German ERMA encoder ERMA model ERMA price

ERMA encoder is a new type of angle or displacement measurement device. Its principle is to use magnetoresistive elements to measure the angle or displacement of changing magnetic materials. Changes in the angle or displacement of the magnetic material cause changes in resistance or voltage, which are processed by a microcontroller to output pulse signals or analog signals for measurement purposes. Concentric code tracks extend from the center of the magnetic encoder disk outward to the edge. Each layer of code track has twice as many divisions as the inner layer. The first layer has only one transparent sector and one opaque sector; the second layer at the center has two transparent sectors and two opaque sectors; and the third layer of code track has four transparent sectors and four opaque sectors. The built-in sensor head is compact, suitable for small installation spaces, and features a high protection rating design, making it suitable for harsh environments. In industrial applications, it avoids the sensitivity to environmental pollution common in optical encoders, increasing long-term system stability.

ERMA Encoder Classification

According to working principles, encoders can be divided into incremental and absolute types. Incremental encoders convert displacement into periodic electrical signals, which are then converted into counting pulses, with the number of pulses representing the magnitude of displacement. Each position of an absolute encoder corresponds to a specific digital code, so its reading depends only on the start and end positions of the measurement, not on the intermediate process. Rotary incremental encoders output pulses during rotation, and their position is determined by counting equipment. When the encoder is stationary or power is lost, the position is retained by the internal memory of the counting equipment. Thus, after a power loss, the encoder must not move; otherwise, interference causing pulse loss during operation after power restoration will shift the zero point remembered by the counting equipment. This shift amount is unknown until erroneous production results occur. The solution is to add a reference point. Each time the encoder passes the reference point, the reference position corrects the memory position of the counting equipment. Before reaching the reference point, position accuracy cannot be guaranteed. Therefore, in industrial control, methods such as finding the reference point before each operation or homing at startup are used. For example, the positioning of printers and scanners uses the principle of incremental encoders. Each time they are powered on, we hear a series of clicking sounds as they search for the reference zero point before starting work.

ERMA Encoder Features

When the encoder shaft rotates, corresponding pulses are output. The determination of rotation direction and the increase or decrease in pulse count are achieved through the rear direction-detection circuit and counter. The counting start point can be set arbitrarily, allowing for multi-turn infinite accumulation and measurement. Additionally, the Z signal, which outputs one pulse per revolution, can serve as the reference mechanical zero position. The encoder shaft outputs a fixed number of pulses per revolution, determined by the number of lines on the encoder grating. To improve resolution, the original pulse count can be multiplied using the A and B signals with a 90 degree phase difference, or a high-resolution encoder can be used.

ERMA Encoder Component Differences

From single-turn absolute encoders to multi-turn absolute encoders. An absolute rotary single-turn absolute encoder measures the engraved lines on each track of the optical code disk during rotation to obtain a unique code. When the rotation exceeds 360 degrees, the code returns to the origin, which violates the principle of uniqueness for absolute encoding. Such encoding can only be used for measurements within a rotation range of 360 degrees and is referred to as a single-turn absolute encoder. For measuring rotations exceeding a range of 360 degrees, a multi-turn absolute encoder is used. The encoder manufacturing employs the mechanical principle of clockwork gears. As the central code disk rotates, another set of code disks (or multiple sets of gears and code disks) is driven through gear transmission. This adds revolution counting to the single-turn encoding, thereby expanding the measurement range of the encoder. Such an absolute encoder is called a multi-turn absolute encoder. It also determines the code by mechanical position, ensuring that each position code is unique and non-repeating without the need for memory. Another advantage of multi-turn encoders is that, due to the large measurement range, there is often considerable margin in use. Thus, it is not necessary to struggle to find the zero point during installation; a certain intermediate position can be used as the starting point, greatly simplifying the difficulty of installation and commissioning.

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