Flexible cable with many conductor and robust connector. - Page 1
Forum section: electronics / projects

author: Twistx77
author_rank: Regular Contributor
timestamp: June 21, 2017, 11:33:04 am
content: Hi,I'm trying to find a flexible cable with more than 14 conductors to connect two devices. They need to be as small as possible but the connectors has to be as robust as possible. I need something like a USB Type C. I might end up using that but I would like to know if there are other alternatives. I would like to prevent someone connecting the device to a standard USB and ending up damaging something.I plan to run a SPI bus as well as some other digital signals through the cable.Any help will be greatly appreciated.Thanks.

author: jbb
author_rank: Super Contributor
timestamp: June 21, 2017, 07:25:26 pm
content: Maybe a D-Sub connector? They are moderately tough and have fastening screws.But don't use DB-9 because there are still a lot of RS232 serial ports in use and people might get confused.

author: testian
author_rank: Regular Contributor
timestamp: June 21, 2017, 08:12:01 pm
content: Ribbon Cablehttps://www.buerklin.com/en/plug/p/70f9702HDMISCSI

author: Cerebus
author_rank: Super Contributor
timestamp: June 21, 2017, 08:30:44 pm
content: There ought to be something cast in stone around here as to what information is always needed before a question like this can be answered, and is almost always omitted.A non-exhaustive list would include:DistanceBandwidth (modulation rate)Edge speeds that must be maintained at outputImpedanceEncodingExtremes of voltage and currentTransmission standard (if there is one)There's a big difference between getting a 10 kbit/s differential signal over one metre and a 200 Mbit/s signal over 50 metres.Provide some of the missing data and people will be much better placed, and much more inclined*, to give you a helpful answer.*Sometimes I, and I suspect this is true for others too, look at a question that's missing lots of essential data and think "Am I prepared, at the moment, to go through the rigmarole of teasing out what's needed for a proper answer?" and on my more curmudgeonly days the answer is "no".

author: leblanc
author_rank: Regular Contributor
timestamp: June 22, 2017, 01:54:12 am
content: What about LEMO connectors?Potentially suitable series:https://www.lemo.com/en/low-voltage-connector/b-connectorhttps://www.lemo.com/en/low-voltage-connector/2c2g-series

author: rx8pilot
author_rank: Super Contributor
timestamp: June 22, 2017, 04:06:24 am
content: I really like Lemo when robust is a top concern. They can accommodate any signal from fiber to RF to power. Be prepared for the cost and a challenging termination experience.Sent from my horrible mobile....

author: technix
author_rank: Super Contributor
timestamp: June 22, 2017, 10:22:44 am
content: You may get some mileage out of the DisplayPort connector. It is slightly larger than HDMI, but the killer feature of this connector is that it is locked but not screwed - there is a latch on the connector that need to be held down to disengage the connector.If you can multiplex some signals, for example by using an remote MCP23S17 for the GPIO signals or straight up adding a remote microcontroller, you can try squeeze the signals into an Ethernet cable.

author: Ian.M
author_rank: Super Contributor
timestamp: June 22, 2017, 10:51:19 am
content: Its not a good idea to misuse any of the common consumer connectors or cable types that users normally expect a plug & play experience from for your own non-standard interface. Its actively *STUPID* to use one for an electrically incompatible interface such that a normal consumer device with that connector could be damaged by or could damage your equipment.I would therefore rule out USB type C, DE-9 (aka: PC serial), HDMI, and DisplayPort, and anything else that you can buy an off-the-shelf cable for in a highstreet store.Using UTP with 8P8C modular connectors ('RJ45') for purposes other than Ethernet can be dodgy. If your device outputs significantly more than the +/-2.5V signal levels used for Ethernet, you risk blowing any network port it gets inadvertently connected to, and for your device to survive all possible POE misconnection scenarios, it also needs to tolerate up to 57V between pairs.

author: technix
author_rank: Super Contributor
timestamp: June 22, 2017, 11:22:37 am
content: Quote from: Ian.M on June 22, 2017, 10:51:19 amIf you want to build your gear affordable you have to use COTS connectors.As of 8P8C a fairly safe mode of use is RS422 on pins 1/2 and 3/6 and short pins 4/5/7/8 together as ground.

author: mariush
author_rank: Super Contributor
timestamp: June 22, 2017, 11:48:49 am
content: RJ50 (like ethernet but with 10 contacts) is not that expensive. Different enough to regular ethernet but easy to crimp and easy to buy plugs.Could be a good solution if you can reduce your wire count.Also may want to look into mini-DIN plugs and headers.. 9pin sockets and plugs should be fairly cheap because they were commonly used with svideo/composite. They're also available in bigger pic counts.

author: rx8pilot
author_rank: Super Contributor
timestamp: June 22, 2017, 07:44:43 pm
content: I thought 'robust as possible' was in the original description.RJ, USB, DisplayPort are not even approaching robust in my industrial/professional world.Sent from my horrible mobile....

author: Someone
author_rank: Super Contributor
timestamp: June 23, 2017, 12:54:27 am
content: Quote from: rx8pilot on June 22, 2017, 07:44:43 pmI guess it depends on your point of view. Display port could be looked at as the start of "robust" connectors although nothing like a lemo or military 38999, its locking and has panel mount sockets. HDMI was much worse yet still saw wide use in portable equipment with reasonable reliability.

author: Someone
author_rank: Super Contributor
timestamp: June 23, 2017, 01:01:16 am
content: Quote from: technix on June 22, 2017, 11:22:37 amAutomotive is driving a wide range of cheap high speed connectors, but they're usually targeting fewer pins. Unmatable with consumer cabling there are plenty of choices available:http://www.jae.com/jccom/en/connectors/Search/Automotive

author: jwm_
author_rank: Frequent Contributor
timestamp: June 23, 2017, 01:08:33 am
content: locking IDC and ribbon cable? (rainbow hippy cable for extra coolness) I am not sure what is meant by relatively small so may be too big.http://mpsiconnex.com/wp-content/uploads/2016/01/w2b-latched.jpg

author: Twistx77
author_rank: Regular Contributor
timestamp: July 03, 2017, 09:22:57 am
content: Hi everyone,Thank you all for your answers and sorry for taking so long to respond.With all your information and all we have looked up, we haven't found anything we liked so we are going to use another approach that doesn't involves the cable.We wanted something like the USB type C because of its size, number of conductors and "robustness". It is not like an IDC which can be seen as "unprofesional" also is not ideal to be plugged and unplugged everyday expecting the same life a USB cable can have. Also size is not good. The same for DSUB cables and RJ45 or RJ50 (I didn't know RJ50 existed).I wish there were more connectors like USB type C, mini HDMI and things like that, that weren't so standard.Anyway, thank you to everyone.