CAN Cables

[Hugh Meyer]

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

[ratdude747]

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...

[eStop Robotics]

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/...d&productId=34

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

Good Luck to all the Teams!!!!!!

[blu28]

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?

[Mike Copioli]

Originally Posted by blu28

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/sh...an+cable+video

[otherguy]

You may also find the CAN guide and video on my team's site helpful:
http://team2168.org/index.php/resour...10-can-jaguars

[Bryscus]

Originally Posted by Geek 2.0

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

I'm at a loss to understand how twisted pair helps you when CAN doesn't use a differential pair and 5e isn't shielded...

- Bryce

[Mike Copioli]

Originally Posted by Bryscus

I'm at a loss to understand how twisted pair helps you when CAN doesn't use a differential pair and 5e isn't shielded...

- Bryce

CAN does measure the voltage difference between CAN high and CAN low, this is why it is used in HIGH noise environments such as automobiles.

[eStop Robotics]

The decision is often...buy it or build it?

Given the limited amount of programming and development time during the robot build portion of the FRC season, it makes sense to focus on the implementation of CAN in a robot design rather than spending time fabricating cables.

Building CAN cables is not rocket science but it is one more thing to do on a long list of tasks in a typical robot build.

If you decide to build it...see the Texas Instruments website for Stellaris Jaguar CAN information.

If you decide to buy it...see the eStop Robotics website for CAN cables inclduing a CAN Starter Pack.

Either approach will give you access to the advantages and features of a CAN enabled FRC robot.

[Mike Copioli]

Good advice you may also visit:

http://www.andymark.com/product-p/am-0967.htm
http://www.crosstheroadelectronics.com/Cable.html

Andymark has a do it yourself kit, CTRE has both premade and do it yourself along with a video on how to assemble your own cables.