Rotary axis scale units 7i77. pid output minimum too large.
26 Oct 2018 15:29 #119453
by PCW
Replied by PCW on topic Rotary axis scale units 7i77. pid output minimum too large.
the ~2 MHZ 7I77 encoder rate is for all channels concurrently (the number of channels has no effect on this ) but does assume perfect 50% duty cycle signal, 1 MHz would
be a better practical limit.
I dont think there will be an issue with the encoder as long as you do not plug it into the system live. I suspect the 9A 0.3 ms ratting just means that the encoder has a fair sized bypass capacitor on the power input so will never get close to 9A unless plugged in live
be a better practical limit.
I dont think there will be an issue with the encoder as long as you do not plug it into the system live. I suspect the 9A 0.3 ms ratting just means that the encoder has a fair sized bypass capacitor on the power input so will never get close to 9A unless plugged in live
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26 Oct 2018 16:20 #119457
by alan_3301
Replied by alan_3301 on topic Rotary axis scale units 7i77. pid output minimum too large.
Thanks for the help. If I should safely get 1Mhz I guess I'm going to hook up the oscilloscope and see what the encoder signals look like. I'm using shielded cat 5 cable for the signals, but I don't think I connected the shield to anything. Maybe that is my problem.
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26 Oct 2018 17:16 #119468
by PCW
Replied by PCW on topic Rotary axis scale units 7i77. pid output minimum too large.
Forgot to mention, you would need to turn off the encoder filter (in the hal file) to get 2 MHz
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26 Oct 2018 17:20 #119469
by alan_3301
Replied by alan_3301 on topic Rotary axis scale units 7i77. pid output minimum too large.
Thank you, I will try that first.
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28 Oct 2018 01:14 #119531
by alan_3301
Replied by alan_3301 on topic Rotary axis scale units 7i77. pid output minimum too large.
Thank you very much. I turned off the filter and now it reads perfectly up to 1500 rpm (1.8M counts / sec)
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