Custom made Ethernet cable - Page 1
Forum section: electronics / projects

author: prasimix
author_rank: Unknown
timestamp: August 15, 2016, 02:58:41 pm
content: I need a short custom made Ethernet cable that don't have standard RJ-45 connectors but simple 8-pin 0.1" receptacles. I made one as on the picture below but wondering if someone can suggest a company that is in business of custom cable assembling or if such cable already exist under some name/model on online shops such as eBay, aliexepress, etc. Thanks.

author: botcrusher
author_rank: Regular Contributor
timestamp: August 15, 2016, 04:04:52 pm
content: O_oI don't know of anyone who does, and a cable of "this construction" is asking for a bad time. I hope you don't intend to run high speeds over that...

author: prasimix
author_rank: Unknown
timestamp: August 15, 2016, 04:09:20 pm
content: Please define high speed. I tested it with 10/100Mbps that comes out of Wiznet W5500. It's CAT5 cable cut to length with added connectors.

author: kripton2035
author_rank: Super Contributor
timestamp: August 15, 2016, 04:46:45 pm
content: if you plug it into an ethernet hub 10/100 it may workif you plug it in a switch 10/100/1000 it will surely not work.cat5 cables use differential pairs, and clearly here you are destroying the pairs (orange-green-blue ant brown)if you stick to 10bT it will work, but at a higher speed be prepared to collisions and errors.

author: botcrusher
author_rank: Regular Contributor
timestamp: August 15, 2016, 05:56:15 pm
content: To clarify, it will work on a 10/100/1000 network, but the devices will auto negotiate down.

author: wraper
author_rank: Unknown
timestamp: August 15, 2016, 06:09:49 pm
content: Quote from: botcrusher on August 15, 2016, 05:56:15 pmit will work on 1000 network without an issue unless there are 10 of such cables in series. You should try much harder to break it.

author: kripton2035
author_rank: Super Contributor
timestamp: August 15, 2016, 07:24:33 pm
content: I had once a network with 10bT hub on it. I proposed to the customer to install a 100bT switch to speed things up.at the time I did not know the importance of good cables.the network was slower after the hub-> switch exchange ! lots of errors, collisions, so on.only 2-3 computers were ok, the ones that had good cables.the other had badly paired rj45 plugs (not the right pair at the right place of the connector)I rewired the bad cables and everything went back to what they should be.

author: Monkeh
author_rank: Super Contributor
timestamp: August 15, 2016, 09:11:10 pm
content: Quote from: kripton2035 on August 15, 2016, 07:24:33 pmThe pairs are all effectively identical. It doesn't matter which goes where so long as the pairs aren't split.If the pairs get split, you obviously can't expect anything to work.A cable like this will work just fine, although a little more care could be taken. Use a USB2, USB3, or 1394 port on the front of a computer sometime - same thing.Why's the blue pair split around the orange, though?

author: magetoo
author_rank: Frequent Contributor
timestamp: August 15, 2016, 09:19:57 pm
content: Perhaps relevant:

author: prasimix
author_rank: Unknown
timestamp: August 15, 2016, 09:26:12 pm
content: Thanks all for replies. I tried not to split pairs. 8-pin connector looks like this:

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: August 15, 2016, 11:01:08 pm
content: Digikey made custom cables for me years ago, you send them a drawing, more detail is better, and they'll give you a p/n and a cost.I don't know if they still do that.

author: helius
author_rank: Super Contributor
timestamp: August 15, 2016, 11:39:49 pm
content: The signal integrity of those ends is not the problem, the problem is if you don't match the +/- pin pairs with the actual twisted pairs in the cable.There are companies that can make custom cables like this.http://www.showmecables.com

author: T3sl4co1l
author_rank: Super Contributor
timestamp: August 16, 2016, 08:51:40 am
content: Quote from: kripton2035 on August 15, 2016, 07:24:33 pmThere's your problem-- hub. You can't get collisions if you use a proper switch or router that directs packets where they belong.All Ethernet modes are "unusually robust": 10Mb is slow as molasses; 100Mb is fast, but not terribly critical of moderate mismatch (one jumper is fine, but as wraper said, ten in a row might not work out so well), and 1Gb measures the line and compensates for its frequency response, to an extent. If nothing else, an exceedingly poor line will fall back to a lower, less susceptible mode, maintaining a connection, if not a fast one (which is still good enough for, say, connecting to your average cable/DSL modem*).*Well, U.S. average.Tim

author: prasimix
author_rank: Unknown
timestamp: August 16, 2016, 09:01:17 am
content: I don't know how proper is my switch, but for interchanging SCPI commands and some "debug" textual info that could be up to "massive" 100-200 bytes in a row it seems that it works as expected with 10 and 100Mbps. I'm not using it for video streaming, high speed data acquisition, etc.

author: kripton2035
author_rank: Super Contributor
timestamp: August 16, 2016, 02:14:50 pm
content: Quote from: T3sl4co1l on August 16, 2016, 08:51:40 amyou did not understand : the hub with 10bT was FASTER than the switch with 100bT on bad connected cables.

author: Monkeh
author_rank: Super Contributor
timestamp: August 16, 2016, 02:15:48 pm
content: Quote from: kripton2035 on August 16, 2016, 02:14:50 pmBecause your cables were obnoxious garbage. Not the case here..

author: kripton2035
author_rank: Super Contributor
timestamp: August 16, 2016, 05:19:41 pm
content: no the cables were good, only they did not respect the pairing of the wires, so some pairs were splitted.I did not change the cables, I only removed the rj45 and re-fitted one with each wire pair at the right place.and everything went back in order, 10x faster than before.

author: Monkeh
author_rank: Super Contributor
timestamp: August 16, 2016, 05:20:41 pm
content: Quote from: kripton2035 on August 16, 2016, 05:19:41 pm... so, they were not good, they were garbage.

author: C
author_rank: Super Contributor
timestamp: August 16, 2016, 05:32:37 pm
content: prasimixEthernet is not a yes or no.When you start getting problems, you start getting receive errors and requests for retransmit. Interface should have some status values to tell you this.A retransmit request for example could be from a packet drop or any of the many errors in the transmit path.Total distance between transmitter and receiver will effect this.When you start having to retransmit, you are lowering total bit rate possible.Your SPCI is at a higher level then the above and would only show time delays.kripton2035The cables are part of a system. The connectors and cable is the cable system which is added to total system. One fail effects the total system.

author: prasimix
author_rank: Unknown
timestamp: August 17, 2016, 12:49:40 pm
content: Good, does measuring packet loss that provides ping command can be used as good indicator about connection health?

author: Monkeh
author_rank: Super Contributor
timestamp: August 17, 2016, 12:52:09 pm
content: Quote from: prasimix on August 17, 2016, 12:49:40 pmNo. However, your cable is less of a bump than the average wall plate termination. Don't worry about it.

author: bicc1306
author_rank: Contributor
timestamp: September 30, 2016, 02:59:31 pm
content: I found one UK company manufacturing custom made ethernet cable. See below.http://www.ethernetcables.co.uk/