Jaguar communication issue

[kenavt]

Originally Posted by jhellr13

For a drivetrain code, whatever the drive code (arcade, tank. holonomic) is placed in the begin vi. On that block, the pwm cables are assigned for each jaguar controlling the CIM motors. In teleop, that is where you initiate the drive system and make it controllable by a joystick. As a heads up, if you are doing omni wheel or mecanum, remember that those drive systems have 3 axis. Forward, back, and strafe.
If you need some help because it seems like you might be confused, check out this link. It is the team website for Mark McLeod's team up above. They have a great resource for LabVIEW programming on any topic and it was a great help for me this year, and certainly help you out right now.
http://team358.org/files/programming...2009-/LabVIEW/

Frankly, I've never seen anyone place drive code in the Begin.vi - it was my understanding that was for initializing PWM channels, not putting drive code in Robot Main.vi at that point. You may be talking about the Open 4 Motor.vi, which frankly shouldn't be neccessary - I can open individual motors just as easily.

I may seem confused because I believe that I am initializing PWM channels correctly for each individual motor, but nothing seems to be allocated. That website is a great resource, though. I'll be sure to look through that.

[Mark McLeod]

If you set the motor output in more than one place, especially in someplace like Periodic Tasks, then it could be overriding your Teleop Motor Set and keeping PWM2 in neutral.

I assume the rest of Teleop has a simple straight-through dataflow, without loops or delays.

You might try a step-by-step troubleshooting approach.

1. Create a new project from scratch
2. Don't change the existing code, leave the default drive motors, code in Disable, etc.
3. Add just your new Jaguar out on an unused PWM with a new joystick control.
4. See if that works.
5. Step-by-step begin to remove the default code, and changing the code over to resemble what you are having trouble with now.
6. Test at each change, e.g, 1) just remove the old drive motors, 2) test, 3) relocate your single Jag to PWM2, 4) test, 5) remove the code throwing errors in Disable, 6) test, and so on.

[Alan Anderson]

Originally Posted by kenavt

Frankly, I've never seen anyone place drive code in the Begin.vi - it was my understanding that was for initializing PWM channels, not putting drive code in Robot Main.vi at that point. You may be talking about the Open 4 Motor.vi, which frankly shouldn't be neccessary - I can open individual motors just as easily.

If you're going to be using the provided tank, arcade, or omni drive functions, you need to define the drivebase motors using an Open 4 Motor (or Open 2 Motor) function. Opening the motors individually is a little more work, and if they are opened individually then controlling them appropriately is even more work.

I may seem confused because I believe that I am initializing PWM channels correctly for each individual motor, but nothing seems to be allocated.

You haven't shown us the rest of your code, so we can't do much to help you debug it. You also haven't indicated whether or not you've done any troubleshooting, either by "probing" the value going to the Motor Set or by swapping wires around to see if the problem stays with the Digital Sidecar's PWM output or with the Jaguar.

[sithmonkey13]

Check the connection between the PWM cable and the Jaguar. We have had problems with this before, and as a result, we always hot glue the cables to the Jaguars, as driving in a match could shake the PWM cables loose.

[jhellr13]

Originally Posted by sithmonkey13

Check the connection between the PWM cable and the Jaguar. We have had problems with this before, and as a result, we always hot glue the cables to the Jaguars, as driving in a match could shake the PWM cables loose.

We also hot glue the pwm cables. This year we even made a lexan casing that went around the electronic part of our robot. Because it was clear, the refs and everybody could see our electronics, but the tubes couldn't get stuck in the cables. The casing had a hole for the light, and a slit where the power switch was available. We put velcro around it, so it easily came on and off.

[kenavt]

I've had a busy last week(two robotics demos, the offseason MARC competition), but I tried the code with a different cRIO, Digital Sidecar, and Jaguars. I had the same result happen where the PWM channel seemed to be allocated incorrectly, so I talked through my drive code with a recently graduated programmer. We isolated the issue to a wrongly attached wire, automatically sending null commands to the Jaguar. So, that was the issue after all.

Thanks a lot for the help anyway. I've learned a bit about debugging, and hopefully I'll be able to bring this knowledge forward into my next project, next build season, and beyond.