Dynomotion

Group: DynoMotion Message: 12149 From: cnc_machines Date: 8/25/2015
Subject: 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
Group: DynoMotion Message: 12158 From: Tom Kerekes Date: 8/26/2015
Subject: Re: MUX Encoders
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

Group: DynoMotion Message: 12240 From: cnc_machines Date: 9/10/2015
Subject: Re: MUX Encoders
Got this working. Should have checked the ribbon cable to start with.. would have kept a lot more of my hair that way!