Duet FSR's Stuck at Min Stop

dkaustin
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Duet FSR's Stuck at Min Stop

Postby dkaustin » Tue Jul 11, 2017 6:03 pm

My Max V2 with Duet and FSR's is out of commission because the FSR probe is stuck at min stop. Probing is unsuccessful and generates an error message: "Z probe already triggered at start of probing move." Tapping the bed above each FSR lights the corresponding LED on the FSR board. Lifting the bed off the FSR's does not clear the problem. It's not a wiring problem. Disconnecting the FSR board from the Duet does not clear the problem.

Is it a firmware glitch? Nothing in the config file has changed. Nothing in the hardware has changed.

I am well and truly stumped.

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DeltaCon
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Re: Duet FSR's Stuck at Min Stop

Postby DeltaCon » Wed Jul 12, 2017 4:03 am

Does that also happen with the FSR sensors disconnected? (finger on the off-switch!)
Perhaps a sensor can be defective?
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dkaustin
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Re: Duet FSR's Stuck at Min Stop

Postby dkaustin » Wed Jul 12, 2017 11:22 am

Disconnecting the FSR's (one at a time or all at once) doesn't affect the behavior. On G32, the head moves to each of the probing points and stops about 5mm above the bed; it then immediately moves to the next probing point because it thinks the probe is triggered. When the routine completes, the head returns to home and an error message is generated: "Z probe was already triggered at start of probing move."

If I invert the probe signal with M558 I1 the G32 probing routine runs normally, but the probe never triggers, even though the LEDs on the FSR control board light each time the head contacts the bed.

I have tried fiddling with the threshold parameter in M558 and can get M119 to report that the probe is no longer stopped, but that doesn't affect the problem.

One thing I am NOT seeing is the Endstop LED on the Duet board responding to activation of the FSRs. Is my Duet board kaput?

dc42
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Re: Duet FSR's Stuck at Min Stop

Postby dc42 » Wed Jul 12, 2017 1:05 pm

I suspect that you have a bad crimp connection in the output wire from the FSR board to the Duet. You can test the Duet's input by disconnecting the FSR board and shorting the two outer pins of that endstop connector together. The LED should come on and the firmware should indicate that the Z probe state has changed.

dkaustin
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Re: Duet FSR's Stuck at Min Stop

Postby dkaustin » Wed Jul 12, 2017 4:13 pm

Well blow me down, dc42! That was it! I am in your debt, sir.

(I think crimp connector is an oxymoron.)


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