andyf Posted October 5, 2011 Share Posted October 5, 2011 What is the accuracy of the clock in the PPMAC board in PPM? Link to comment Share on other sites More sharing options...
curtwilson Posted October 6, 2011 Share Posted October 6, 2011 The clock on the Power PMAC CPU board has a listed tolerance of 50ppm. However, it is the clock crsytal on the ACC-24E board that is the source of the system servo and phase clocks that determines the time accuracy of trajectory motion. The tolerance for these is 100ppm on the ACC-24E2x boards, and 50ppm on the newer ACC-24E3 board. Link to comment Share on other sites More sharing options...
andyf Posted October 6, 2011 Author Share Posted October 6, 2011 Do you offer any upgrades to the PPMAC CPU board clock? Link to comment Share on other sites More sharing options...
curtwilson Posted October 7, 2011 Share Posted October 7, 2011 No we do not. Most of the people who cannot tolerate 50ppm cannot tolerate, say, 20ppm either. Those who need very high time accuracy for trajectory motion, which includes many observatory users, feed in a very accurate clock into a spare encoder channel and set up the motion to use "external time base". But that involves the clocks on the axis boards, not the CPU. What do you need higher time accuracy on the CPU for? Link to comment Share on other sites More sharing options...
andyf Posted October 7, 2011 Author Share Posted October 7, 2011 I think your suggestion of external time base is what I'm looking for. See my other post "Execute move every n triggers" Link to comment Share on other sites More sharing options...
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