On Sat, 2008-08-09 at 22:34 -0400, Jim Coleman wrote: > Tonight I hooked up the jogwheel and one of the motor's encoders (100 > line and 2500 lines) to the parport, and with turning up the ferror in > the ini I can use it like a DRO, turning the encoders moves the axis > readings. I was wondering if i could just build an H bridge or > similar switching circuit to run the output between the -12 and +12V > rails on an AT or AT power supply, maybe use 7809 and 7909 regulators > to keep it below 10V, to run to the analog VCMD input on the servo > amp? the manual to the mill says that it runs +/- 9V, which seems odd > compared to everything else. Then I'll have to likely put in a couple > switches on the a and b's of the encoders to send the quadrature to > both the amp and back to EMC. If I managed my math right, if i can > get the parport sampling at 30 khz (i think i read somewhere that that > should be realistic) I should be able to keep track of 180 RPM or so > on the encoders, if everything stays ideal.
It sounds like you want to go directly from a jog wheel to a motor driver for axis movement. Then have EMC as a DRO. If that is the case, why not have EMC2 do the motion control and do manual machining with the jog wheel through EMC2? This is the normal setup. The hardware would be the same except you wouldn't need to build an encoder to motor drive interface. This could be tricky because the jog wheel is a position device and the amp input is a velocity signal. One unit change on the jog wheel doesn't correspond to a particular amp signal. I would look into setting up EMC2 to have a two parallel port pins for PWM Forward and PWM Reverse. Each of these could feed an opto-coupler that would switch your +9 or -9 Volts to convert them to a PWM modulated analog signal for your amp input. I am not sure of the details, and there might be vastly better ways to do this, but this is just to convey an idea of how EMC2 could output a voltage (velocity) that your amps need and have EMC2 do the position thing from the encoder feedback. > Also, what do I need to add in the hal and everything to enable an > index on the encoders? I'm thinking I can see if it is missing counts > if I have an index to reference. I think you would need to write a custom component that reads the software decoder counter on the first index trigger and then compares that with subsequent counts on index to see if they happen on multiples of encoder counts per rev. I wouldn't mind seeing more background error checking of hardware subsystems. > I hope all of this makes sense, its been a long day and I'm excited > I've actually made a little progress. > > Thanks guys, > Jim Coleman Are you doing more than one project? I thought you where well along on a mill conversion. Could you give us a summary of what you are doing? -- Kirk Wallace (California, USA http://www.wallacecompany.com/machine_shop/ Hardinge HNC/EMC CNC lathe, Bridgeport mill conversion, doing XY now, Zubal lathe conversion pending Craftsman AA 109 restoration Shizuoka ST-N/EMC CNC) ------------------------------------------------------------------------- This SF.Net email is sponsored by the Moblin Your Move Developer's challenge Build the coolest Linux based applications with Moblin SDK & win great prizes Grand prize is a trip for two to an Open Source event anywhere in the world http://moblin-contest.org/redirect.php?banner_id=100&url=/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
