Hi all, I have a strange problem which looks like it is related to the position feedback, but I also suspect I may be looking in entirely the wrong place. I have a three axis configuration where the Z axis is mapped to a PWM for a laser. The hardware is the Mesa m5i20 controller with the hostmot2 firmware. Z is directly fed to the laser, the feedback settings are just to prevent following errors. I have tried several ways of connecting the Z command and position feedback, but this is the way that so far works the best (X and Y are shown just for completeness):
net Xpos-cmd axis.0.motor-pos-cmd => hm2_5i20.0.stepgen.00.position-cmd net Ypos-cmd axis.1.motor-pos-cmd => hm2_5i20.0.stepgen.01.position-cmd net Zpos-cmd axis.2.motor-pos-cmd => axis.2.motor-pos-fb net Xpos-fb hm2_5i20.0.stepgen.00.position-fb => axis.0.motor-pos-fb net Ypos-fb hm2_5i20.0.stepgen.01.position-fb => axis.1.motor-pos-fb net Zpos-cmd => hm2_5i20.0.pwmgen.00.value setp hm2_5i20.0.stepgen.00.position-scale [AXIS_0]SCALE setp hm2_5i20.0.stepgen.01.position-scale [AXIS_1]SCALE setp hm2_5i20.0.pwmgen.00.scale 1.0 Now here is the strange part, if scale in the last line is set to 1.0, everything seems to work fine (except as below). If scale is set to something less that 1.0 it runs gcode for some length of time until the system e-stops, but no error message is generated. The length of time (number of lines of gcode) is dependent on several factors, among them: 1> Increasing FERROR (in the ini file) causes it to run longer to a point. 2> Decreasing scale decreases the amount of time before e-stop 3> Increasing the period of the servo thread increases how long the gcode runs before encountering an estop, at least to a point. 3> Changing the axis type from linear to angular usually increases the number of lines of g-code executed, however when scale is 1.0 only angular eventually results in the error, if it would occur with the axis as linear, I do not have a g-code file long enough (3000+ lines) to encounter it. For example, FERROR of 10.0, servo period of 1000000, and scale of 0.1 will execute about 1000 lines of my test program. Decreasing scale to 0.01 decreases the number of lines executed to about 200. I am directly feeding the commanded position back to the feedback position, so I do not see how scale can affect the feedback loop, or really anything else. It isn't connected to anything except the PWM output itself. The scale in the ini file is set to 1.0, and directly set in the hal file. It may be something else entirely, but I do not see it. I checked for an over temp condition on the laser for example, because as scale decreases, laser power increases, but it is not faulting, and would only shut down the laser if it did. As a stepper system, basically everything runs open loop, so there really aren't any conditions which would cause it to shut down. I have another box, which I can upgrade to the same version of Linux and EMC, and see if it generates the same error when completely disconnected from the hardware. I just need to force the NC limit switches. Any other ideas or speculations appreciated. Regards, Eric ------------------------------------------------------------------------------ SF.Net email is Sponsored by MIX09, March 18-20, 2009 in Las Vegas, Nevada. The future of the web can't happen without you. Join us at MIX09 to help pave the way to the Next Web now. Learn more and register at http://ad.doubleclick.net/clk;208669438;13503038;i?http://2009.visitmix.com/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
