cmparker Posted February 5, 2013 Share Posted February 5, 2013 I have a Geo Brick LV connected to an external amplifier through the pulse/direction outputs on a encoder connector. I tuned the external amplifier for the motor and can command it to move (using the external amp software). Is there a guide I can follow for how to setup the Delta Tau to work with the amplifier? Also, how does tuning in this configuration differ from tuning a motor directly connected to the Delta Tau? Link to comment Share on other sites More sharing options...
steve.milici Posted February 7, 2013 Share Posted February 7, 2013 Refer to the section "Step and Direction PFM Output (To External Stepper Amplifier)" in the "Geo Brick LV User Manual" starting on page 49. There you will find the complete hardware and software setup details. Link to comment Share on other sites More sharing options...
cmparker Posted February 8, 2013 Author Share Posted February 8, 2013 Refer to the section "Step and Direction PFM Output (To External Stepper Amplifier)" in the "Geo Brick LV User Manual" starting on page 49. There you will find the complete hardware and software setup details. Thanks for pointing me to the right place! I was able to follow the example and get a motor moving on axis 8. I am now having trouble getting the Delta Tau to use the real encoders and not just "phantom closed loop" control. Here is my setup: I7140=8 (Servo IC 1 Channel 4 Encoder/Timer Decode Control = Internal pulse and direction) i811=3200000 (Fatal Following Error Limit: 1/16 Counts) i822=300 (Jog Speed: cts/msec) i830=699 (PID Proportional Gain) The encoder is 8000 cts/rev I attached a txt file with the other I vars. When I issue a j+ command I see a following error of ~14cts at 300kcts/sec. The motor accelerates smoothly up to speed and maintains it nicely. Now when I change I7140 to 3 (x4 quadrature decode CW) I have problems. The motor will start spinning, then start oscillating, then the external amp will shut off. It seems the PID loop of the Delta Tau and the PID of the external amplifier are causing the oscillations. I found if I decrease the gain (I830) to 75, then I can get the motor moving with a following error of ~130000cts at 300kcts/sec. What should I do to maintain a low following error without causing the oscillations?Closed Loop Example.txt Link to comment Share on other sites More sharing options...
steve.milici Posted February 8, 2013 Share Posted February 8, 2013 When you use an encoder on a Turbo PMAC2 PFM stepper setup you will tune the motor/encoder as a velocity loop servo. You can use our tuning program to do this. The “Auto-Tune” feature may also be used. Make sure to set it for velocity loop (radio button). Link to comment Share on other sites More sharing options...
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