Troubles with Talon SRX in Follower mode

[jfitz0807]

I have 4 Talon SRXs controlling 4 CIMs on the KoP chassis drive train. CAN ID 1 is front left, 2 is back left, 3 is front right and 4 is back right. I set both 2 and 4 to follow 1 and 3, respectively. In this configuration, it looks like 2 and 4 have stopped driving. The red and green lights no longer light up when driving.

Also, when running the Talon self test from the roboRIO configuration window with the robot enabled, Talons 2 and 4 do not report any current. Similarly, GetCurrent returns values of zero.

Is this expected behavior for a Talon in follower mode? If not, any suggestions?

[ozrien]

Did you update the firmware? See Talon SRX Software reference manual

[ozrien]

So what are the the LEDs doing? Solid orange? Did you follow the examples in the software ref manual?

[jfitz0807]

I followed the examples. The lights are not doing anything.

[ozrien]

By not doing anything do you mean both LEDs are off as though the Talon is not powered? If so double check your wiring with a voltmeter. Also check if the breaker is in place on the PDP. If they both look ok contact support@crosstheroadelectronics.com.

[jfitz0807]

The lights are actually solid orange. We put a voltmeter on one of the follower Talons and read 26mV; ie, nothing.

[ozrien]

So that means the Talons are being command to zero throttle. Either the mode is not correct or it's following the wrong Talon or the Master Talon isn't present on the bus.

If you use the self-test you can check the mode of the followers to confirm they are in slave follower mode. (section 2.4 in Talon SRX software reference manual).

Double check the Set() calls to your slave Talons. Remember the Set() is used to specify the master Talon ID. (section 9 in Talon SRX software reference manual).

[jfitz0807]

The self test shows that the talons are in follower mode. When I run the self test with the motors running, the lead talons show a non-zero current value, but the following talons show 0 current.

Here is the code we are using to set the talon:

driveSubsystemMotorControllerBackLeft->SetControlMode(CANSpeedController::kFollower);
driveSubsystemMotorControllerBackLeft->Set(3);

driveSubsystemMotorControllerBackLeft is Talon 4.

If I understand correctly, this should set Talon 4 to follow Talon 3. We have similar code for Talon 2 to follow Talon 1.

Am I doing something wrong?

[ozrien]

Yeah that looks right to me. The only thing I can think of is if the firmware is old. Did you update to 1.1 or 1.4?

[RufflesRidge]

How are you commanding the "lead" Talons?

[jfitz0807]

Talons were updated to 1.1.

The lead Talons are being commanded via ArcadeDrive. They are in ControlMode kPercentVbus=0. When Talons 2 and 4 are set to this mode, they behave correctly (lights go red or green depending on direction, current reads non-zero in Self Test while driving). It's only when they are set to ControlMode kFollower=5 that the lights stay orange and no current is read.

Thanks for all the suggestions.

My next plan is to move the Talon breakouts from Talons 1 and 3 to Talons 2 and 4, respectively and then make them the lead Talons and set 1 and 3 to followers just to see if anything is different.

I'm running out of ideas and we really need to get this to work.

[RufflesRidge]

Are you passing just the two lead motors to the Arcade drive or all 4?

[ozrien]

Can you post the source? Or send it to support@crosstheroadelectronics.com

[jfitz0807]

Our RobotDrive is using the 4 motor constructor. Should we just change it to the 2 motor constructor?

[RufflesRidge]

Originally Posted by jfitz0807

Our RobotDrive is using the 4 motor constructor. Should we just change it to the 2 motor constructor?

Yes, the RobotDrive object is calling Set on your follower Talons with a value from -1 to 1 which is causing your issue.