Inability to set a wrap for 45 degree motion

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Joined: Tue May 10, 2016 4:48 pm

Inability to set a wrap for 45 degree motion

Postby om_tech_support_JS » Mon Jan 30, 2017 12:19 pm

Q: I am using the DG200R-ARAAD package for my bottle filling application. The rotary actuator needs to rotate 45 degrees for the next bottle to be filled. I want to use a wrap setting so that the next empty bottle becomes the 'zero' location. This way, if any issue occurs, I can go back to the zero location and not have to worry about which bottles have been filled or not. My issue, however, is that I set the wrap setting range to 2250 pulses (18,000 pulses per revolution / 8 stopping positions = 2250 pulses for a 45 degree rotation) and I am getting an alarm 72h for Wrap Setting Error. What am I doing wrong?

A: The wrap function of the DG series (also found in the AR series and AZ series stepper motors), resets the command position to zero when the wrap setting range is exceeded. In the "Wrap function" section of the manual, you will see a table for the wrap setting as well as two equations for the setting condition of the wrap function. Both of which are depicted below:

Wrap Function.png
Wrap Function.png (188.6 KiB) Viewed 353 times

In order for a wrap setting range to be accepted, it must satisfy the equations for Condition 1 and Condition 2.
In your setting example, the Electronic gear A and Electronic gear B are both set to 1 (default settings).

Therefore, for Condition 1: (1000/50) = 20 which is an Integer meaning that Condition 1 is met.
However, for Condition 2: 2250 *(50/1000) = 112.5 which is not an integer. Condition 2 is not met, so an alarm 72h is generated.

Unfortunately, 45 degrees is not an accepted wrap location. Furthermore, attempting to change the resolution by changing the gear ratios did not result in meeting the conditions either. Since the same number would have to be multiplied to the pulses as was divided to get the resolution, the equation will result in the same 112.5 value.

Instead, you can use a "P-Preset" input after every completed move. The P-Preset input changes the current position value to be whatever is stored in the P-Preset value. Factory Default for the P-Preset is 0. Therefore, when the move has been completed, you can turn on the P-Preset input and the new location will become the zero location.

If the P-Preset option is not an option that can be considered, then 90 degrees would be the closest and easiest wrap location for your application. If you use 90 degrees, then the wrap setting range would be 4500 pulses. If you use 4500 pulses, then the conditions will be met.
Condition 1: (1000/50) = 20 which is an integer
Condition 2: 4500 *(50/1000) = 225 which is also an integer.

Since you still require the 45 degree positions, you can set an Area Output to be for the 2250 pulses. In creating this area, you can see if the area output is on or not. If the area output is on, then you need to go back to the 2250 position, otherwise, you can go to the 4500 position if the area output has not turned on.

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