>-----Original Message----- >From: Kirk Wallace [mailto:[email protected]] >Sent: Wednesday, March 16, 2011 3:35 PM >To: Enhanced Machine Controller (EMC) >Subject: Re: [Emc-users] Spindle speed control through G540 VFD output > >On Wed, 2011-03-16 at 21:05 +0000, andy pugh wrote: >> On 16 March 2011 20:50, Michael Jones <[email protected]> >wrote: >> >> > And yes, the pot is isolated as you've said. >> > >> > Does this mean that this upgrade is a "not recommended" or possibly >> > hazardous direction, or just that there's more I need to do besides just >> > hooking up the VFD output pins from the G540 to make it work >> > correctly/safely without breaking something? >> >> It should be fine, but you need to know how "isolated" the VFD output is. >> I had a KBIC speed controller and the low side of the pot was held at >> +Motor voltage (100V) >> The VFD output has it's own GND terminal, which is a good sign. >> >> http://www.cnczone.com/forums/gecko_drives/88165- >g540_vfd_output_floating.html >> Has a comment from Mariss (who is Mr Gecko) saying that it will be OK. >> > >"The analog output is optically isolated from both the G540 and the PC. >- Mariss" > >This quote doesn't instill much confidence, but it seems that the G540 >terminals 7 Ground, 8 Output, 9 +10V are isolated from the Gecko circuit >and float. I am guessing these terminals are implying a potentiometer >like function in the G540. The +10V terminal is were you would connect >the +10V output from the KBIC to a potentiometer. Ground connects to the >ground from KBIC potentiometer terminal for the far end of the >potentiometer from the +10V. Then the output terminal (8) and an EMC2 >digital PWM signal go to the potentiometer wiper. > >Current >KBIC >--------------- >GND Wiper +10 > | | | > | V | > +-----------+ > Potentiometer > >New >KBIC >--------------- >GND Wiper +10 >| | | >| | | >GND OutP +10V > 7 8 9 > G540 > ^ > | >Parport 14 > >The wiper will be controlled by the EMC2 PWM on parallel port pin 14 VFD >PMW (50Hz). See here for the EMC2 HAL setup: >http://linuxcnc.org/docs/html/examples_spindle.html#r1_2 > >The PWM frequency will be determined by the thread rate that the PWM >component is loaded in - usually the servo thread or 1kHz (?). The G540 >doc hints at 50Hz, but I think it will work anyway. This is off the top >of my head, so check the above for yourself. > >I suspect you could wire the terminals directly, but there is a >possibility that current limit resistors might be needed somewhere. >--
I went back and looked compared my wiring to the above text diagram from Kirk and found I had things wired pin 7 and 9 reversed - fortunately I didn't fry the G540 because of it. Thanks Kirk for the clue!!! Michael ------------------------------------------------------------------------------ Enable your software for Intel(R) Active Management Technology to meet the growing manageability and security demands of your customers. Businesses are taking advantage of Intel(R) vPro (TM) technology - will your software be a part of the solution? Download the Intel(R) Manageability Checker today! http://p.sf.net/sfu/intel-dev2devmar _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
