Is it FRC legal to use connectors like the XT-60 or XT-90 ? We would be using it to have a quick disconnect between cims and ESC’s. Also thinking about using xt-30’s for CAN bus connections? Let me know if any of this is legal.
Any connector is legal as long as it’s rated for the breaker amperage. XT60’s are rated for 60A continuous, so you should be fine. Be sure to provide literature proving this in case your inspector asks.
I personally recommend Anderson Power Poles. Easy to crimp, no soldering required, and color-coded.
It’s legal to use quick-disconnects for CAN connections. I’ve used PWM housings/pins in the past. XT30’s may be a better option though- less chance of coming apart or de-crimping.
*As with all rules, they only apply to the previous season. You will have to refer to the 2018 manual to verify legality for the 2018 season.
Corresponding rule for 2017:
Source: https://firstfrc.blob.core.windows.net/frc2017/Manual/Sections/08-Robot.pdf
All are legal if they are rated for the amperage. Biggest disclaimer is rules may change next year, but historically the electrical ones have not in this regard.
The XT series are decent, biggest calvaet is you have to have a good soldering iron and the technique to do it quickly without melting the plastic. While with powerpoles you just crimp which I find as reliable and easier to teach (with the proper tool).
+1 to above. Since at least 2012 (I haven’t dug back farther in the rules), the only mandated electrical connectors have been the battery connector and connectors to interface with the required or exclusive control system items, and the limitations/prohibitions have been based on current and voltage ratings.
That said: While they are legal, let me urge you away from XT-30’s or any other 30A or even 15A rated connector for the CAN bus. The N in CAN is for network, meaning that the wire is a wave guide for transmittal of digital information. Any impedance mismatches, whether a bad connection or a 30A connector on a 20+ AWG wire, will reflect signals, generating network noise. With digital networks experiencing noise and multipath (reflections), things will typically work great or at least passably until they fail catastrophically. Why take that chance? I strongly recommend using connectors designed for passing signals over 20-28 AWG wire, such as RJ-11, RJ-45, VEX’s CAN connectors, or Molex ditto.
Of these, 3946 uses VEX’s CAN connectors, because it simplifies compliance with tournament COTS rules in recent years because it requires neither crimping nor soldering. (For 2017, see particularly R15 and the difference between the exceptions to R21 vs R13, particularly the fact that R13d is not included in R21. That is, you can put a COTS device with connectors on your robot before bagging even if they were done in a previous year, but after bagging, the connector(s) must be crimped/soldered/clamped added at an event or during an authorized open bag period.)
Seconded. We tried using Anderson Powerpoles on all our CAN connections a couple years ago, and had a bunch of trouble with Talons randomly dropping out. Decided to solder all the connections that year eventually.
On my team we use XT-60’s and XtT-90’s for all of our motor connections and Molex connectors for 5v and signal wires, but it is necessary to have a locking housing in order to prevent failures.
Have you had issues with them coming apart in matches?
Anderson connectors aren’t designed for such thin gauge wire. They’re not a drop in do-it-all solution for FRC wiring, and it pains me to see people using Andersons for things like CAN wires or solenoid wires like this.
I too know this pain.
I finally gave up on connectors for CAN. We solder those wires together and apply heat shrink. I was recently introduced to these though and now have a supply on hand for emergency splicing of CAN wires: http://a.co/72yKVgt
I wouldn’t use them unless needed. It’s better to solder the CAN wires from our experience.
We use the Molex SL interconnects and crimp the connectors. Works great for all low-voltage applications on the robot. If we’re concerned that one might come apart, we use a small piece of electrical tape for retention.
If you’re going to use modular (RJ-11 or RJ-45) connectors, be sure to specify stranded wire.
There are plenty of valid, robust connectors for small gauge wiring. They’re just often prohibitively expensive, or annoying, or not robust etc etc etc.
If you wanted extremely expensive overkill, Deutsch DTM series connectors would be a very excessively robust way to wire these, for example.
For what we do, it’s hard to beat soldering / crimp-splicing / heat shrinking; it’s not like we’re rewiring CAN buses regularly, and they’re cheap / compact / robust enough.
We never had any issues with the XT-60 connectors this year, especially after having numerous issues with Andersons the year before. (likely from buying lower quality connectors, but the XT-60 connectors are cheaper than even the cheap Andersons)
We use the regular PWM connector on the CAN talon. (On the PWM Talons as well, but that is different story) tape the connector together. We get our from Hansen hobbies.
We have never had any issues, if we are concerned with one pulling out we secure a zip-tie around the connector, for instance on our climber this year we designed it so that the motor-winch assembly could be taken apart from the robot in order to remove the rope. The XT-90 that powered that motor was secured with a zip-tie.
https://drive.google.com/file/d/0B8YxdItx9sobVXROenhqckN6VWM/view?usp=sharing
I’ve had good success using Wago 221 style connectors for CAN wires, they come in suitable sizes for the small gauge CAN wiring. They are a lever-style crimpless connector. The option of two or three wires per connection allows more flexibility in daisy chaining your CAN bus as well. They lasted all of last season without any coming off. They can be had from 25 to 75 cents each, so they’re not the cheapest solution, but I think they make up for that with the ease of use, and not having to solder.
221-413 for three positions
221-412 for two positions
Our team used the XT-60 connectors last year, and it was fantastic. The only downside is that they need to be soldered, but aside from that, we never had one connector come apart, or become sloppy from unplugging/plugging in too many times. I would highly recommend them.
Edited to add: We purchased ours through Buddy RC.
I got a few samples from Wago of these and was super impressed. Huge wire gauge range and it felt super solid in the clamp. Pretty much impossible to screw up too, which isn’t true for anything requiring crimping. They’re smaller than the pictures make them seem too. 1072 may try using these for 2018.