REV Hardware Client - can't run motors

On our new robot, my plan was to test our motors using the REV Hardware Client. However I’m not having any luck getting the “Run Motor” option to do anything.

My setup is:

  • RoboRIO has the latest firmware
  • 6 Spark Max Controllers are installed
  • Several Talon SRXs are installed. All motor controllers are on the CAN Bus
  • I have a USB-C cable connected between the laptop and one of the spark max controllers
  • The REV Hardware Client sees all the motor controllers.
  • Each Spark Max has a unique CAN ID (1,3,4,5,8 and 9)
  • Each Spark Max has firmware version 1.5.2 (the latest version)
  • I’m running Ver 1.1.0 of the Hardware Client
  • All spark max’s are slow blinking magenta

I can click on each spark max in the client and click on the “identify” icon and see the fast flash on the correct controller.
But if I click on the Run tab and choose a speed and click Run Motor, nothing happens.

I had this working at one time but we had some mechanical problems. Now that the mechanical problems are fixed, I can no longer run any motors from the client.

One thing that might be related - I deployed software to the RIO. It’s possible that when I first used the client successfully there was no valid software in the RIO (i.e. it was just after doing a firmware update).

What am I missing here? There’s gotta be a reason why I can’t run motors from the client.

You cannot have the RIO in the CAN network with the controllers if you want to control if via the Hardware Client.


Thanks. Being a strictly software sort of person, it’s not obvious to me how to get the Rio out of the chain. Are there any simple solutions to this? I’m guessing that removing the CAN wires from the Rio won’t work?

That will absolutely work.

Another option would be to unplug the Rio from the power. That way the bus termination resistor is still present.

Sometimes pulling the 10A fuse is easiest.

The will work. But. Breaking the fuse holder has been a common failure mode. That might have been just with the early models, and I am superstitious.

No luck so far. I have tried the following:

Remove power from the Rio.
None of the devices show up on the list in the client. Obviously for our configuration, the Rio must be powered.

Restore power to the Rio
Remove one of the CAN bus wires from the Rio
Now the devices show up but still can’t run any of the motors.

Reformat the Rio so there’s no software in it
Reattach Rio CAN bus wires and power up
All devices shown on list (Rio isn’t listed)
Can’t run any of the motors.

I’ve seen this work once! But unfortunately can’t recall what I did to make it work.

I must be missing something!

Try this sequence:

  • Remove power to the Robot
  • Remove both of the CAN bus wires from the Rio
  • Power the robot back up
  • See if the Client works

If you power the RIO while it’s connected to the CAN network at any time, then the Spark Max’s will remember it was once there and you won’t ever be able to control them using the Client.


Thank you. I finally got it to work. We also discovered some CAN bus wiring problems along the way so perhaps it was multiple problems. But now that it’s wired correctly, your solution works! Thank you very much for your prompt response.

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