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Software => Software => Topic started by: bubbletea7 on March 01, 2011, 01:37:29 PM

Title: Count vs Cycle for encoder
Post by: bubbletea7 on March 01, 2011, 01:37:29 PM
hello,

What is the different between 1 count and 1 cycle in term of encoder signal?

Because i measure 1 rotation of the motor is equal to the 72 pulse, so, is it 1 cycle is equivalent to 1 count?

Title: Re: Count vs Cycle for encoder
Post by: waltr on March 01, 2011, 02:08:31 PM
Depends on point of view and definitions of the physical system.

Lets say you have an encoder with just one high/low output and its attached to the output shaft of a motor.
As the the motor turns at a constant speed the encode output will be a continuous stream of highs and lows (square wave).

A cycle looking at just the encoder output is from one rising edge to the next rising edge.
If this encoder signal is going into a processor then a count is defined by the processor code. Typically, the 'counter' is incremented on each rising edge. If so then one cycle is also one count.

A cycle could be defined to the mechanical output of the motor shaft so that one rotation is one cycle but this isn't common from the electronics or coding perspective.

Does that help?
Title: Re: Count vs Cycle for encoder
Post by: Billy on March 02, 2011, 03:20:43 PM
What is the different between 1 count and 1 cycle in term of encoder signal?

Typically a "cycle" represents the number of cycles the electronics make per revolution of the encoder, a cycle typically defined by a single line on the encoder wheel passing through the sensor. So if there are 500 lines on the encoder, you will get 500 cycles per revolution.

Counts per revolution depends on counts per cycles. A typical encoder will have 4 counts per cycle. Counts meaning edges in the quadrature 00, 01, 11, 10 sense.  Given a typical 500 line (cycle) encoder wheel, there will be 2000 counts per revolution.

I have worked with encoders where there were thousands of lines in the encoder wheel, with 40 counts per line, so over 100,000 counts per revolution.