convention for orientation of linear connectors on cables? - Page 1
Forum section: electronics / projects

author: k8943
author_rank: Regular Contributor
timestamp: January 03, 2019, 07:46:25 am
content: Was browsing for some 5pin JST SH connector wires and found the following (see attachment).I kind of expected one of the connectors to be flipped (upside down when cable lying flat) with respect to the other to ensure that on the PCB socket the wires always read 12345 in order from left to right.But in this picture that is not the case.Now realise have no particular grounds or basis for this expectation.Are there any conventions or best practices in this matter?ps another thing confused about: JST style socket on the board has little pins sticking up within a trench. I'd be inclined to call this "female" (because of the trench) but is it in fact "male" (because of the pins)? Making the connector on the wire - which looks male to me - in fact female because of the little holes? Confused.

author: k8943
author_rank: Regular Contributor
timestamp: January 03, 2019, 08:16:22 pm
content: hmm one day gone by and no replieseither this was a really bad question or it's incredibly difficult!

author: soldar
author_rank: Super Contributor
timestamp: January 03, 2019, 08:59:40 pm
content: My guess is this is not really a consumer cable but rather a cable mainly used to connect PCBs and the designer will be careful to make sure the connections are correct.But yes, it feels somehow "wrong".Regarding the gender of connectors it used to be that the one with the pins was male. That is the way it was with DB9, VGA, etc. But more recently there seems to be some gender confusion and/or reassignment and the rule has been reversed with HDMI, Displayport and others. For me calling the one with the pins "male" is correct. That was the convention.

author: kjpye
author_rank: Contributor
timestamp: January 04, 2019, 01:38:54 am
content: The convention used to be (at least for the D-series connectors, DB25 and friends) that the pins determined whether the connector was male or female, and the overall connector shape determined whether it was a plug or a socket.Thus the OP's on-board connectors are male sockets, and the corresponding cable would have female plugs.

author: wraper
author_rank: Unknown
timestamp: January 04, 2019, 01:45:20 am
content: You just found some stupid oddball cable. There is no good reason to do this. Normally wires should match pin numbers on both ends.

author: k8943
author_rank: Regular Contributor
timestamp: January 04, 2019, 08:21:09 am
content: male / female and socket/plug be separate and combinable categorisations clarifies a LOT.On the placement of JST SH connectors at each end of a number of wires, another datapoint might be FFC cables (as used frequently for connection Screens to boards).FFC cables seem to come with TOP-TOP or TOP-BOTTOM orientations possible. Think had the impression that TOP-TOP were cheaper and more common, but not sure.These possibilities seem in part to exist because the board connectors are sometimes UP and sometimes DOWN (contacts pressing down on the cable or pushing up against it when you clamp the ribbon down. And presumably in part according to how you want to route the cable in space between the boards (does it do a backwards somersault or not?).I'm trying to understand because the cables I get (crimping SH is too difficult so will buy them ready made) will determine the PCB routing to the connectors. And then if it turns out have made an odd choice in cable selection well the whole thing is going to be odd!These guys are selling double ended cables with SH and they look like they are all TOP-TOP, so to speak:https://www.aliexpress.com/item/10pcs-JST-SH-ZH-XH-PH-1-0mm-1-25mm-1-5mm-2-0mm-2-54mm/32807634326.html?spm=2114.search0104.3.1.3efa153flFLqBs&ws_ab_test=searchweb0_0,searchweb201602_1_10065_10068_319_317_10696_10084_453_454_10083_10618_10304_10307_10820_10821_537_10302_536_10843_10059_10884_10887_100031_321_322_10103,searchweb201603_51,ppcSwitch_0&algo_expid=c01d67c3-3545-4f6a-b68e-8a99bd18a737-0&algo_pvid=c01d67c3-3545-4f6a-b68e-8a99bd18a737

author: mvs
author_rank: Frequent Contributor
timestamp: January 04, 2019, 09:54:40 pm
content: Quote from: k8943 on January 04, 2019, 08:21:09 amYou probably mean opposite pin direction (12345<->54321). Yes all cable look like that. But you may ask the seller wich cables types they can supply. In some lots you can choose pin direction.https://aliexpress.com/item/10-st-ck-20-cm-SH-JST-ZH-PH-XH-1-0mm1-25mm1-5mm2-0mm2-54mm/32859226460.html

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: January 05, 2019, 01:05:22 am
content: Let's say you're using color coded ribbon cable. It probably follows the resistor color code. The connectors should have a molded in arrow or similar, to indicate pin 1. There's almost always something, or don't buy 'em. DB connectors will be numbered, or look 'em up. Brown is pin 1, red is pin 2, etc. Never otherwise, regardless of how the cable has to route. Hopefully it can be crimped exiting from either side to make things easy. With no color code, there's usually some indicator for wire 1. On the PCB pin 1 should use a square pad, with the rest round. With no other info you should be able to plug things in and never make a mistake. To be absolutely sure, follow the rules and also use polarized connectors. There's a special place in hell for designers that ignore this stuff.

author: k8943
author_rank: Regular Contributor
timestamp: January 05, 2019, 01:16:14 pm
content: Lots of great information. Thanks everyone!

author: reboots
author_rank: Regular Contributor
timestamp: January 05, 2019, 05:44:40 pm
content: JST uses the terms "housing" (wire-end contact housing) and "header" (the part on the PCB) for their wire-to-board connectors. I would defer to JST.The male/female/pin/socket/plug/receptacle terms are historical and seemingly obvious. But at this point they're more colloquial than standard, and likely to cause confusion. Consider industrial circular connectors, which regularly fall into baffling categories like male plugs with female socket contacts and their mating counterparts. Clinging to this terminology demands obsessive specificity.I'm not aware of a standard practice for wire order between housings, but reversing the order seems like a cruel joke unless you really need to keep the cable flat.

author: nctnico
author_rank: Super Contributor
timestamp: January 05, 2019, 05:57:56 pm
content: On most connectors you'll find a 'pin 1' designator or at least it is mentioned in the datasheet. Follow that.By the way: one of the most anoying pin reversals I ever came across is in modular jacks (RJ45 style connectors). Everyone except Motorola numbered these the same way. Things got messed up a few time when I had to design devices which connected to Motorola equipment.