> > I know this goes against the EMC way of doing things but who is going to > want to use a GUI based override when you have a nice convenient knob on > the front panel?
The NIST/EMC way of doing things doesn't just apply to pendant controls vs GUI controls. It is a general principle for any time there can be more than one source of control. For example, a large machine, especially something like a horizontal boring machine, might have two (or more) sets of jogwheels and buttons, one on each side of the table, for the convenience of the operator. If each "operator console" has a feed override knob that is labeled from 0% to 100%, what happens when console 1 is set to 60% and console 2 is set to 20%? The NIST approach is that both consoles should have unlabeled knobs that can spin continuously. If you turn either knob clockwise, the override value increases until it hits 100% (or whatever the upper limit is). After that you can keep turning, but nothing happens. If you turn either knob down, the override goes down, until it hits 0%, then nothing happens. I realize that most machines won't have two control panels, but the general principle is built into the core of EMC2, and I strongly recommend trying to do things that way instead of hacking around it. In this specific case, you have an absolute encoder that generates a number between 0 and 1023. That doesn't mean you need to put a pointer on the knob and draw numbers around it on the control panel - it can still be used as an incremental control. All that is needed is a fairly simple HAL component that accepts the absolute position and converts it to incremental. If the input changes from 100 to 200, the output will increase by 100. An input change from 750 to 700 will make the output will decrease by 50. The only slightly tricky part is when the input wraps. If the input goes from 24 to 1000, there are two possibilities: either it was turned clockwise 976 counts, increasing the count, or counterclockwise by 48 counts, wrapping back to 1023 after passing through zero. Since the counterclockwise case is more likely (you can't turn the knob almost a full revolution in a millisecond), the output would decrease by 48 counts. The HAL component to do this would only require two pins, in and out, and one parameter, the number of counts in one revolution of the input. Its output would always start at zero, and would increase and decrease as you turn the knob. That output could then be used by EMC as if the knob was a regular incremental encoder. It will be at least a few days before I get a chance, but if nobody beats me to it, I'll write that component. Regards, John Kasunich -- John Kasunich [email protected] ------------------------------------------------------------------------------ Download Intel® Parallel Studio Eval Try the new software tools for yourself. Speed compiling, find bugs proactively, and fine-tune applications for parallel performance. See why Intel Parallel Studio got high marks during beta. http://p.sf.net/sfu/intel-sw-dev _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
