Try disconnecting the 7i77 entirely from the drive and hook a constant voltage source to the drives input - I oftentimes use a 1.5 volt battery ( an isolated voltage source ).
Disconnect the load from the motor so the shaft can turn freely. There should be some instructions for tuning the drive like this as a velocity mode drive. Run the motor in one direction, then reverse the battery to run it in the other direction. See if you can tweak the drive so that it runs smoothly, and at a constant speed. If the drive is not stable using the battery, it will never be stable hooked up to the 7i77. Dave On 3/4/2014 3:35 PM, Marius Liebenberg wrote: > Hi Peter > That is what I did but it seems that no matter how I turn the variable > resistors (multi turn pots) they oscillation remains as strong. There > are some instruction on tuning the drive when using a tacho but nothing > for the encode option. I even tried to remove the feedback to the drive > and go through LCNC for the PID loop. I still cant get rid of the > oscillating feedback > The customer has a set of drives that was supplied by Mesa and I > wondered how you would go about connecting the setup if I had to remove > the drives and replace them with the Mesa drives. I dont know if these > Minibravos are such great drives as I have never encountered them before. > > > On 2014-03-04 21:50, Peter C. Wallace wrote: >> On Tue, 4 Mar 2014, Marius Liebenberg wrote: >> >>> Date: Tue, 04 Mar 2014 21:38:42 +0200 >>> From: Marius Liebenberg <[email protected]> >>> Reply-To: "Enhanced Machine Controller (EMC)" >>> <[email protected]> >>> To: "Enhanced Machine Controller (EMC)" <[email protected]> >>> Subject: [Emc-users] Servo system oscillating feedback >>> >>> I installed a Mesa 5i25 with 7i77 to drive a Minibravo 60 Brushed DC >>> motor drive. It drives a Brushed DC motor (ESA 3M 8019) from Motor Power >>> Company. There is a encoder fitted to the motor. Also an ESA 3Mxx? There >>> is a 10:1 planetary gearbox fitted to the shaft. >>> >>> The Minibravo's are designed to work with a tacho and has a tunable PID >>> interface when using the tacho. These drives are fitted with an encoder >>> interface board that turns the pulses into an analog voltage that is >>> supposed to be representative of the rpm of the motor. When the encoder >>> option is used it seems that the PID is not in circuit. >>> >>> The problem is that I get a constant severe oscillation when the motor >>> is in rest as well as when it is driven. When I scope it with Halscope, >>> I see the constant ripple on the feedback count as well. If I remove the >>> analog input signal to the drive, I still get the oscillation. >>> >>> Has anyone have any experience with this kind of setup. Your assistance >>> will be appreciated :) >>> >>> -- >>> >>> Regards /Groete >>> >>> Marius D. Liebenberg >>> +27 82 698 3251 >>> +27 12 743 6064 >>> >> I would expect that there is a PI velocity control loop in the drive that >> takes the simulated tachometer signal as the velocity feedback. >> >> If the driver/motor oscillates without any feedback from LinuxCNC you will >> need to lower the drives P/I gains until it is stable before proceeding. >> >> >> >> >> >> Peter Wallace >> Mesa Electronics >> >> (\__/) >> (='.'=) This is Bunny. Copy and paste bunny into your >> (")_(") signature to help him gain world domination. >> >> >> ------------------------------------------------------------------------------ >> Subversion Kills Productivity. Get off Subversion & Make the Move to >> Perforce. >> With Perforce, you get hassle-free workflows. Merge that actually works. >> Faster operations. Version large binaries. Built-in WAN optimization and the >> freedom to use Git, Perforce or both. Make the move to Perforce. >> http://pubads.g.doubleclick.net/gampad/clk?id=122218951&iu=/4140/ostg.clktrk >> _______________________________________________ >> Emc-users mailing list >> [email protected] >> https://lists.sourceforge.net/lists/listinfo/emc-users >> ------------------------------------------------------------------------------ Subversion Kills Productivity. Get off Subversion & Make the Move to Perforce. With Perforce, you get hassle-free workflows. Merge that actually works. Faster operations. Version large binaries. Built-in WAN optimization and the freedom to use Git, Perforce or both. Make the move to Perforce. http://pubads.g.doubleclick.net/gampad/clk?id=122218951&iu=/4140/ostg.clktrk _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
