I am doing electrical for my team this year for the second year in a row and I am not great at cable management. I was wondering if anyone had pictures of their electrical boards from past years or cad/step files of them. Also if anyone has part recommendations for connecting like CAN wires or any other wires that would be much appreciated! Thank you!
There are a number of alternatives for connecting CAN wires discussed recently at https://www.chiefdelphi.com/forums/showthread.php?threadid=181959.
Google is your friend…
frc electronics board images
Post a picture of your electrical board last year, and we might be able to give you suggestions how to improve this year.
Our boards generally are laid out with power flow to the drive motors as a high priority–short wire lengths for that. Accessibility is also a high priority, we need to be able to get to stuff, especially the RoboRio and PDP. Unfortunately, we always seem to end up putting smaller wires on top of everything, as we add sensors, etc. If you plan for these wires ahead of time, you should do ok.
Another thing is that the size, shape, and location of our electrical board is different every year, because the robot has to play a different game every year. We do our best to plan the robot overall design in a way that lets us put the electrical components in a place that is relatively safe, accessible, and close to things that it controls, to reduce wiring lengths. It’s always a compromise, though.
So 2 years ago 1745 started a project to make a better electrical system (we lost like 3 or 4 matches that year because of electrical problems)
here was our initial requirements
- Vertical so any debris fall through the board not on the board
- Done in CAD so the design team has to remember the electronics
- Easily accessible with out removing any sub systems
- Everything has marked a place, and everything in one place.
- Cut outs for wires.
- 1’x2’ total size, because that’s the bed size of our laser cutter.
- Vertical again.
last year we did this
https://cad.onshape.com/documents/4b53ca4e10587a2519a2e699/w/ce471528428b83ec26a35550/e/dac1fe0416c895a5c0429258
And it worked out pretty well. only had 1 electrical issue and that was with a motor wiring.
After the season we added a few more changes we wanted to see
- a back plane to for tie downs, wire routing, and stiffness.
- A cover with a cut out for the power switch
- Pneumatics included on panel
- Better labeling
and this was the revised version we are going to start with for this year (note the shape and layout may/will change once the game is revealed)
https://cad.onshape.com/documents/a011a7d3d6da81b1d6cbe2ab/w/058380bd0f0b1319b67fc940/e/c775486e4dacd9eb40788841
I would actually say that the second part is not necessarily good advise. It’s HOW you ziptie/attach/harness your wires that can make replacing wires/components either really easy or really a pain. Ziptieing wires together could–to some extent–make replacing easy.
For example, if you grab a bunch of wires and ziptie them really tightly to the nearest frame member every two inches, sure, that’ll cause lots of issues. But if you ziptie the wires in pairs (each red/black pair together) and at larger intervals ziptie the entire harness to ziptie attachment points stuck onto the same frame member, it’ll be a lot easier.
I would suggest using spiral wrap–it’ll keep all the wires together, but still allow you to pull individual lines out where you want them to go. Then tie the bundle down at loose intervals.
But if you ziptie the wires in pairs (each red/black pair together) and at larger intervals ziptie the entire harness to ziptie attachment points stuck onto the same frame member, it’ll be a lot easier.
We are going to use “zip-cord” / 2-conductor wire / speaker wire this year to try to make things neater. https://static.dxengineering.com/global/images/prod/mediumlarge/DXE-PW-10_ml.jpg
I haven’t seen many teams use this. I’m not sure why.
We have used it for many years. We stock 10, 12, 14, 18. It is available through MCM electronics, West Mountain Radio and even Amazon. However, be careful in checking the description, some sources do not use cable reels.
Cheaper cable will pull insulation off the wires when you “zip” the two conductors apart.
I’m probably going to get some hate for this since I can’t seem to convince people this actually works, but for CAN management, we actually don’t Daisy-Chain our cables like most teams do. Instead we use only one set of wires from each CAN device (we typically spool up the extra wire so it’s there as a backup), add Anderson connectors to the CAN wires, then connect all the devices to one of these distribution blocks (Green to black, and Yellow to Red). This effectively creates a “Bus” topology (contrary to popular belief, it is NOT a “Star” topology), making it much easier to organize CAN wires and adds redundancy to the system, since if one of the cables comes disconnected somehow, the rest of the system still works (as long as the cable that comes off isn’t the one going to the PDP or the RoboRIO). This layout has worked flawlessly for the 4 seasons I’ve done it.
At some point, I’d like to replace the distribution blocks with custom PCBs with Weidmuller connectors to save weight and space.
My team swears by this stuff. Very nice way to keep pairs of wire together and organized. We get ours from PowerWerx (apparently they’re also on Amazon now)
Some good practices:
Wire labels.
Labels help with troubleshooting later on should a problem ever arise.
Label Motors, Label motor controllers, label sensors…
For CAN wires, use the Weidmueller Ferrules and Ferrule tool.
Strain Relief your wires.
Be aware that PWM wire can be easily pinched and smoked.
If connecting PWM to PWM, use a small piece of EE tape to hold the connectors together.
Whenever possible place electronics so they are easily visible. This again can help with diagnostics.
I heavily recommend using Anderson connectors. They are great for connections in robots.
As far as routing goes, have spare wire and take an afternoon re-wiring to get things to lay nice and have reasonable paths.
That’s reasonable; though I will say that that is not what I picked up from your initial post.
Inspectors LOVE neat, accessible wiring. Makes tracing the wires much easier. (Also… labels or color-coding. Not for the inspector, for the team.)
We used WAGO Splicing connectors for CAN wires. It was a major help in keeping the electronics organized and made the neatest wiring we’ve ever had. I highly recommend!
With respect this is not good advice. Bundling the wires together and tying them down makes your robot more robust, a lot more robust. There is a reason professional wiring harnesses look the way they do. The robot is a high vibration environment and you should NOT leave wires going everywhere and not secured to a fixed point.
For more general advice …
We do not prioritize the placement of all the electronics on a single board. You need to plan for the location of the roboRio, the PDP, the battery and the main breaker but other components can go in convenient locations. It is a very good idea to minimize the length of power runs to the motors (that consume a lot of current) and especially from the battery to the PDP. Run wires orthogonally (so not diagonally across open spaces), preferably alongside some structural piece of your robot. If possible use wire ties every six inches and everywhere wire(s) enter and exit the bundle. Secure the wires close to the end points to minimize the effect of vibration on the endpoints (strain relief). Use the correct tools and test (physically and electrically) EVERY connection. Wire labels are a big help, especially in quick turn repair scenarios at competition.
Doing a good job wiring the robot is important for the reliability of your machine. Nothing is more frustrating than spending 6+ weeks on the robot and it failing because of one loose wire. But other teams also look at your wiring job. Many elite teams will not pick a robot that looks like a mess - it is just too risky.
There’s a happy medium. A team could use a centralized electrical panel with cable ducts and minimal zipties to have a clean panel with easily traceable and replaceable components and cables. Add cable clips and organizers, and you can further reduce zipties. I agree though that zipties on exposed wire bundles are best.
I think this also comes down to team preference and there isn’t a universal best practice. For some teams, the most reliable electrical system will be fully centralized, with short CAN/PWM cables, easily checked blinkenlights in one place for troubleshooting, and reduced connections by wiring motor controllers directly into the PDP. It can also solve some electrical/mechanical fighting for robot access if most wiring can be done off-bot, then a single board is mounted. I agree though that once you can really trust your design and wire routing, the freedom to put some components anywhere is a great option.
It does not have to look nice but label your for example our motors are organized motor 1,2,3,4 then the wire at both end of the connection say for motor 1 the wires going to that motor are labeled M1 with sticker wrapped abound the wire. I works very well and if you need to replace something you know what wires go to that motor. Hope this helps.
Zip ties and masking tape labels are your best friend. Label all of your cables at each end. Having the shortest length of cable possible from point A to point B isn’t always the best for organization; in fact it often isn’t. Route like cables together when possible (ex. drive motors w/ other drive motors). Think of your final product like someone’s penmanship, we all know when someone’s writing looks sloppy, but we also know that neat writing comes in many variations.
- Use zip-cord
- Zip tie everything, zip tie every few inches
- Run wire in straight lines and 90 degree turns (with a sensible radius) instead of wacky wavy curves
- I’ve never used labels and I’ve never missed them
- Same for ferrules
*]Pull-testing every connection you make is more important than any aesthetic factor
This x100
My team uses them and they make things alot more organized.
I’m curious about this. Can you explain more about how the topology works?
Thanks,
- Antonio