Application of absolute coding

Comparison of absolute coding incremental coding

The incremental encoder outputs a certain number of equally spaced pulses (PPR) each time it rotates one revolution produces a linear motion of one inch millimeter. For applications motion direction detection is important, a single-channel output is usually used. For applications that require direction detection, a quadrature signal output with a 90-degree phase deviation between the two channels will be used; the circuit determines the direction of movement according to the phase relationship between the output signals. This method is suitable for applications that reverse motion need to maintain a fixed position when stationary mechanically vibrating. For example, the vibration that occurs when the machine stops can cause a one-way encoder to produce a series of pulses, which the controller may mistakenly regard as motion. If a quadrature encoder is used, the controller will have such errors.

When higher resolution is required, the counter can simultaneously count the rising falling edges of the pulse sequence one channel, so that it can output twice (x2) the number of pulses per revolution per inch. Calculating the rising falling edges of the two channels can get 4 times the resolution.

The output of the incremental encoder is used to indicate movement. It determines the position by accumulating the number of pulses by the counter. This count is easily lost when the circuit transients cause power outages voltage fluctuations. Each time the system starts, the device also returns to the reference original position to initialize the position counter.

Some incremental encoders can also generate another signal called "marker", "index" "Z channel". This signal is generated once per revolution in the shaft encoder, once when it encounters an accurate known point in the linear code scale. It is usually used to determine the location of a feature, especially in the homing process.

The absolute encoder generates a digital code that represents the actual position of the encoder its speed direction of movement. If there is a power failure, after the power supply is restored, its output is correct, there is no need to return to the reference position like an incremental encoder. Only short-circuit data will be generated. This error usually lasts for a short time is enough to affect the dynamic performance of the control system.

The resolution of an absolute encoder is determined by the number of bits of its output word. This output can be standard binary code Gray code, the latter only produces a 1-bit change in each step to reduce errors. The difference between an incremental encoder an absolute encoder is like a stopwatch a clock.

The stopwatch measures the incremental time start to end, which is like an incremental encoder that generates a certain number of pulses for the amount of movement. If you know the exact time when the timing starts, you can add the elapsed time to get the time when the timing stops. For position control, the current position can be measured by adding the number of pulses to a known starting position. The absolute encoder will continue to send current position information, just like a clock will tell you the current time

DEUPREE (Qingdao) Industrial Technology Co., Ltd. is an integrated enterprise focusing on the research development of automated industrial technology equipment manufacturing. The company’s products mainly include rotary motion sensors, linear displacement sensors, object recognition sensors, laser rangefinders, process control measurement Class instruments, signal detection systems, signal transmission systems, immature drive systems, UPS safety power supply systems, automation equipment energy-saving cleaning auxiliary equipment systems are limited to this, we can also customize flexibly customize according to customer needs to meet different Different needs of customers.