for an ISP isn't really saying much.
- gjvc 1y agoyou tell him!
- SAI_Peregrinus 1y agoRJ45 is a connector with a key notch sticking out and a "programming" resistor joining two of the pins. It won't work for Ethernet at all, the plug side can't even fit in the 8P8C socket Ethernet uses. If you grind off the key it'll still not work, because of the embedded resistor. Also the pinout is totally wrong, so even if you didn't have the resistor it wouldn't work. None of the RJ connectors have the correct pinout for Ethernet.
- arghwhat 1y agoRJ45 is a mechanically (slightly) different connector, but indeed all RJ specs were for phone lines, with RJ45 focused on several lines for high speed modem connections. The regular ethernet 8P8C connector was defined by both an ANSI and ISO spec, neither of which gave the connector an actual name as it covers modular connector designs. :/
- LukeShu 1y agoRJ45 is a keyed 8-position jack, not a normal 8-position jack. ("Keyed" means that there's a notch in the side making it a different shape; you would not be able to fit an "Ethernet" connector into it.) Closer is RJ38X, which is a series 8-position jack, not a normal 8-position jack. ("Series" means that the jack shorts pint 1 to pin 4 and pin 5 to pin 8 when there's not a cable plugged in to it; you would be able to fit an "Ethernet" connector into it, but even so it's probably not what you want.) AFAICT (skimming 47 CFR part 68, and the historical AT&T documents that became 47 CFR part 68), there is no RJ-number for a normal 8-position jack.
- pests 1y ago> you would not be able to fit an "Ethernet" connector into it Because of the size being different? Surely a keyed female plug will take a male connector with or without the key. Or did you mean you couldn't fit a RK45 connector into a Ethernet plug because then the key would interfere?
- wsh 1y agoRJ45S and RJ45M are ordering codes for so-called “registered jack” configurations for terminal connections to the U.S. telephone network. These codes were defined until 2000 in the FCC Rules (47 CFR § 68.502(e)) and later in the TIA/EIA-IS-968 standard, and they refer to single and multiple arrangements of two wires and a programming resistor on a miniature eight-position keyed jack. https://www.govinfo.gov/content/pkg/CFR-2000-title47-vol3/pdf/CFR-2000-title47-vol3-part68.pdf#page=140 https://www.govinfo.gov/content/pkg/CFR-2000-title47-vol3/pd... Unfortunately, the “RJ45” part of these codes has become a metonym for the unkeyed version of the miniature eight-position jack and plug, now widely used for Ethernet and other purposes, but strictly speaking, RJ45 refers to a different connector with totally incompatible wiring.
- LukeShu 1y agoSpecifically, what is colloquially an "RJ45" or "Ethernet" connector is an 8P8C "Bell System Miniature Plug/Jack" (AT&T's original name; it is a smaller version of the older Bell System connectors) / "miniature plug/jack" (FCC genericization of the name by removing "Bell System", even though the word "miniature" is no longer meaningful without context) / "modular jack" (ANSI/IEC genericization). That is what is meant when just "8P8C" is said. Pedantically speaking, RJ45 (as first defined by AT&T internally[1], and later by the FCC's 47 CFR part 68) is not that. The RJ45 socket is a keyed 8P8C modular jack, not a regular 8P8C modular jack. Here is a photo: https://commons.wikimedia.org/wiki/File:RJ45_female_connector.jpg https://commons.wikimedia.org/wiki/File:RJ45_female_connecto... [1]: The "RJ45" designation was originally an AT&T "USOC" (Universal Service Order Code). In the '70s, the FCC told AT&T that they had to allow interoperability from other companies, so the FCC had to publish a bunch of specifications; the meaning of "RJ45" became publicly specified in Bell System Communications' Technical Reference PUB 47101 "Standard Plugs And Jacks" (1979, though I think there might be an older number/revision from the early '70s that I haven't been able to track down). That (in combination with a few other technical references, such as PUB 47102), later became part of the Code of Federal Regulations, as 47 CFR part 68.
- pythonguython 1y agoWell you definitely SHOULD say RJ45. We do a lot of networking at my job and if I asked for an 8P8C connector, I would get confused stares. Say Ethernet cable, Cat 6 cable (or whatever cat), or RJ45. Sometimes being correct isn’t the right thing to do.
- rblatz 1y agoIf a contractor installed exactly what he asked for, an RJ45 jack which would be unusable for his needs he would have no grounds to stand on to demand it be corrected without paying more. By specifying the technically correct name as well as the colloquially recognized name he is being precise and accommodating.
- pythonguython 1y agoIf a contract requires RJ45 terminated Ethernet patch cables and the contractor delivers keyed RJ45, they have not delivered because RJ45 doesn’t even have the correct conductor layout to act as an Ethernet cable. Contracts call for RJ45 all the time and there are no mixups. You’d probably find it quite difficult to even find vendors for keyed RJ45
- willis936 1y agoI know this feels like a technically correct gotcha, but in fact is not. Do some parametric searches on digikey and flip through some manufacturer catalogs. If you go out of your way to misinterpret industry standard jargon you won't be paid for your work and you'll lose the contract.
- dontdoxxme 1y ago2.5GBASE-T? But I do 10GBASE-T over one. Provided it has Cat 6A cable inside it and has been tested to IEC 60512-9-3 & IEC 60512-99-002. (See https://ieee802.org/3/bt/public/oct15/Draft%20of%20IEC%2060512-99-002.pdf https://ieee802.org/3/bt/public/oct15/Draft%20of%20IEC%20605... for some fun photos of what happens when PoE is disconnected on a connector before IEC 60512-99-002...).
- timerol 1y agoThe combination of "When documenting" and referencing "J3" indicates that dlcarrier is referencing a limitation of a specific port on a product that they worked on, not a set of global limitations on any 8P8C connectors
- dlcarrier 1y agoI had assumed that the wires in the jack would rest along the bottoms of the blades in the plug, but I guess if it was never designed for high current applications, the contact area wouldn't be a consideration. It took a few tries to get it right, but it's amazing that PoE is even an option given how far it is outside of the scope of what the cables and connectors were designed for. I've heard of locations that use it for power, instead of 120 V outlets, because it's cheaper and safer and most portable high-current appliances use batteries, while fixed high-current appliances use 240 V outlets. Hot plugging is always a challenge, especially with direct current, and negotiation prevents that from being a problem while making a connection, but I never considered that unplugging isn't negotiated first. I wonder if IEC has ever considered using a locking latch, like an EV charger. I have a PoE camera that I sometimes unplug to restart it, when it freezes up and I can't restart it from the web interface. I'll be sure to turn that port off first, before unplugging it.
- DHowett 1y agoIf you can turn the port off and then back on remotely, perhaps you can skip the unplugging part completely? I know that some managed PoE switches even offer a button to power cycle a port.
- OhMeadhbh 1y agoRight. RJ45 was sort of like an 8P8C, but had a thing on the side so you actually couldn't plug a "real" RJ45 cable into a "normal" 8P8C slot.
- bigfatkitten 1y agoRJ45 specified the entire interface (ie which wires did what), not just the connector. The “what” was of course not Ethernet.
- benlivengood 1y agoAnd Molex power connectors are actually AMP Mate-n-Lok connectors. I didn't learn this until this year...
- dcrazy 1y agoWhich “Molex connector” are you referring to? The ATX spec specifically specifies Molex Mini-Fit part numbers, and claims this is for compatibility with PCIe: https://cdn.instructables.com/ORIG/FS8/5ILB/GU59Z1AT/FS85ILBGU59Z1AT.pdf https://cdn.instructables.com/ORIG/FS8/5ILB/GU59Z1AT/FS85ILB... Is Mate-n-Lok perhaps a compatible product from a competitor?
- fredoralive 1y agoIt’s the one the diagram of connectors calls “peripheral power connector” but the document doesn’t seem to go into details for it. Basically the original PC drive power connector, so 5.25” drives, older hard discs, optical drives etc. use it, in the latter cases it’s been replaced by the SATA power connector.
- numpad0 1y ago"Molex" usually refers to flat 4 pin AMP 1-480424-0 or Molex 8981-04P connectors(part number taken from random pdf on the Internet[1]). Confusing as it is... Actual Molex Mini-Fit are rarely colloquially referred to as Molex. 1: https://community.intel.com/cipcp26785/attachments/cipcp26785/intel-optane-ssd/2893/1/developer_specs_ATX12V_1_3dg.pdf https://community.intel.com/cipcp26785/attachments/cipcp2678...
- ssl-3 1y agoI've heard it argued that "Molex" means any extruded-pin connector. Like "Kleenex" means any facial tissue that is meant to be sneezed on. (Both uses are wrong, but both also tend to promote efficient communication.)
- SAI_Peregrinus 1y ago
- aruametello 1y ago_o/ 100% guilty here, ouch. also never saw a 8P8C "keyed, real rj45" connector in person.
- mayli 1y agoYeah, I learned that rencently, engineers are dumb on naming things and remember the namings.
- TZubiri 1y agoAnother, it's not an API it's an backend to backend http server, (but we know what you mean)
- brudgers 1y agoWhile your preferred specification is excellent, It’s “an ethernet port” in ordinary usage. Or “ethernet jack” in more technical contexts and entirely sufficient for Ali Express.
- spauldo 1y agoThat does you no good in my line of work, where it's just as likely to be a serial port.
- skissane 1y ago> While your preferred specification is excellent, It’s “an ethernet port” in ordinary usage. Or “ethernet jack” in more technical contexts and entirely sufficient for Ali Express. Right, in your average 2020s home or office, "Ethernet" is almost certainly 8P8C (commonly known as RJ-45). In decades past it was more ambiguous – in the 1990s, coax – ThinNet/10Base2 – was still reasonably common; even the older ThickNet/10Base5 would still occasionally be encountered. So to some extent, being specific is a bit of an "old timer" trait–a habit picked up decades ago when it was still important, now maintained when it is rarely still necessary. But even in the 2020s – in a factory, it could easily be M12 instead. Or even a mix of both – 8P8C in the offices, but M12 on the factory floor. Honestly, even in a home environment, I hate how fragile and easily unplugged 8P8C connectors are (the worst part is when they get slightly pulled out, so they still look like they are plugged in, but the connection is dead or flaky). I've thought about using M12 at home before, but it probably wouldn't be very practical.
- RF_Savage 1y agoM12 gets old quick if you do a lot plug/unplug cycles.
- brudgers 1y agoin the 1990s, coax – ThinNet/10Base2 – was still reasonably common In the 1990's they were extremely uncommon and ethernet was rare. People had dial-up if they had anything at all and only a tiny fraction of people even had that.
- noobermin 1y agoAfter googling for an image of that, jesus christ you learn something new everyday.