編碼器電纜：如何指定正確的信號電纜
編碼器電纜將編碼器輸出信號（可能包括多個通道）傳輸?shù)娇刂圃O(shè)備。編碼器電纜信號傳輸可能會因許多因素而弱化，包括傳輸時間長、電纜電容高和極端 EMI。如果指定得當，用戶的編碼器電纜可以補償所有這三個問題。
An encoder cable transmits encoder output, which may include multiple channels, to a control device. Encoder cable signal transmission can be degraded by many factors including, long transmission runs, high cable capacitance and extreme EMI. Properly specified, your encoder cabling can compensate for all three of these issues.
編碼器電纜的選擇取決于應(yīng)用條件，但有一些經(jīng)驗準則：
雙絞線布線可最大限度地減少電纜中的電感和電容。長距離安裝時這種類型的編碼器接線尤為重要。
使用至少規(guī)格24的電線。
屏蔽對于抗噪性至關(guān)重要。整體屏蔽的電纜是最低限度的，但在高噪聲環(huán)境中，應(yīng)考慮單獨屏蔽的電線。
為了最大限度地減少長距離電壓降，請選擇低電阻和低電容的電纜
對于噪聲非常高的環(huán)境，帶有差分接線的差分編碼器提供了一種有效的噪聲過濾方式。
對于非常長的距離，請考慮使用中繼器加強信號或編碼器分離器.
選擇一種連接器，它既能提供您所需的環(huán)境保護，又能兼顧易用性、成本、尺寸和可用性。
The choice of encoder cable depends upon the conditions of the application but there are a few rules of thumb:
Twisted-pair wiring minimizes inductance and capacitance in the cable. Installing this type of encoder wiring is particularly important over long distances.
Use a minimum of 24-gauge wire.
Shielding is essential for noise immunity. A cable that is shielded overall is the bare minimum but in a high-noise environment, individually-shielded wires should be considered.
To minimize voltage drop over long reaches, choose cable with low resistance and low capacitance
For very high-noise environments, differential encoders with differential wiring provide an effective way to filter out noise.
For very long distances, consider strengthening the signal with a repeater or encoder splitter.
Choose a connector that provides the environmental protection you require along with a balance of ease-of-use, cost, size, and availability.
編碼器布線方案
Encoder Cabling Schemes
編碼器的類型將決定傳感器與讀出設(shè)備（控制器、驅(qū)動器、計數(shù)器/顯示器等）通信所需的電線數(shù)量。增量編碼器將需要一根電源線，一根接地線，每個附加通道一根線。增量編碼器有多種類型，包括：
用于跟蹤速度和位移的單通道編碼器設(shè)計（A 通道）
正交編碼器設(shè)計（A 和 B 通道），也跟蹤方向
正交編碼器設(shè)計帶有一個額外的索引通道（Z 通道），每轉(zhuǎn)建立一次初始位置
帶有附加換向軌道（U、V 和 W 通道）的編碼器
對于高噪聲環(huán)境，差分編碼器可能是合適的解決方案。在這些設(shè)計中，差分線路驅(qū)動器為每個通道生成兩個輸出：正常信號及其補碼。每個信號中都會出現(xiàn)任何噪聲尖峰，使接收器能夠?qū)⑵渥鳛楣材Ｔ肼暈V除。實施此方案需要為每個通道使用兩條線。
The type of encoder will determine the number of wires necessary to enable the sensor to communicate with the readout device (controller, drive, counters/display, etc.). Incremental encoders will require one wire for power, one wire for ground, and one wire for each additional channel. Incremental encoders are available in a variety of types including:
Single-channel encoder designs (A channel) to track speed and displacement
Quadrature encoder designs (A and B channels), which also track direction
Quadrature encoder designs with an additional index channel (Z channel) to establish a home position once per revolution
Encoders with additional commutation tracks (U, V, and W channels)
For high-noise environments, a differential encoder may be an appropriate solution. In these designs, a differential line driver generates two outputs for each channel: the normal signal and its complement. Any noise spikes will appear in each signal, enabling the receiver to filter it out as common-mode noise. Implementing this scheme requires two wires for each channel.
表 1：增量編碼器接線方案（Table 1: Incremental encoder wiring schemes）
絕對編碼器將絕對位置作為多位數(shù)字發(fā)送。它們可以使用并行接線、現(xiàn)場總線或點對點接線進行連接。每種類型所需的導(dǎo)體數(shù)量各不相同。
Absolute encoders transmit absolute position as a multi-bit digital word. They can be connected using parallel wiring, fieldbus, or point-to-point wiring. The number of conductors needed for each type varies.
表 2：絕對編碼器接線方案（Table 2: Absolute encoder wiring schemes）
編碼器電纜質(zhì)量的重要性
Importance of Encoder Cable Quality
成功的編碼器的驅(qū)動通信取決于編碼器向接收器發(fā)送凈電壓脈沖流的能力。
特別是如果讀出設(shè)備使用更復(fù)雜的技術(shù)，例如正交編碼器上的邊緣檢測，則信號由具有良好信噪比的方脈沖組成是很重要的。脈沖的電壓電平也很重要。一些驅(qū)動器和控制器具有電壓檢測閾值，并且不會檢測低于特定電壓的脈沖。
Successful encoder to drive communication depends on the ability of the encoder to send a stream of clean voltage pulses to the receiver.
Particularly if the readout device is using more sophisticated techniques such as edge detection on a quadrature encoder, it is important that the signal consists of square pulses with a good signal-to-noise ratio. The voltage level of the pulses is also important. Some drives and controllers have thresholds for voltage detection, and will not detect pulses below a certain voltage.
為長期運行指定編碼器電纜
Specifying Encoder Cables for Long Runs
有幾個因素會降低信號質(zhì)量，其中最重要的兩個是傳輸距離和噪聲環(huán)境。電纜會受到電容、電感和電阻的影響，所有這些都會導(dǎo)致電壓降。高電容會增加電纜的 RMS 電流消耗。傳輸時間越長，效果就越大。
為了最大限度地提高信號強度，首先應(yīng)將接收設(shè)備放置在盡可能靠近編碼器的位置。除此之外，您還可以對編碼器布線做一些事情來提高性能。首先指定您能負擔(dān)得起的最優(yōu)質(zhì)的低電容電纜。每條電纜都有電容，但電容越低，您在傳輸過程中丟失的信號就越少。增加的電容會提高導(dǎo)線的 RMS 電流消耗，電流消耗越高，信號越低。此外，產(chǎn)生更多安培數(shù)會觸發(fā)編碼器輸出驅(qū)動器發(fā)熱。太多會使編碼器進入熱關(guān)斷狀態(tài)。
Several factors degrade signal quality, the two most important being transmission distance and noise environment. Electrical cables suffer from capacitance, inductance, and resistance, all of which act to cause a voltage drop. High capacitance increases the RMS current draw of the cable. The longer the travel, the greater the effect.
To maximize signal strength, the first response should be to locate your receiving device as close as possible to the encoder. Beyond that, there are several things you can do with encoder cabling to improve performance. Start by specifying the best quality low-capacitance cable you can afford. Every cable has capacitance but the lower it is, the less of the signal you will lose in transit. Increased capacitance raises the RMS current draw of the wire and the higher the current draw, the lower the signal. In addition, generating more amperage triggers heating in the output driver of the encoder. Too much can throw the encoder into thermal shutdown.
為高噪聲環(huán)境指定編碼器電纜
Specifying Encoder Cables for High Noise Environments
正確的布線可以減少或抑制噪聲，即使在非常嘈雜的環(huán)境中也能提供強大的編碼器信號。建議為所有應(yīng)用提供某種形式的編碼器電纜屏蔽層。為獲得最佳性能，應(yīng)保護每根電線。最常見的屏蔽類型是帶有加蔽線的箔護套。在電纜周圍使用，這以經(jīng)濟的價格提供了足夠的性能。編織屏蔽提供更好的性能。
另一個關(guān)鍵的噪聲抑制方法是選擇雙絞線。這種類型的編碼器電纜消除了電感并有助于防止串擾。對于差分編碼器信號，可以使用雙絞線來傳輸編碼器信號及其補碼。對于高頻、高速應(yīng)用，雙絞線單獨包裹并收集到由編織線屏蔽層保護的電纜中，即使在高噪聲環(huán)境中也能提供良好的性能。
The right cabling can reduce or suppress noise, delivering strong encoder signals even in a very noisy environment. Dynapar recommends some form encoder cable shield for all applications. For best performance, each individual wire should be protected. The most common type of shielding is a foil jacket with a drain wire. Used around the cable, this provides adequate performance at an economical price. Braided shielding delivers better performance.
Another key noise-suppression method is to choose twisted-pair wiring. This type of encoder cable cancels inductance and helps prevent cross-talk. For differential encoder signals, a twisted pair of cables can be used to carry the encoder signal and its complement. For a high-frequency, high-speed application, twisted-pair wires individually foil wrapped and collected into a cable protected by a braided-wire shield will provide superior performance even in a high-noise environment.
指定正確的連接器
Specifying the Right Connector
如果沒有正確指定，連接器可能成為電纜中最薄弱的環(huán)節(jié)。除非直接端接尾纖，選擇合適的編碼器電纜后，在選擇連接器時仍然需要考慮幾個因素，包括環(huán)保、易用性、尺寸和成本。對于采購靈活性和未來的現(xiàn)場更換，連接器的通用性也應(yīng)該是一個考慮因素。
與許多工業(yè)應(yīng)用一樣，環(huán)境因素優(yōu)先。在高污染或潮濕的條件下，M12 或鎖定連接器通常會提供良好的保護并且相當普遍。接下來，考慮機械和安裝要求。閂鎖連接器體積龐大，但只需一把螺絲刀即可在現(xiàn)場輕松安裝。M12 連接器結(jié)構(gòu)緊湊，但需要焊接。
The connector can become the weakest link in the cable if not correctly specified. Unless directly terminating a pigtail, after selecting the right encoder cable, there are still several factors to consider when choosing a connector including environmental protection, ease-of-use, size, and cost. For sourcing flexibility and future field replacements, connector commonality should also be a consideration.
As with many industrial applications, environmental considerations take precedence. In conditions with high contamination or moisture, an M12 or latching connector will typically provide good protection and are fairly common. Next, consider mechanical and installation requirements. Latching connectors are bulky but are easy to install in the field with just a screwdriver. M12 connectors are compact but require soldering.
表 3：常見編碼器電纜連接器比較（Table 3: A comparison of common encoder cable connectors）
本文英文原文轉(zhuǎn)載自：DYNAPAR-Encoder Cables: How to Specify the Right Signal Cable
本文翻譯by愛澤工業(yè)，如有偏頗，敬請指正。
