Full reverse on jags problematical

[jmiller18]

We have tried 8 jags, 2× 4jags, across 2 crios both on the v47 image, and when we do full reverse voltage on all 4 jags on either crio, the jags to disconnect.

I thought it had to do with too much load with all 4 full reverse, but when we saw it happen on the second with 4 diffrent jags, 2 new and just out of the box, we started thinking it has to do with the image.

has anyone else had similar problems and or a solution?

[ehochstein]

I am assuming that the lights flash red when they "disconnect".

I would suggest switching to a victor or a talon and testing it before ruling it an image problem.

Most likely the Jag is reseting due to how much current it is pulling. It is a safety measure.

[slijin]

Are you controlling the Jaguars via CAN or PWM?
Can you describe the behavior of their LEDs when you reverse the control signal? (I assume this is what you mean when you say "reverse voltage" - if you're actually reversing the polarity of the Jaguars' power supplies, well...)
Please explain what you mean by "disconnect" - do you lose communication with them temporarily, do they stop responding to changes in input, etc?

If you have a large load on these 8 Jagaurs, Wiifi is most likely correct in saying that by suddenly reversing the control signal, you're forcing a current fault condition (Jaguar firmware is written to temporarily cut control when current exceeds 40A; if this is what is happening, the status LEDs will slowly flash red and yellow for ~3s). The easiest way to rectify this problem is to enable automatic current ramping (see p11-12 here).

[Joe Ross]

How is the digital sidecar wired?

[jmiller18]

We are using pwm, when we using testing mode and slowly send more and more negative control signals to each jag one at a time, the jags will eventually stop and blink their led's as if the pwm was disconnected but will return to normal operation when we disable and re-enable.

Also, when we do all 4, the breakers don't trip

[Kevin Sevcik]

Do you have the 12V power connector on the digital sidecar connected to set of 12V terminals on your power distribution board? Your sidecar needs external power to generate signals. If you have it connected properly, all three LEDs should be lit up green.

[ehochstein]

Originally Posted by jmiller18

We are using pwm, when we using testing mode and slowly send more and more negative control signals to each jag one at a time, the jags will eventually stop and blink their led's as if the pwm was disconnected but will return to normal operation when we disable and re-enable.

Also, when we do all 4, the breakers don't trip

What color are they blinking? Are you 100% certain it is yellow?

[Alan Anderson]

Originally Posted by jmiller18

We are using pwm, when we using testing mode and slowly send more and more negative control signals to each jag one at a time, the jags will eventually stop and blink their led's as if the pwm was disconnected but will return to normal operation when we disable and re-enable.

This is a clear symptom of not having the Digital Sidecar properly powered. It should have 12 volt battery power connected from a 20 amp breaker on the Power Distribution Board, and all three of the power LEDs on the Digital Sidecar should be lit.

[slijin]

Originally Posted by jmiller18

We are using pwm, when we using testing mode and slowly send more and more negative control signals to each jag one at a time, the jags will eventually stop and blink their led's as if the pwm was disconnected but will return to normal operation when we disable and re-enable.

When you incur this fault condition, is disabling and re-enabling the only way to re-establish communication? That is, after incurring the fault, can you re-establish communication by sending a neutral or full forward command to the Jaguar without disabling and re-enabling?

Originally Posted by jmiller18

Also, when we do all 4, the breakers don't trip

What do you mean by this? Are you implying that incurring the fault condition on just one Jaguar trips its breaker, but incurring it all four does nothing? I'm not really sure what you mean. If this was in response to this, though:

Originally Posted by slijin

If you have a large load on these 8 Jagaurs ... you're forcing a current fault condition (Jaguar firmware is written to temporarily cut control when current exceeds 40A; if this is what is happening, the status LEDs will slowly flash red and yellow for ~3s).

then I believe you are misunderstanding what a "current fault condition" is. The 40A breaker will not automatically reset immediately trip when current exceeds 40A. Moreover, there is no physical circuit breaker in the Jaguar; rather, when the Jaguar's internal sensor detects that the current being drawn is exceeding 40A, the Jaguar's firmware will respond by incurring a current fault condition by cutting control for 3 seconds and flashing the status LED red and yellow.

[Kevin Sevcik]

Originally Posted by slijin

then I believe you are misunderstanding what a "current fault condition" is. The 40A breaker will not automatically reset when current exceeds 40A

Slijin,
We're using auto-resetting SnapAction breakers in FRC. They actually DO reset after a few seconds. The only breaker that wouldn't reset after you tripped it is the main 120A breaker. Assuming you actually really tripped it and didn't just jostle the contacts loose.

[jmiller18]

Originally Posted by slijin

When you incur this fault condition, is disabling and re-enabling the only way to re-establish communication? That is, after incurring the fault, can you re-establish communication by sending a neutral or full forward command to the Jaguar without disabling and re-enabling?



What do you mean by this? Are you implying that incurring the fault condition on just one Jaguar trips its breaker, but incurring it all four does nothing? I'm not really sure what you mean. If this was in response to this, though:



then I believe you are misunderstanding what a "current fault condition" is. The 40A breaker will not automatically reset when current exceeds 40A. Moreover, there is no physical circuit breaker in the Jaguar; rather, when the Jaguar's internal sensor detects that the current being drawn is exceeding 40A, the Jaguar's firmware will respond by incurring a current fault condition by cutting control for 3 seconds and flashing the status LED red and yellow.

1)Have not tried that, will try at the next meeting on Monday and i will post the results.

2)If i were to do give a negative signal to the jags one by one, then i can hear/see the red light indicating the 40 amp breakers tripped, but if i were to send all 4 full reverse, then hear nor see the red light so the power board isnt tripping

[slijin]

Originally Posted by Kevin Sevcik

Slijin,
We're using auto-resetting SnapAction breakers in FRC. They actually DO reset after a few seconds. The only breaker that wouldn't reset after you tripped it is the main 120A breaker. Assuming you actually really tripped it and didn't just jostle the contacts loose.

Thanks for pointing that out; I meant to say that they don't immediately trip, whereas Jaguars do.

Originally Posted by jmiller18

If i were to do give a negative signal to the jags one by one, then i can hear/see the red light indicating the 40 amp breakers tripped, but if i were to send all 4 full reverse, then hear nor see the red light so the power board isnt tripping

Well now... I had originally suspected that your Jaguars had been mis-calibrated (with regards to this, can you confirm whether or not the LEDs flash yellow when you "disconnect"?), but this is a whole new can of worms.

More questions:
When you cause an individual Jaguar to fault, is the breaker that trips the one that corresponds to the Jaguar you're faulting?
Have you tried testing what happens if you fault exactly 2 or 3 Jaguars simultaneously, instead of all 4? If so, what happened? If not, please try testing every combination of 2 and 3 Jaguars that you can and record the results.

Also, can you answer Joe's and Kevin's question about your DSC wiring setup - that is, is the 12v power supply to the DSC properly connected?

If you could upload a detailed picture(s) of your wiring configuration, or possibly even a video of the condition when you get back to school, that would be helpful too.