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MUX Encoders

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  • cnc_machines
    Tom, I have a couple of questions and hope that you can help. I am trying to input encoders into JP7 and JP4. Can I simply delete ENC_4_7_JP6 from the
    Message 1 of 3 , Aug 25, 2015

      Tom,


      I have a couple of questions and hope that you can help. I am trying to input encoders into JP7 and JP4.

      1. Can I simply delete "ENC_4_7_JP6" from the program - this would allow me to keep my encoders on JP7? The reason for keeping the input on JP7 is because the encoder is being input from a third party servo driver - I am assuming it would drive over 3.3V and would damage JP4.
      2. Which pins on JP4 have the "A" and "B" channels? It looks like the first available IO pins on JP4 are 6&7 (IO16 & 1017). I have attempted to do this but get no input on the step response screen.

      Reference MUX program:

       // Mux encoder inputs from KFLOP JP7 & JP5 to JP4 and JP6

      FPGAW(ENC_NOISE_FILTER_ADD) = ENC_0_3_JP4 + ENC_4_7_JP6 + ENC_NOISE_FILTER_DEFAULT_VAL;


      Thanks,


      Scott

    • Tom Kerekes
      Hi Scott, Regarding: #1 - that is correct.  KFLOP JP4 and JP6 are 3.3V Inputs and will be damaged if hard driven above 3.8V.  Most 5V TTL outputs don t do
      Message 2 of 3 , Aug 26, 2015
        Hi Scott,

        Regarding:

        #1 - that is correct.  KFLOP JP4 and JP6 are 3.3V Inputs and will be damaged if hard driven above 3.8V.  Most 5V TTL outputs don't do this as they are only required to drive to 2.8V or higher.  I have never heard of this being a problem.  If you have doubts you might check it with a voltmeter and a 150ohm termination (pull down resistor).  The 150ohm termination resistors on KFLOP JP4 and JP6 work well to avoid signal ringing.  If you use KFLOP JP7 you might want to add those externally.

        #2 - The first 8 Inputs on JP4 are Encoders 0-3 A/B signals (when mux'ed).  The first 8 Inputs on JP6 are Encoders 4-7 A/B signals (when mux'ed).  I don't know why there isn't any change on the Step Response Screen.  Do the corresponding Inputs on the Digital I/O Screen toggle when the encoder moves?  Which I/O pins toggle?  What Input Channel is the Axis Channel configured for?

        Regards
        TK


        From: "cnc_machines@... [DynoMotion]" <DynoMotion@yahoogroups.com>
        To: DynoMotion@yahoogroups.com
        Sent: Tuesday, August 25, 2015 3:08 PM
        Subject: [DynoMotion] MUX Encoders

         
        Tom,

        I have a couple of questions and hope that you can help. I am trying to input encoders into JP7 and JP4.
        1. Can I simply delete "ENC_4_7_JP6" from the program - this would allow me to keep my encoders on JP7? The reason for keeping the input on JP7 is because the encoder is being input from a third party servo driver - I am assuming it would drive over 3.3V and would damage JP4.
        2. Which pins on JP4 have the "A" and "B" channels? It looks like the first available IO pins on JP4 are 6&7 (IO16 & 1017). I have attempted to do this but get no input on the step response screen.
        Reference MUX program:
         // Mux encoder inputs from KFLOP JP7 & JP5 to JP4 and JP6
        FPGAW(ENC_NOISE_FILTER_ADD) = ENC_0_3_JP4 + ENC_4_7_JP6 + ENC_NOISE_FILTER_DEFAULT_VAL;

        Thanks,

        Scott


      • cnc_machines
        Got this working. Should have checked the ribbon cable to start with.. would have kept a lot more of my hair that way!
        Message 3 of 3 , Sep 10, 2015
          Got this working. Should have checked the ribbon cable to start with.. would have kept a lot more of my hair that way!
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