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First go with Linux CNC, which Ethernet board?

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  • #16
    The latency of a rpi4 isn't the greatest.. We are talking 70us minimum. It is good pairing to a spi or eithernet external interface card. (mesa)

    If you are going to try to use the pi gpio - you are going to be pretty limited. Talking maybe 10khz step rate.



    Where as a decent computer with a printer port will run 50khz easy.

    Mesa though... So cheap. If you are just looking to get something similar to a smoothstepper a 7i92 gives you 2 printer ports worth of i/o but can be expanded with daughters boards in the future... (though high speed step gen, pwm, encoder counting and i/o)

    https://mesaus.com/product/7i92/

    That you can use the PI to run or a pc... (I am using just the 7i92 to run the green machine - controls everything. (steppers, spindle, spindle encoder, jog wheels and switches, home switches..)

    sam

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    • #17
      Originally posted by skunkworks View Post
      The latency of a rpi4 isn't the greatest.. We are talking 70us minimum. It is good pairing to a spi or eithernet external interface card. (mesa)

      If you are going to try to use the pi gpio - you are going to be pretty limited. Talking maybe 10khz step rate.



      Where as a decent computer with a printer port will run 50khz easy.

      Mesa though... So cheap. If you are just looking to get something similar to a smoothstepper a 7i92 gives you 2 printer ports worth of i/o but can be expanded with daughters boards in the future... (though high speed step gen, pwm, encoder counting and i/o)

      https://mesaus.com/product/7i92/

      That you can use the PI to run or a pc... (I am using just the 7i92 to run the green machine - controls everything. (steppers, spindle, spindle encoder, jog wheels and switches, home switches..)

      sam
      So I can order that 92$ card and run it off the pi with the DB25 to USB cable?

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      • #18
        ? The 7i92 is a realtime Ethernet interface to the computer. It has 2 ports with 17 I/o each. (Out of the box). And expandable.

        I kinda explain it here..



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        • #19
          Ok, I ordered it, sounds like my cheap breakout board plugs into it and can drive the VFD from it. Ok, looks like my intro into LinuxCNC is now set in stone.

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          • #20
            The 7i92 came already, got LinuxCNC 2.8.2 running on the Pi4 4GB. Base thread latency is around 85200, so good enough if using the Mesa board. Power supplies come tomorrow, suppose I could do a bench test with the steppers I have.
            I need to replace the VFD with the DYN4 drive in my mill so I can get that up and running again and I can machine the Taig lathe to receive the ballscrew on Z and mount the steppers. Also need to figure out how to get LinuxCNC to talk to my VFD over RS485.

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            • #21
              Parts are piling up. The lathe bed and carriage is what I bought new. The ER16 headstock was surplus from my Super Taig mill project. Taig makes 3 and 4 jaw chucks that fit the ER16 thread.
              Click image for larger version

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              • #22
                Originally posted by RB211 View Post
                The 7i92 came already, got LinuxCNC 2.8.2 running on the Pi4 4GB. Base thread latency is around 85200, so good enough if using the Mesa board. Power supplies come tomorrow, suppose I could do a bench test with the steppers I have.
                I need to replace the VFD with the DYN4 drive in my mill so I can get that up and running again and I can machine the Taig lathe to receive the ballscrew on Z and mount the steppers. Also need to figure out how to get LinuxCNC to talk to my VFD over RS485.
                What brand VFD is it that you want to run over RS485? There is quite a bit of info and even pre-written code for the Huanyang over RS485, reviewing that may be a good place to start. I have a Huanyang on my bridgeport to run a auxiliary high speed spindle and used the pre-written RS485 driver which worked perfectly with Linuxcnc. I used a cheap USB to RS485 adapter from Amazon.

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                • #23
                  Originally posted by Sparky_NY View Post

                  What brand VFD is it that you want to run over RS485? There is quite a bit of info and even pre-written code for the Huanyang over RS485, reviewing that may be a good place to start. I have a Huanyang on my bridgeport to run a auxiliary high speed spindle and used the pre-written RS485 driver which worked perfectly with Linuxcnc. I used a cheap USB to RS485 adapter from Amazon.
                  It's a TD200 from FactoryMation

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                  • #24
                    Originally posted by RB211 View Post

                    It's a TD200 from FactoryMation
                    Probably not a common enough one to find a pre-written config for linuxcnc but won't be a bad job anyway. With the manual and using the huanyang code as a example I am sure you will whip one up fairly easy.

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