CAN Bus Connectors

Hello!
I’ve been searching around for what CAN bus connectors are commonly used, easy to install and are semi-immune to robot turbulence. We tried CTRE CAN Connectors with 20 AWG ferrules and a crimper similar to this one. However, we had at least a couple ferrules fall out of the connectors mid-match, leaving down-stream CAN devices inoperable. We’re trying to avoid that issue this year and we’re trying out these locking JST-SM connectors with a male and female connector on each CAN device. I’m curious what other teams have done and especially if there is one great solution to this problem.
Thanks!

We use PWM crimps as they are cheap and have been reliable so far. We also use the ctre CAN connectors for emergency repairs where we don’t have time to fully crimp them.

I would highly recommend Wago Lever Nuts

https://www.wago.com/221/us/

They are robust, and super quick to install/check for diagnosis. They even have higher rated ones that I’ve seen used for motor controller outputs, though I would not recommend that myself.

Are you crimping your own pins on and installing them in housings, or cutting pre-made pwm wires and terminating them onto the can wires?

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We have used the locking JST SMs the last two seasons and would recommend them. Make sure you buy the right crimping tools and train with them heavily before you use them on your comp bot.

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Our team has also used something similar to if not the same as the JST-SM connectors (i have no idea on the brand)and have worked without a problem. I would recommend setting a standard as to if the green is on the left or right and such before implementing them. If one talon is backwards the whole thing is messed up.

We crimp our own pins on and install them in housings. The crimping isn’t easy and we make mistakes, but the crimps themselves are very cheap.

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I’ve been beating this drum for a few years. These IDC tee connectors are almost perfect. No soldering or crimping required and if one fails, you lose a single motor, not half the robot:

https://www.superbrightleds.com/moreinfo/wire-connectors/clear-24-18-awg-t-tap-wire-splice-connectors-single-dual-channel/4157/

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Those straight connectors would work, but the T connectors go against the CTRE-specified daisy-chain topology. Do they pierce the wire inline? Are they re-usable, and do they damage the wire preventing re-use? Seems like a great connector to have in the arsenal.

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Do you have any pictures of the IDC tees on the robot?

Edit: Nevermind. https://www.chiefdelphi.com/uploads/default/original/3X/5/7/576071b764fe7e283ca72d853c0d9f52a93636fa.jpeg

The CAN bus specs allow branches from the main bus up to 12" long. We’ve run these connectors successfully in the 2018 off season, and the entire 2019 season.

[edit] here’s a picture of the connectors on our 2018 robot:

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For FRC applications it’s fine to do this, as long as the “branches” from the main bus aren’t too long.

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I’m a big proponent of the star topology, and I’m still not sure why CTRE recommends against it. With the lengths of bus that FRC robots are using, I don’t think the impedance differences would amount to any real issues. I just know it’s heavily recommended against whenever it comes up.

Those look way neater than our implementation of the wago lever nuts. Just the orientation looks like it would be easier to route neatly. Lever nuts force both wires to come into the connector from the same direction, much like a wirenut.

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These are great, if you want something pluggable these are similar option that we’ve also used. https://www.amazon.com/Pluggable-Connectors-Universal-Terminals-Wire-Stripping/dp/B07PRZMYD4/ref=pd_sbs_469_2/142-0495616-1245268?_encoding=UTF8&pd_rd_i=B07PRZMYD4&pd_rd_r=679345e6-8702-11e9-80a7-897b33f3ad6d&pd_rd_w=e5eFU&pd_rd_wg=tKPuI&pf_rd_p=588939de-d3f8-42f1-a3d8-d556eae5797d&pf_rd_r=11V3D41J1ATJES4K993V&psc=1&refRID=11V3D41J1ATJES4K993V

Just take care with those. We tried them and found they don’t really snap tightly together like powerpoles, so use at your own risk.

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Something like the JST-SM connectors is a good idea. The best thing is for the connector profile to resemble the wire (to be long and thin) because the geometry determines the impedance. Using the WAGO nuts or things like that is not a great idea. People kinda get away with it but they are not testing it and getting lucky-ish (seeing how many problems CANbus problems they have, measuring the impedance etc).

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94 posts were split to a new topic: Merits of Star Topology for CAN Bus

We use Anderson power poles to connect our CAN bus

We’ve used the CAN Connectors with zero issues. Dump the ferrules.

David

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switch to something smaller

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We used XT30s this passed season, and while many people dont like them for CAN, and it does take more time to prepare controllers, we really enjoyed using them. It made swapping motor controllers easy (even though I’m not sure if we ever had to after build season) and we never had CAN bus based issues.