mycnc:mycnc_pulse_width_setup
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mycnc:mycnc_pulse_width_setup [2019/04/17 14:09] – ivan | mycnc:mycnc_pulse_width_setup [2019/04/24 13:58] – ivan | ||
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====Selecting the Appropriate Pulse Width for your motor==== | ====Selecting the Appropriate Pulse Width for your motor==== | ||
- | A common procedure required for proper motor operation is selecting the appropriate pulse width for the signal going from the controller to the step/servo motor on the CNC machine. As seen in the following instructions from Panasonic' | ||
- | {{:mycnc:pulse-width: | + | A common procedure required for proper motor operation is selecting the appropriate |
- | As another example, | + | As seen in the following instructions from Panasonic' |
- | {{: | + | {{: |
- | A step motor also requires a minimum pulse width, which is considerably higher than that of a servo motor: | + | As another example, the Yaskawa' |
+ | |||
+ | {{: | ||
+ | |||
+ | A step motor also requires a minimum pulse width, which is considerably higher than that of a servo motor (around ten to twenty times higher higher when comparing the specs for the Leadshine step motor below to the Yaskawa servo drive): | ||
{{: | {{: | ||
- | As such, the pulse impulses sent from the controller to the motor have to have a certain minimum width for the motor to pick them up. However, that signal width also cannot be too large due to the signal overlap that would occur otherwise | + | As such, the pulse impulses sent from the controller to the motor have to have a certain minimum width for the motor to be able to register those signals. However, that signal width also cannot be too large due to the signal overlap that would otherwise |
- | **In order to select such an appropriate | + | These constraints on the minimum and the maximum pulse width create a permissible range of pulse widths for each motor depending on its hardware specifications and the particular speeds it is required |
- | *Choose the speed at which your machine will move in **[meters / minute]** | + | ====Pulse Width Calculations==== |
- | *Convert | + | *Choose |
- | *For example, if the desired | + | |
- | *Locate | + | *Convert |
+ | | ||
+ | < | ||
+ | 5 meters/ | ||
+ | 80 millimeters/ | ||
+ | The value for the [revolutions / second] will be equal to 16 revolutions/ | ||
+ | </ | ||
+ | *Locate the minimum **[seconds / step]** value of your step/servo motor (the minimum time it takes the motor to process each individual impulse). This minimum time should be provided in the motor manual. | ||
+ | | ||
*Using the **[revolutions / second]** value and the minimum allowed **[seconds / step]** value of the motor, calculate how many **[steps / revolution]** the stepper driver will have to make. | *Using the **[revolutions / second]** value and the minimum allowed **[seconds / step]** value of the motor, calculate how many **[steps / revolution]** the stepper driver will have to make. | ||
- | *For example, if the minimum allowable | + | *//For example, if the minimum allowable |
+ | < | ||
+ | 1 ÷ (16 revolutions/ | ||
+ | The value for the number of [steps / revolution] will be equal to 7812.5 steps/ | ||
+ | </ | ||
*As discussed earlier, the value selected on the stepper motor must be equal or smaller than the number of **[steps / revolution]** obtained from the previous step for the motor to register the signal and function properly. | *As discussed earlier, the value selected on the stepper motor must be equal or smaller than the number of **[steps / revolution]** obtained from the previous step for the motor to register the signal and function properly. | ||
- | *For example, if the **[steps / revolution]** value has been calculated to be 7800 steps/ | + | *//For example, if the **[steps / revolution]** value has been calculated to be 7812.5 |
*Using the **[revolutions / second]** value and the updated stepper driver **[steps / revolution]** value, calculate the actual **[seconds / step]** value of the motor. This actual **[seconds / step]** value will always be equal or higher than the minimum allowable **[seconds / step]** value of the motor due to selecting a lower **[steps / revolution]** value in the previous steps. | *Using the **[revolutions / second]** value and the updated stepper driver **[steps / revolution]** value, calculate the actual **[seconds / step]** value of the motor. This actual **[seconds / step]** value will always be equal or higher than the minimum allowable **[seconds / step]** value of the motor due to selecting a lower **[steps / revolution]** value in the previous steps. | ||
- | | + | *//For example, if the **[revolutions / second]** value was equal to 16 revolutions/ |
+ | < | ||
+ | 1 ÷ (16 revolutions/ | ||
+ | The value for the [seconds / step] will be equal to 9.76 μs/ | ||
+ | </ | ||
- | *The value for the **Pulse Width** in myCNC software must be equal or higher than the actual **[seconds / step]** value of the motor. | + | *The value for the **Pulse Width** in myCNC software must be set to be equal or to the next closest value that is higher than the actual **[seconds / step]** value of the motor. |
- | *For example, if the **[seconds / step]** value was equal to 9.8 μs/step, and an ET6 or an ET7 board was used, 12 μs would be selected from the chart in the **Common Hardware Settings** tab as it is the closest value that's higher than 9.8 μs. | + | *//For example, if the **[seconds / step]** value was equal to 9.76 μs/step, and an ET6 or an ET7 board was used, 12 μs would be selected from the chart in the **Common Hardware Settings** tab as it is the closest value that's higher than 9.76 μs// |
{{: | {{: | ||
- | *The 12 μs corresponds to Setting 7 in the chart, thus the **Pulse width** value should be set to 7. | + | *The 12 μs corresponds to Setting 7 in the chart, thus the **Pulse width** value should be set to 7 in myCNC software. |
- | | + | *//NOTE: The first value in the **Pulse Width** line refers to the first four axes of the controller (for example, the horizontal X and Y axes), while the second value refers to the other two axes of the controller (for example, the vertical Z axis). These values are set to be different if the controller used on the vertical axis is separate from that used on the horizontal, and are left the same if a single |
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- | *The pulse width setup is now complete. | + | *The pulse width setup is now complete. |
mycnc/mycnc_pulse_width_setup.txt · Last modified: 2024/01/22 11:05 by ivan