Absolute positions typically uses a "bit" principle. Esentally instead of having 4 channels offset 90 degrees from each other. the encoder has X number of sensors that can be on or off. The "X" is the number of bits the encoder outputs.
The easiest way to display this is via a table:
You can see to the Left that based on the Measuring Step a very unique position can be determined by how many and which specific bits are on or off. For instance in the chart to the left, If the poistion (accross the top has a measuring step of 1um Than at a position of 20 um you can see that it would have bits 1, 2, 3, and 17 triggered or activated and bits 4-16 deactivated or not triggered
This allows for greater reliabiablity, and stability on machine tools, and other measuring devices.
The one major benifit to Absolute positioning on a Machine tool is that upon startup the machiner knows its position and if you were in the middle of a project you will not have to back off and re-reference you machine. It will read the machines absolute position upon startup.
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