7i77 individual analog enable

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22 Jan 2019 09:20 #124604 by Juckix
Hello,
I am working on a retrofit of a CNC mill and was wondering if the analog enable channels (optocouplers) on the 7i77 can be toggled individually. I'd like to use it as a way to combat idle oscillation of the axis servos. In the original setup the servos were quiet when at standstil which I assume was done by disabling the servos individually when they reached the desired position. Each axis has its own enable signal.

Thanks for any help.

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22 Jan 2019 09:47 #124605 by PCW
Replied by PCW on topic 7i77 individual analog enable
The lower 5 analog enables on the 7I77 cannot be driven individually,
though you could perhaps use field outputs for this function.

However, Its very unlikely any system that disables servos while active will work
very well since the drives enable/disable time will cause serious instabilities with any dynamic load. Oscillation when idle is typically a tuning issue, either with PID terms or if its a very small (+-1 encoder count) dither, setting an appropriate deadzone value.

Other, more sophisticated (than simply adding deadzone) tuning options include
using PID terms that are velocity dependent, so the static tuning is optimized for lack of dither

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