Re: [Help] Problems with Encoders and PID Control
 

Your concern is warranted. As it is we won't pass inspection.

The LED's on our PDP are blinking amber even when the robot is enabled. The team says they've never been anything different. That would have included our first tournament.

I did do a close look for debris. We have been very diligent about debris and chaff this year.

We are out of time now.

Re: [Help] Problems with Encoders and PID Control
 

No sarcasm at all intended, but was it also that way when you first did the benchtop checkout of the control system in early January?

Re: [Help] Problems with Encoders and PID Control
 

That is what is called a sticky fault and just indicates that sometime in the past the battery voltage dropped below the brownout cutoff.

It stays amber through power cycles until you explicitly clear the fault using the roboRIO WebDash.

Re: [Help] Problems with Encoders and PID Control
 

Sarcasm is deserved as I was stubborn on the voltage check. But what has happened is largely due to being a rookie to the new tech. (We had signed up for the beta program but didn't make it, so there's that). I had been thinking of deleting my posts due to sheer embarrassment, but it is a learning experience and has at least that merit.


From what I've researched it looks like we clear the sticky fault by doing a self test. I will do that at my next opportunity.

My question is, once this is done, will it clear up the problem (assuming it no longer exists). In other words, could everything be ok now but we are still in this condition because we haven't done the clear sticky fault?

Re: [Help] Problems with Encoders and PID Control
 

As far as the sticky fault in the PDP, that's just for your diagnostics. If you clear it and then notice it get set again, that just means your PDP saw <6.5 V since the last time you cleared it. That doesn't affect your robot behavior in any way, it's just a trouble code for your sake.

As far as the encoder, did you actually confirm that it wasn't getting power due to the roborio-power-fault (which has nothing to do with the PDP sticky fault)?

Re: [Help] Problems with Encoders and PID Control
 

The amber status lights on the PDP aren't really a problem, they are just information.
If you clear them to green again, then you can check them after each match to see if you had any brownouts.

Re: [Help] Problems with Encoders and PID Control
 

I assume your encoder is intended to be powered from that pin. That would definitely explain why you're not getting the results you want.

What power light are you referring to? What do you mean by "normal"? The Power LED on the roboRIO ought to be green. It turns red if there is a problem with one of the power buses -- for example, the DIO power pins.

That is consistent with something shorting the DIO power bus to ground. The DIO signal pins have a resistor to 3.3 volts. There are two things to check immediately: look for debris in the roboRIO connectors (and remove it if found), and make sure nothing connected to the DIO pins is inappropriately connecting power to ground.

Re: [Help] Problems with Encoders and PID Control
 

In the end the roboRio was deemed defective by NI, another one was sent to us, then this one was returned.

Much help was provided by the CSA at our last regional event. We opened the roboRio and found a lot of chaff inside. It was mostly Delron plastic shavings, but it showed us how much chaff can get inside and it was a lot. We should probably have considered some sort of housing for the roboRio, however in this case it was not the problem.

The CSA then initiated an RMA with NI while at the event Though we could have done this ourselves, we highly appreciated the help.

Since we could find no visible shorts between the pins, there was nothing else we could do. NI concurred hence the RMA.

A more fortunate ending would have been to find an actual pin short. In this case we would have expected the power light to change from red to green upon eliminating the short.