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Home Forum Configuring LinuxCNC PnCConf Wizard Encoder signals returned to real world

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TOPIC: Encoder signals returned to real world

Encoder signals returned to real world 25 Jan 2012 01:12 #17113

  • Zig
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How to connect

encoder.<chan>.phase-A (bit, In)
encoder.<chan>.phase-B (bit, In)

To a couple of output pins, that is loop the encoder in and out for further processing by external hardware?
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Re:Encoder signals returned to real world 25 Jan 2012 01:50 #17114

  • cmorley
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hmm I don't think this is possible.
There actually isn't encoder phase-A / B HAL signals (unlike software encoder counting)
Since the high speed counting is done on the card, EMC never sees the raw quadrature input.
While you could read the GPIO pins that are related to the encoder they would only be read at the servo thread speed.
So aside from maybe having custom firmware on the card that copies the raw quadrature input to designated output pins
I think your out of luck. Surely Peter from Mesa will speak on this.

Chris M
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Re:Encoder signals returned to real world 25 Jan 2012 08:25 #17127

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Its possible echo the pins out other FPGA pins but I think a better solution is just a Y cable tah send the encoder signals to both places

Is the other device that gets the encoder signals something that can be replaced with a hal component? That might be a cleaner solution
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Re:Encoder signals returned to real world 25 Jan 2012 11:50 #17134

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Its the encoder velocity feedback to the servo amp.

EDIT:

I shall use a longer length of 50 way ribbon cable and crimp 3 connectors. The third last connector will go to a break out board for signal distribution.
Last Edit: 25 Jan 2012 11:55 by Zig.
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Re:Encoder signals returned to real world 25 Jan 2012 11:56 #17135

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OK.
Does the drive have a encoder out? some do
otherwise I would just daisy chain the encoder cable
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Re:Encoder signals returned to real world 26 Jan 2012 12:21 #17172

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The drive does not provide buffered encoder outputs.
I am goimg to use a breakout board ( a 7I42AT ) to access the signal on a ribbon cable with multiple connectors.
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