CAN Cables

Hey, just wanted to know where you all get your cables. Anyone make their own? It seems to make sense, because you never need as much as they give you or you never get enough.

If you do make your own, where do you get supplies?

If not, where do you buy your cables?

The CAN cables aren’t the same as the kind of phone wire you’d find at radio shack, so we make our own. It’s easy if you have the tools

I think you meant the cable is the same as Radio Shack, just the pin outs may be different. Shop around their are other places to buy supplies for less cost.

We’ve made all of our CAN bus cables. Get an good phone terminating tool. Four and six conductor flat phone cable and RJ11 4 conductor and 6 conductor terminals. Just pay attention to wire orientation.

We used CAT5e cable, with stranded wire. We had noise issues with normal phone cable.

Instructions and Digi-Key part #s can be found in the last chapter of this PDF

More info and the BDC-COMM app (connect laptop to CAN) can be found on the Luminary Micro site

Did you just leave 2 of the wires unconnected? Sounds like an awesome idea!

Yes, we left the Brown Pair unused.

Where did you get your endings/cable/crimper?
I don’t know if Radio Shack has the stuff, but I’m pretty sure some home improvement stores have them. Anyone know?

Everything except the supplies for the RS232 cable (haven’t found any stores that stock 6 pin RJ12 connectors), can be found at Radio Shack at typical convenience prices (about twice the price for RJ11 ends as Digi-Key). The Getting Started Guide at Luminary Micro’s site (which can’t be direct linked like in my last post) has the part numbers for Digi-key and instructions for the cables. If you dont want to spend the money on the modular adapter and 6pin cable for the RS232 Cable then you can order some RJ12 some sort of DB9 connector (you might have some of these from previous years).

We made our own. As others have indicated, getting the RJ-11 and RJ-12 isn’t too bad - they’re available at most places online (digikey, allied, mouser, newark, etc), and at Radioshack (our local store had both available). Add in a cheap $20 crimper, and you’re set.

As for the wires… we got ours from our primary sponsor, Boston Scientific. As it turns out, one of the testing labs here was doing something with some wire terminals from another company. To get the terminals, they had to buy the whole cable (about 4 feet long per unit), but all they needed was the terminals on it. So they cut off the terminals, and were going to trash the rest of the cable. We snatched it up :slight_smile: It’s got 4 wires running through a nice, flexible outer sleeve. The only downside was the color coding - two white and two black. That just means we had to use a multimeter to ensure we got them in the right order :slight_smile:

CAN is ridiculously tolerant of errors (I don’t know what baud rate the FRC Jags operate at). You can just take two 28AWG wires or so, vise-clamp one end, put the other ends in a drill, and make some twisted-pair to carry the signal. (And then sleeve/braid it if you want).

We found most of our supplies at our local ACE hardware store, including wire, connectors, and crimpers. Be aware that the crimpers you need will be six conductor crimpers. One of the connectors (the one with the serial cable) must be 6 wire. The rest can be four wire. This mistake wasted several days while we had bad connections on our serial cable.

You can find everything (connectors, crimper, wire) at your local Lowes or Home Depot. They’re pretty standard for home phone installations. Just make sure that you get the 6P6C RJ-12 connectors and associated crimper. Also, don’t forget to flip the connector on one end to get pin 1 to pin 1 etc. connectivity.

Good luck,

Mike

ok, i having some difficulty on how the wires are to be built, are the wires in the CAN cable reversed (AKA 1>6, 2>5, 3>4, 4>3, 5>2, 6>1)

and if that is so, would this work for the connection to the cRIO?

DB9 RJ12 Jaguar
3 -TXD 6 1 - RXD
5 2
100 Ohm 4 3 - CAN H
100 Ohm 3 4 - CAN L
5 - GND 2 5 - GND
2 - RXD 1 6 - TXD

I would like not to have to build a specail cable for just going from the adapter on the cRIO to the first Jaguar. I would perfer to have all the specal changes in the the DB9 to RJ12 adapter.

Thanks!

the wires are NOT reversed. it is a through cable.

if you are using the db9 adapter with the rj12 jack, be aware that many have reversed pinouts. i killed one finding that out… sure, they were $.50 a pop, but it still was annoying.

if you have any questions, be sure to read this:

http://www.chiefdelphi.com/media/papers/2433

it’s a document I recently wrote with everything you would ever want to know about making the wiring work for CAN.

Only connect the two center pins. Pins 3 & 4. If you connect them all, one is a ground connection and will create a ground loop. The only signals needed are the CanHigh and CanLow. This is a balanced differential circuit, so no ground connection is required.

If you have a ground loop and one Jaguar has a heavy load and another does not this situation will cause noise. We smoked several Jaguars last year and after we disconnected the ground connection the system was much more stable.

The only cable that needs the ground pin connected is the serial cable that connects to the cRio or computer. The ground wire would only be required on the first Jaguar if you are using the serial port as your CAN gateway. If you are using a 2CAN or other outboard device then only connect the center two pins.

Be sure to have the 120 ohm terminator at the end of the line.

-Hugh

actually, for robotics use, TI recommends 100 ohm resistors, not 120. see the jaguar manual

every document i have read has said to use all 4 connections. if they did not want all for they would have used only 2 pin connections on the jacks (they make them like that as i see computer modems with them all the time). they instead used four. if it was such a bad problem, they would have left them out.

just my personal opinion…

Greetings from eStop Robotics!!!

We have CAN cables to connect your Jaguar Speed Controllers to your cRio! We can supply you with terminators, the Serial to CAN interface cable, 12 inch, and 36 inch CAN cables.

http://www.estoprobotics.com/estore/index.php?_a=viewProd&productId=34

These cables are great for making the CAN communications work in your FRC Robot!

Good Luck to all the Teams!!!

I misread the pinouts and ended up connecting all 6 pins. I have the pairs connected from the outside in, which is to say that one pair is on pins 1 and 6, reversed so that the wire on pin 1 on one end is connected to pin 6 on the other and vice versa. Likewise there is a pair on pins 2 and 5 and also one pair on 3 and 4. Does it hurt to have the extra pair on the outside? What about wiring the one marked at no connector that corresponds to the ground?

I assume you are trying to make cables for to communicate between Jags and not a serial adaptor. Below is a link to a thread with a video tutorial on making CAN cables.

I hope this helps.

http://www.chiefdelphi.com/forums/showthread.php?t=99253&highlight=can+cable+video