Odd glitches in CAN rig

[hedgeberg]

Hello all
So my team decided to connect to our Jaguars using CAN this year for the first time. We got the Jaguars to connect to BDCCOMM, updated the firmware, bought a pre-made RS232/CAN cable, etc. Everything seems like it should work fine.
However, we recently noticed a really odd glitch where the first and third jaguars in a 4-jaguar chain, regardless of what their id is, are the only ones to work. regardless of how we order our jaguars or replace cables, we cannot get the second and fourth nodes to indicate that they have established a network connection.

Any ideas as to what the issue could be and how we could fix it?

[dyanoshak]

Check your CAN cables. This usually indicates that the can cables are not "straight through", meaning pin1->pin1, pin2->pin2, etc.

You will see every other Jag work because each cable flips the signals, so after two cables, the signals are correct again.

See pages 25-26 of the Jaguar Getting Started Guide found at www.ti.com/jaguar. There is a diagram showing the correct orientation of the modular connectors when the cable is held flat.

-David

[hedgeberg]

We unfortunately did not have time to test all cables, but we did test the cable between nodes 1 and 2 and found it to be straight through and continuous on all pins. Also, we did switch around our cables to see if that would make any difference, and it did not. Is there another possibility for what is wrong?

[Cecil]

Have you enumerated them all properly? They need to be told what number in the bus they are, so you can code them accordingly. Watch for multiple Jaguars with the same ID also - this can be determined by a fast flashing orange light.

[hedgeberg]

They are all enumerated properly.
We have enumerated them 2-5, so as to allow for firmware updates
they are also up to date on firmware, and we did use the most recent BDC-COMM version.
However, I did just realize a possible problem. We are using unmodified RJ12 cables. Would we need to modify these at all for proper function, based off dyanoshank's previous statement?

[Cecil]

Are you using the version 101 firmware from FIRST's site? Or the version 99 that came with the software? I don't know if this would affect it at all, but it may. Also, those cables should work. If they are flat cables, look at them this way: All stretched out and flattened, one connector should be face up, and the other should be face down. If not, you will have to look at the connector to see if the wire order is exactly the same in both connectors.

[dyanoshak]

Originally Posted by hedgeberg

However, I did just realize a possible problem. We are using unmodified RJ12 cables. Would we need to modify these at all for proper function, based off dyanoshank's previous statement?

You will probably have to modify them. Check them like Cecil and I suggested; hold the cable flat and look to see if the tabs are opposite each other (one up and one down).

[hedgeberg]

So, we checked our RJ12 cables.
The crimps face the same way, so we have some rewiring to do.
We're thinking we're going to split the wire open and solder wires at the middle
any advice as to what cables to solder together/could we get a wiring schematic so that we can rig this together?
Thanks guys

[dyanoshak]

Originally Posted by hedgeberg

So, we checked our RJ12 cables.
The crimps face the same way, so we have some rewiring to do.
We're thinking we're going to split the wire open and solder wires at the middle
any advice as to what cables to solder together/could we get a wiring schematic so that we can rig this together?
Thanks guys

Again, there is a diagram and a pinout of the cable in the Getting Started Guide I linked to above.

That being said, I don't recommend splitting and soldering the cables. The wires are small and you will have to individually insulate each one to prevent shorts.

It is much less of a hassle (and less error prone) to just buy a cheap crimper, bulk 6 conductor cable, and 6p6c connectors from Radio Shack, Fry's, or your favorite electronics shop and make the cables correct yourself. The Getting Started Guide has part numbers for the cable pieces if you need to order them online.

Note: You only need 6 conductor cable between the Serial adapter and the first Black Jaguar. For the rest, 4 conductor cable and 6p4c connectors will suffice... but why have two kinds of cables to keep track of?

[hedgeberg]

One of our mentors is running home right now to get a crimp tool and some 6p6c cables
hopefully this works
thank you both so much. We'll tell you how it goes.

[otherguy]

If you get stuck, we have a guide on our site with videos on how to make all the cables you need for CAN:
team2168.org/index.php/resources/electrical/210-can-jaguars