Hubert, The term PWM as discussed here is referring to the signal from the parallel port to the device used to set the motor speed. In the case of the X2 and many other DC motor drivers, the current supply into the motor is also controlled by PWM, but it is generated and controlled by the motor driver speed control circuits, not directly by the parallel port. The "gain" that Gene referred to is the ability of the motor driver to regulate the motor speed under varying mechanical loads. The motor driver senses the motor back EMF while the PWM drive is turned off and uses that as a feedback signal representing the actual motor speed. There is a small pot within the drive to adjust the "gain" on this feedback and thus the stiffness of the speed regulation control loop.
The G540 speed control output is isolated already. I am not sure if the X2 violates the 12 volt maximum control voltage imposed by the G540. The signals you need will be obtained by removing the wires from the pot in the X2 and connecting them as follows: Pos 7 VFD GROUND from X2 pot counterclockwise terminal Pos 8 VFD OUTPUT from X2 pot wiper terminal Pos 9 VFD +10VDC from X2 pot clockwise terminal You can check the X2 control voltage by measuring carefully across the pot with power applied. Remember that these signals are floating at line voltage!! You will also need to provide a relay to replace the switch on the back of the pot. The Output-1 and Output-2 terminals on the G540 can drive a suitable relay, but the relay will require a power source for its coil because the G540 provides only a transistor switch to ground. The X2 motor control is a little unusual. You cannot just switch the AC mains coming into it to start and stop the motor. The switch on the back of the pot must also cycle. Additionally, the motor driver should not be started at speed, it must be ramped up from zero or you will blow fuses. The ramping can be done with HAL. Lastly, if you require reversing, a large DPDT relay will be needed to swap the motor leads. This relay can be switched ONLY when the motor is fully stopped. Before you start rewiring, I recommend carefully documenting the connections inside your X2 motor control box. It is easy to assume that you can remember where the wires go, but then find that you had too many things going on and forget. Regards, Steve Stallings www.PMDX.com > -----Original Message----- > From: Hubert Bahr [mailto:h...@hbahr.org] > Sent: Saturday, October 10, 2009 3:26 AM > To: Enhanced Machine Controller (EMC) > Subject: Re: [Emc-users] Spindle Control > > Gene > When you say micromill are you referring to the X2. I have > one of these as well. I am running it with EMC2 though the > parallel port with a G540 driver. It accepts a VFD PWM signal > and has an op-isolated 0 to 10 volt analog output for a VFD. > It also has 2 uncommitted output pins. It looks like I could > take the VFD PWM signals in parallel to feed the PMDX-106 or > I may not need it if the VFD output will work for the mill > motor controller. So how did you hook up the VSD to the PMDX. > From a quick review of the PMDX-106 manual you can use the > pot to set the speed through the PMDX but it uses an analog > voltage out to set the VSD speed. > You certainly seem to have put me on the right track. It > looks like I need to break out the meter and read the values > across the pot. It is starting to look like the G540 already > almost everything I need except for the relays and signal > conditioning for a sync signal. Reviewing the StepConf > portion of the getting started guide makes me believe I have > a chance for a first order solution in its spindle control > section. Down stream I may want to achieve a more robust > solution with something like the Mesa cards. > > Jon > Warning noted. It looks like my driver may have already > considered that and provides an optical isolated output and > uses a PWM input. > > Thanks > Hubert ------------------------------------------------------------------------------ Come build with us! The BlackBerry(R) Developer Conference in SF, CA is the only developer event you need to attend this year. Jumpstart your developing skills, take BlackBerry mobile applications to market and stay ahead of the curve. Join us from November 9 - 12, 2009. Register now! http://p.sf.net/sfu/devconference _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
