What's an Encoder's PPR, CPR, and LPR?
When discussing incremental encoders, the terms CPR, PPR and LPR are often encountered, which stand for "counts per revolution", "pulses per revolution" and "lines per revolution" respectively. These three parameters are used to describe the resolution of the encoder, that is, the number of pulses or lines that the encoder can generate per revolution.
CPR (Counts Per Revolution): Counts per revolution, that is, the number of pulses that the encoder can generate per revolution. This parameter can be used directly to describe the resolution of the encoder
PPR (Pulses Per Revolution): Pulses per revolution, which is the number of pulses that the encoder can generate per revolution. In some cases, PPR and LPR
can be considered equivalent.
LPR (Lines Per Revolution): Lines per revolution, this is a more basic parameter, usually used to describe the number of physical lines on the encoder disc.
Generally in a two-phase incremental encoder, since there are two channels of phase A and phase B, LPR or PPR is usually four times of CPR. This is because at the rising edge and falling edge of each line, and phase A Interleaved with phase B, each line can generate four pulses.
For example: phase A has 2048 pulses/revolution, phase B has 2048 pulses/revolution, the positions of A and B are staggered a little (called a 90-degree phase difference in mathematics), the pulse high is 1, the low is 0, A and B In each pulse cycle, four combinations of 00, 01, 11, and 10 are formed. This is the "4 times frequency", that is, CPR=2048(PPR)x4=8192.
Therefore, generally speaking, for a two-phase incremental encoder, there is the following relationship:
PPR=LPR=4×CPR
However, this relationship may vary depending on the design and operation of the encoder, so in specific applications, it is best to refer to the encoder's data sheet to determine the relationship between these parameters.
CPR (Counts Per Revolution): Counts per revolution, that is, the number of pulses that the encoder can generate per revolution. This parameter can be used directly to describe the resolution of the encoder
PPR (Pulses Per Revolution): Pulses per revolution, which is the number of pulses that the encoder can generate per revolution. In some cases, PPR and LPR
can be considered equivalent.
LPR (Lines Per Revolution): Lines per revolution, this is a more basic parameter, usually used to describe the number of physical lines on the encoder disc.
Generally in a two-phase incremental encoder, since there are two channels of phase A and phase B, LPR or PPR is usually four times of CPR. This is because at the rising edge and falling edge of each line, and phase A Interleaved with phase B, each line can generate four pulses.
For example: phase A has 2048 pulses/revolution, phase B has 2048 pulses/revolution, the positions of A and B are staggered a little (called a 90-degree phase difference in mathematics), the pulse high is 1, the low is 0, A and B In each pulse cycle, four combinations of 00, 01, 11, and 10 are formed. This is the "4 times frequency", that is, CPR=2048(PPR)x4=8192.
Therefore, generally speaking, for a two-phase incremental encoder, there is the following relationship:
PPR=LPR=4×CPR
However, this relationship may vary depending on the design and operation of the encoder, so in specific applications, it is best to refer to the encoder's data sheet to determine the relationship between these parameters.
Updated on: 01/12/2023
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