Can Connectors

We are wiring up our Falcon motors and I love the connectors that come with them. But I can’t seem to find any wires to purchase that would connect to those, then go to the RIO or PDP panel. I’m looking for something like this, but with only a connector on one end of the wire:
https://www.andymark.com/products/spark-max-can-cable-2-pack?via=Z2lkOi8vYW5keW1hcmsvV29ya2FyZWE6Ok5hdmlnYXRpb246OlNlYXJjaFJlc3VsdHMvJTdCJTIyYnV0dG9uJTIyJTNBJTIyc2VhcmNoJTIyJTJDJTIycSUyMiUzQSUyMmNhbiUyMiUyQyUyMnV0ZjglMjIlM0ElMjIlRTIlOUMlOTMlMjIlN0Q

Or should we just use a pwm cable and pull out the center pin?

Any suggestions on best practice?

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REV Robotics sells CAN extension cables. To connect to the RIO and PDP just cut the connector off and strip the ends of wires.

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A couple options here.

If you’re looking for completely COTS cables, than a PWM cable would likely fit the bill here. I wouldn’t even both clipping the middle pin. I don’t see it causing any harm being there, and then you’ve still got a usable PWM cable should it be repurposed down the line.

Another option, is to purchase wire from REV along with some connectors from andymark allowing you to make custom length cable runs. ​

Edit: It would also appear that REV sells CAN wire extension cables (as noted by Patrick above). This would also be another good COTS option.

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The wire from REV, looks to be exactly what I want. Thanks so much!!! For today we are using the PWM wire, and pulling the red wire. See the attached pic for what we did. But I will be

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Down the road if you want to make your own. Those “PWM Cable” connectors are called “Dupont Connectors” You can buy pre-twisted CAN wire or wind your own yellow+green wire and then cut and crimp to length. Just don’t cheap out on the crimper. A good crimper is worth the little extra up-front cost.

Molex has some both latching and non-latching connectors that work even better for us. The Dupont connectors use a plastic lever per pin to secure the termal pin.

Molex connectors are the same shape (non latching) and use metal pieces on this terminal to secure them to the housing. We get them from Digikey.

I recommend buying CAN wire from CTRE instead. You save money that way if I recall correctly. Also, I would buy it in large quantities and since CTRE just gives you one long cable, you should take an empty 3D printing filament spool, spool up your can wire in one of those, and then always just cut what you need. Using 36in segments just leaves you with random odds and ends (wasteful) along with being hard to store usually.

Maybe if you’re dead set on using 22 AWG can wire vs. 20 AWG it would change things.

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Thanks for the tip! I’ll look into this probably for our team this year. I was thinking the 36" lengths weren’t ideal when I saw them, but didn’t see can wire readily available from the other standard suppliers when I looked (I typically don’t buy straight from CTRE. Much rather buy from a Canadian reseller).

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I’ve never cared for the stock CAN BUS connectors. I had used these in place of the stock connectors:

Digi-Key Components:

WM1845-ND
WM1841CT-ND

WM1850-ND (I clip the tabs off of these since they aren’t mounted in anything usually)
WM13070CT-ND

The tool is the caveat here… it’s expensive. There are cheaper versions if you search around, but in my experience of using these for work, it’s worth the investment if you’re going to go this route.

Molex 0638190000 Crimper (Ouch, I know. With the cheaper versions out there, you have to be diligent in crimping the pins)

Just another option.

Here is a great discussion on everything CAN connectors:

This doesn’t mean you have to get the $100 unit. Dupont connectors are light enough that you don’t need a ratchet and release, or even one with dual leverage (though that’s a good idea especially for students with little hand strength). What you do need are jaws that are at least 7/32" thick (parallel to the pivots), and anvils with those deep, narrow profiles that don’t close up completely (so you can’t overdo it), and a spring to re-open is definitely handy.

I have a ~$12 crimper from about 20 years ago from Radio Shack that’s less than 7" long, with no ratchet and a single pivot point that hasn’t let me down since I figured it out. Apart from stripping the wire correctly and inserting it into the connector to the right depth, the (counter-intuitive) key to crimping these in almost any crimper is that the open end of the connector faces into the anvil, and the pin pushes against the closed side of the connector. For mine and a lot of mid-price ones, you do have to crimp twice, once for the wire and once for the insulation.
There appear to be a number of even better ones on the market near the $20 price point today. If you’re going to pay more than about $30, get one which has thicker jaws and a double set of anvils and pins, so you can crimp the connector in one step rather than two.

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Why not by two 1 green 1 yellow spools of 20 or 22 AWG wire? You can make any length you need by carefully twisting the wires together with a drill and then cut the the wire to the shorter lengths you need. I get the amount of wire I need at a cheaper price.

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This was mentioned above. Which is cost effective for you comes down to a matter of scale, and the relative availability of labor vs dollars. If you’re going to use 100’ of CAN in a year and have a small budget, making your own is almost certainly worthwhile. If you have more budget than labor, just pay for it. If you’re going to use less than 20’, again it’s false economy to make your own, unless you decide to use wire you already buy (likely not yellow and green) and are confident you won’t do any damage to the wire with the drill.

Indeed! I more-so meant don’t buy the “cheapest” pair you can find.

I have always wondered, does anyone run (or is there any benefit to running) shielded CAN cable?

CAN cable is normally twisted, which provides a good bit of shielding. VHF antennas are receptive based on the area of their loops. Twisted wire alternates “positive loops” with “negative loops”, essentially resulting in no area, and therefore minimal vulnerability to interference.

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The twisted pair configuration has the benefit of being able to reject a lot of the induced noise from external electromagnetic fields (noise).

Shielding is a different way of keeping noise out of your system. the shield is placed between your vulnerable signal conductor and the noise source and provides a low impedance path for the noise currents, if the shield is terminated correctly.

Adding a shield on top of a twisted pair will enhance the rejection of induced noise significantly but I have not seen evidence that this is necessary in FRC robots. The shield will also change the characteristic impedance of the transmission line quite significantly. Unless you have the ability to ensure that the signals are not being distorted significantly by the change in impedance, it is best not to used shielded twisted pair for your CAN connections. Terminating shields properly and in a robust way is not fun either.

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Thank you both for the excellent answers. That does seem to make a lot of sense.

CTRE CAN wire:

http://www.ctr-electronics.com/can-bus-cable-10ft.html

$ 0.39 per foot at CTRE. Buy 1000 feet, and get it for $0.25 a foot.

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We have 100% switched to Wago Lever-Nuts for our CAN wiring. Yes, they are a bit bulkier, but the speed of install and ability to make quick changes wins out every time. No more bad crimps. No more bent pins. No more not-quite-seated connections. You can visually inspect the wire in the connector and know it’s in right. And we can use the same series for power when needed. Oh, and they make FAST field side fixes. They also come in 3 or 5 lever versions for power splits.

https://www.wago.com/us/wire-splicing-connectors/compact-splicing-connector/p/221-412

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