Quote:
Originally Posted by Al Skierkiewicz
M,
There isn't a rule that specifies connectors for the CAN bus but I have to ask "why"? This is a critical part of the robot and should be treated a such. For that reason I highly recommend as few connections as possible. If you are going to use the APP connectors, be sure to use the 15 amp terminals and if your wire is very small gauge, I recommend you strip twice the length needed and fold over the exposed wire before inserting. This will give you a more reliable crimp. Don't forget the need to terminate the bus.
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The CAN bus connections are critical just like many others such as the power to the RoboRio. Since the CAN bus wires are integral with the Talon SRX, teams who use a crimp to join two of them together will have to cut the wires when re-using the motor controllers, making the wires shorter each time. The wires can be soldered and then un-soldered but soldering has it's own problems. This is where teams have to learn to do a good job and learn to enforce an adequate level of Quality Control (treat them like one would treat the braking system in ones car).
The CAN Bus wires are much smaller than the wires normally used with the Anderson connectors. They may have to be folded over more than two times for the crimp to hold the wire in properly. If not done right, the wire may pop out with a slight pull later. I am also concerned with the relatively high un-mating force of the Andersons. Many people pull on the wires to un-mate connectors even though that is bad practice. With the 14-10 AWG wire normally used, the wire and crimp have a decent chance of staying together. With the small CAN wires, I can foresee people breaking the wires.
Quote:
Originally Posted by dellagd
We're planning on using some crimp connectors to just crimp the wires together once we have all of the Talons mounted. Minimizes the probability of failure and we're not too concerned with having to cut the wires when were done, saying as we'll only be doing it a few times a year in a worst case scenario. |
We just started using them at work and got them from Home Depot or Lowes until our regular wholesale suppliers got them in stock for us.
Quote:
Originally Posted by DonRotolo
CAN really doesn't like connectors, but the Talons seem to require some sort of solution. Powerpoles are overkill and provide a relatively large impedance 'bump'; I';d recommend 0.100 headers like those used for PWM connections.
Whatever solution you choose, make SURE that CAN Polarity is absolutely correct, or you'll be unhappy with robot performance.
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Some fairly expensive equipment or some very specialized 3-D field-solver software would be needed to determine, objectively, the effect of a connector on the CAN Bus impedance. In general, a connector with contacts that have dimensions and physical configuration most similar to the rest of the transmission line (the wires) will probably introduce the least disturbance to the impedance and the least corruption of the signal. Thus, the locking connectors from Hansen, or something like them, are probably the best solution. An added bonus is that the "Latching Male Housings" from Hansen seem to have a shroud so that when male pins are inserted into them, they cannot short to anything unless one pokes something into the end.
http://www.hansenhobbies.com/product.../pt1in_lp_1x3/