Talon SRX Motor Controller Problem

[Ari423]

Originally Posted by FTC Team CC

Oh ok, that makes sense. Would you recommend using these at all: https://www.amazon.com/Wago-222-415-...AO9N0B7PPXTIQ? Or is it preferable to stick with the two connection options mentioned above?

Regarding the motor controllers, will the CAN connection work even if one of he motor controllers stops receiving power? Does transmission of the CAN signal rely on the motor controllers to be on? Or does the CAN signal get transmitted though the motor controllers even if it does not receive power?

Thanks once again so much.

- Charging Champions

You are better off not using the 5 connectors at all because their only use would be in a star topology which is not the way CAN was designed.

The CAN lines are passed directly through (i.e. input and outputs are soldered together). Unless the wire is cut or the speed controller catches fire and unsolders the wire, the signal will pass through even if the motor controller doesn't get power.

[Ether]

Originally Posted by Ari423

The CAN lines are passed directly through (i.e. input and outputs are soldered together).

Not necessarily disagreeing, but what is your source for this statement?

[Ari423]

Originally Posted by Ether

Not necessarily disagreeing, but what is your source for this statement?

According to page 6 of the Talon SRX User Manual, both CAN wires of the same color are "electrically identical." I would infer that to mean they are physically connected, not just connected by programming. Other people in this thread have also made this claim, but none have provided their source. I imagine someone from Vex or CTRE (or someone who has taken one apart) can give us a definite answer, but I am willing to stick with my inference from the User Manual until someone gives a more definite answer.

[bobbysq]

Originally Posted by Ether

Not necessarily disagreeing, but what is your source for this statement?

Source: Took apart a Talon SRX, looked at the wires, yep they're soldered together. Don't tell inspectors if we ever use a Talon SRX on a robot

[Dwight_2]

Originally Posted by FTC Team CC

We have a problem connecting the motor controller to the PWM ports on the roboRIO. We believe to have correctly connected the motor controller to the roboRIO and the Power Distribution Module. When we connect the motor controller to the CAN port, the motor controller works. However, when we use the PWM ports, the motor controller doesn't work and just blinks red.

We took two photos of the system which are posted below.

Thanks for any help!

My team had the exact opposite happen to our promotional robot (t-Shirt cannon), where the can connection blinked red and the PWM connection worked fine with a slight change in programing.

[ozrien]

Originally Posted by Dwight_2

My team had the exact opposite happen to our promotional robot (t-Shirt cannon), where the can connection blinked red and the PWM connection worked fine with a slight change in programing.

These symptoms sound like simple wiring issues. Students will make mistakes whether you use PWM or CAN bus, (and hopefully will learn from them).

However with PWM you must [1] Wire the devices, [2] Power the devices, [3] Code the devices, and then begin your troubleshooting. With CTRE CAN devices, you can do [1] and [2] only and then begin diagnosing (web-based config, LEDs, Driver Station, etc.).

Additionally the feedback we've received is that CAN bus is far simpler to wire than PWM.

To better answer the questions posed in this thread, I just added some content to the Talon user's guide (pages 35-37).
http://www.ctr-electronics.com/talon...ical_resources

[GeeTwo]

Originally Posted by FTC Team CC

Oh ok, that makes sense. Would you recommend using these at all: https://www.amazon.com/Wago-222-415-...AO9N0B7PPXTIQ? Or is it preferable to stick with the two connection options mentioned above?

Oh, yes we use the multiple-connector WAGO lever nuts for several power applications where we have multiple "custom circuit" loads on a single breaker, and I recommend these for that purpose -- but not for CAN bus.

[FRC Team CC]

Thank you all for the suggestions. We have ordered the CAN connectors sold by CTR electronics.

Thanks,
Charging Champions

[Hitchhiker 42]

Originally Posted by FTC Team CC

Thank you all for the suggestions. We have ordered the CAN connectors sold by CTR electronics.

Thanks,
Charging Champions

Just as an input, for our CAN connections, we use screw terminals.

[b.arci]

Originally Posted by FTC Team CC

Thank you all for the suggestions. We have ordered the CAN connectors sold by CTR electronics.

Thanks,
Charging Champions

We used Marettes (wire nuts) as a temporary connector on our competition robot this past season. Then, we soldered the CAN bus. Although, we used Marettes on our practice bot and never had a problem, and Marettes are a bunch cheaper than those connectors.

[Billfred]

Originally Posted by b.arci

We used Marettes (wire nuts) as a temporary connector on our competition robot this past season. Then, we soldered the CAN bus. Although, we used Marettes on our practice bot and never had a problem, and Marettes are a bunch cheaper than those connectors.

Iron Kings soldered their CAN wires last year as well. I know the SRX is bet-your-season-on-it reliable, but that feels like tempting fate when you have tight match turnarounds. Did you have a plan to replace one in a disaster situation?

While we don't solder our CAN wires, when we have a consolidated control board, we usually wire in an extra motor controller to give us some quick options if one burns up.