Test the Encoders

Discussion in 'Plasmacam Retrofit' started by SignTorch, 4/28/14.

  1. SignTorch

    SignTorch Artist

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    This test is similar to the way we tested the step/dir signals by observing the lights on the servo drive.

    In the previous test we induced a following error by issuing step signals by jogging the axis.

    This time we will turn each motor by hand, which turns the encoder, which also induces a following error, and the lights should progress from IN POS, to WARN, to FAULT the same as it did before.

    With everything turned off, unmount the servo motors, or just take the belt off.

    Power everything on, but don't press reset in Mach3, the servo FAULT light should be on.

    Press the servo reset button, the FAULT light should go off and the IN POS light should come on.

    Now very slowly turn the motor a little bit. The IN POS light should go off and the WARN light should come on.

    Continue turning and the WARN light should go off and the FAULT light should come on at about 46 degrees of rotation.

    Press the servo reset button and the IN POS light comes on.

    Turn the motor very slowly one way just a tiny bit, the WARN light comes on.

    Turn the motor back the other way, very very slowly, and when you get back to the starting position the WARN light goes off and the IN POS light comes back on. It will be tedious to land on the exact starting position by hand like that, but if you're turning slow enough you should at least see IN POS blink on as you go by the starting position.

    That shows you how sensitive the encoder is, it generates 2,000 pulses per revolution, and only one of them is IN POS.

    Each pulse represents .00047 inches of travel, that is the machine resolution. The FAULT light means the position error exceeded .12 inches. That doesn't normally happen in operation. If the WARN light is not on it means the machine position is no more than .00047 inches off, theoretically. That's pretty accurate stuff.
     

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