4.3. Configuring and testing the motor

This section explains how to configure and test your motor over USB using the Jrk G2 Configuration Utility, without using feedback. It is a good idea to test the motor like this to make sure that the motor is working and that you can get the desired performance out of it before you try to set up feedback or a different input mode. Of course, this requires that you have a system that does not destroy itself when run without feedback.

If you have not done so already, you should connect your motor and power supply to the Jrk G2 as described in Section 4.2. Then, connect the Jrk to your computer via USB, open Jrk G2 Configuration Utility, and connect to the Jrk.

If you have changed any of the settings of your Jrk, you should probably reset the Jrk to its default settings by opening the “Device” menu and selecting “Restore default settings”. Then, make sure the “Input mode” is set to “Serial / I²C / USB” (in the “Input” tab) and make sure the “Feedback mode” is set to “None” (in the “Feedback” tab).

The “Motor” tab has several settings that affect the behavior of the motor. For your initial tests, we recommend changing a few of these settings to safe values to help avoid damage:

  • Set the “Max. duty cycle” to a safe value, like 200 (33%).
  • Set the “Max. acceleration” to a safe value, like 6. (It will take 100 PID periods, or 1 second, for the motor to reach a duty cycle of 600 (100%).)
  • For now, you should probably leave the “Max. deceleration” set to its default value of 600 so that the Jrk will always stop the motor immediately when commanded.
  • If there is a “Hard current limit” setting, set it to a safe value, like 3 A. (The Jrk G2 21v3 does not have configurable hardware current limiting so that setting is hidden. Its TB9051FTG motor driver always limits the current to approximately 6.5 A.)

In the “Errors” tab, set the “No power” error to enabled and latched so that your system will stop if there is a power issue and not automatically start running again until you command it to.

You might want to set other limits as necessary. You can read more about the motor settings in Section 7.6.

Click “Apply settings” to apply the new settings to the Jrk.

Click the “Run motor” button to clear any latched errors. The message at the bottom of the Jrk G2 configuration utility should now say “Motor stopped.”. If that message indicates errors instead, you can find out what errors are stopping the motor by looking in the “Errors” tab. You will need to fix those errors before you can test your motor.

You can use the slider in the “Manually set target” box to try out some different duty cycles. The slider controls the “Target” variable, and the Jrk will set the duty cycle to the target minus 2048, after accounting for the limits you have configured. A target of 2048 corresponds to the motor being stopped. One way to set the target to 2048 is to click the “Center” button. You can also stop the motor at any time by clicking the “Stop motor” button.

The green dot on the slider shows the duty cycle (plus 2048). This makes it easy to see if the Jrk’s duty cycle is different from its duty cycle target due to motor limits.

If you have a concept of “forward” for your system but the motor does not go in that direction when you drive it with positive duty cycles, you might want to swap the motor leads or enable the “Invert motor direction” option in the “Motor” tab.

If everything goes well, you should try increasing your “Max. duty cycle”, “Max. accleration”, “Hard current limit”, and other limits in to reasonable values for high-performance operation of your system. If possible, make sure you can get the desired performance out of your motor before setting up feedback.

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