We’ve used stubs in the past, usually about the 4 inches that come directly connected to the device. But, there are two sets of wires coming out of each motor controller and I’m not certain what we should be doing with the other set – seems to me that all they do is extend the length of unterminated bus.
We started soldering all connections last year. It is now the new standard for our team. Historically we had lots of electrical issues but we had near zero last year.
3 Likes
Wait, do you mean that you use the roboRIO CAN bus? I’m struggling to understand how you can use neither the RIO bus nor an external USB device bus.
Said differently, the default RoboRio CAN bus is CAN 2.0 (@ 1Mbps).
1 Like
Sorry for the misinterpretation. I’ve edited my response above.
Nice!
Depends on your motor controllers – SPARK MAXs and Krakens make for easy removal (and replacement) of the second twisted pair, whereas anything with perma-pigtails doesn’t.
Understood. Using IDC tees with the double-pigtail arrangement that ships with most CAN devices seems like an odd combo, but in a stub topology, it fits. That’s mostly why I asked.
I asked about stub length partially because I believe the max stub length for 1 Mbps CAN is ~0.5m, whereas 10 Mbps CAN has to be much shorter. We didn’t get around to experimenting with stubs this off-season, unfortunately.
2 Likes
I apologize, I had all the info wrong, we actually use Molex SL for CAN, signal, and low power, and we have had 100% reliability for the last 3 years. More info can be found in the below post.
2 Likes
All good, glad to hear you are using better connectors. Also glad to see you guys using the CPA and TPA features.
I’ll leave the post up for anyone that is using “DuPont” style connectors.
We also use wago in part of our can bus connection together with this kind of things, which can make the soft wire harder and wider so that it won’t fall out of the wago connector.
For most places in the can bus, we just solder wires together, which is much more stable.
We used single wago connectors for PDH connections and 5 pole wago connectors for the power of the CTR CanCoders. We didn’t had an issue during the competition but it is useful to check the connections in match breaks. And we had an little issue, the cables of the Spark Max motor controllers sometimes goes out from the wago connectors so we soldered copper 12 gauge cables to tip of the spark max cables and this increased the grip. So I recommend this for increasing the grip in the wago connector.
- SB120 for the battery cables (zip tied over after connected)
- PP45 for most motor wires (zip tied over after connected)
- We’re converting to Molex SL for CAN given vendors are moving in that direction
Your biggest risk in this case is a bad crimp, so if you have good quality control for that then risk of disconnection is manageable.
1 Like
Are you using 4 AWG, or do you have some kind of hack to put 6 AWG into the SB120?
Also, why zip tie the SB120? From our experience, it’s strong enough to hold for much more than a force that could be done on the connector in a match.
You can 3D print something for way less money than that that is functionally equivalent.
There are Anderson branded 1, 2, 4 and 6awg terminals for the SB120 if you know the PN’s.
Then there are reducing bushings to get you to 10awg - and I have used reducing bushings for the SB50 in the 6awg terminals of the sb120 to get reduction down to 16awg? (Don’t have the spec sheet pulled up).
1 Like
I’ve also used the reducing bushes to put a 16 AWG wire in an SB120 (for a battery charger).
3 Likes
4 AWG
We’ve had a few instances where the SB120 doesn’t get fully engaged prior to the match and it comes loose, adding the zip tie and tightening it down is preventative for that.
1 Like
We have found that it isn’t so much that the connectors can’t hold themselves together but the action of a human zip tying the connection is a guaranteed method of insuring that said human properly pushed the connectors together… A forced “triple check” if you will.
This whole mentality stems from, over the years, too many “The battery came disconnected and we don’t know why” statements.
8 Likes
Zip ties are cheap compared to matches.
Never mind the fact we have a cupboard with 20,000 midgrade ties in it…
2 Likes
My team has recently moved to completely Wagos, before we used a combination of Wagos and Anderson connectors.
Imo, Andersons suck, as they’re really annoying to make and can come apart easily if you don’t use like. Quantum theory to find the exact atomic angle the wire needs to be clamped at or hook onto in the connector. Wagos are much easier, and don’t come apart during matches as much!
Also, there have been one too many times where we had to make a quick electrical fix in the pit and replace a wire. You can just take off the Wagos really quickly and reuse them, but the only way to get Andersons off is to cut the wire.
1 Like