编码器电缆：如何指定正确的信号电缆

编码器电缆将编码器输出信号（可能包括多个通道）传输到控制设备。编码器电缆信号传输可能会因许多因素而弱化，包括传输时间长、电缆电容高和极端 EMI。如果指定得当，用户的编码器电缆可以补偿所有这三个问题。

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.

编码器电缆的选择取决于应用条件，但有一些经验准则：

双绞线布线可最大限度地减少电缆中的电感和电容。长距离安装时这种类型的编码器接线尤为重要。

使用至少规格24的电线。

屏蔽对于抗噪性至关重要。整体屏蔽的电缆是最低限度的，但在高噪声环境中，应考虑单独屏蔽的电线。

为了最大限度地减少长距离电压降，请选择低电阻和低电容的电缆

对于噪声非常高的环境，带有差分接线的差分编码器提供了一种有效的噪声过滤方式。

对于非常长的距离，请考虑使用中继器加强信号或编码器分离器.

选择一种连接器，它既能提供您所需的环境保护，又能兼顾易用性、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.

编码器布线方案

Encoder Cabling Schemes

编码器的类型将决定传感器与读出设备（控制器、驱动器、计数器/显示器等）通信所需的电线数量。增量编码器将需要一根电源线，一根接地线，每个附加通道一根线。增量编码器有多种类型，包括：

用于跟踪速度和位移的单通道编码器设计（A 通道）

正交编码器设计（A 和 B 通道），也跟踪方向

正交编码器设计带有一个额外的索引通道（Z 通道），每转建立一次初始位置

带有附加换向轨道（U、V 和 W 通道）的编码器

对于高噪声环境，差分编码器可能是合适的解决方案。在这些设计中，差分线路驱动器为每个通道生成两个输出：正常信号及其补码。每个信号中都会出现任何噪声尖峰，使接收器能够将其作为共模噪声滤除。实施此方案需要为每个通道使用两条线。

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：增量编码器接线方案（Table 1: Incremental encoder wiring schemes）

绝对编码器将绝对位置作为多位数字发送。它们可以使用并行接线、现场总线或点对点接线进行连接。每种类型所需的导体数量各不相同。

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：绝对编码器接线方案（Table 2: Absolute encoder wiring schemes）

编码器电缆质量的重要性

Importance of Encoder Cable Quality

成功的编码器的驱动通信取决于编码器向接收器发送净电压脉冲流的能力。

特别是如果读出设备使用更复杂的技术，例如正交编码器上的边缘检测，则信号由具有良好信噪比的方脉冲组成是很重要的。脉冲的电压电平也很重要。一些驱动器和控制器具有电压检测阈值，并且不会检测低于特定电压的脉冲。

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.

为长期运行指定编码器电缆

Specifying Encoder Cables for Long Runs

有几个因素会降低信号质量，其中最重要的两个是传输距离和噪声环境。电缆会受到电容、电感和电阻的影响，所有这些都会导致电压降。高电容会增加电缆的 RMS 电流消耗。传输时间越长，效果就越大。

为了最大限度地提高信号强度，首先应将接收设备放置在尽可能靠近编码器的位置。除此之外，您还可以对编码器布线做一些事情来提高性能。首先指定您能负担得起的最优质的低电容电缆。每条电缆都有电容，但电容越低，您在传输过程中丢失的信号就越少。增加的电容会提高导线的 RMS 电流消耗，电流消耗越高，信号越低。此外，产生更多安培数会触发编码器输出驱动器发热。太多会使编码器进入热关断状态。

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.

为高噪声环境指定编码器电缆

Specifying Encoder Cables for High Noise Environments

正确的布线可以减少或抑制噪声，即使在非常嘈杂的环境中也能提供强大的编码器信号。建议为所有应用提供某种形式的编码器电缆屏蔽层。为获得最佳性能，应保护每根电线。最常见的屏蔽类型是带有加蔽线的箔护套。在电缆周围使用，这以经济的价格提供了足够的性能。编织屏蔽提供更好的性能。

另一个关键的噪声抑制方法是选择双绞线。这种类型的编码器电缆消除了电感并有助于防止串扰。对于差分编码器信号，可以使用双绞线来传输编码器信号及其补码。对于高频、高速应用，双绞线单独包裹并收集到由编织线屏蔽层保护的电缆中，即使在高噪声环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.

指定正确的连接器

Specifying the Right Connector

如果没有正确指定，连接器可能成为电缆中最薄弱的环节。除非直接端接尾纤，选择合适的编码器电缆后，在选择连接器时仍然需要考虑几个因素，包括环保、易用性、尺寸和成本。对于采购灵活性和未来的现场更换，连接器的通用性也应该是一个考虑因素。

与许多工业应用一样，环境因素优先。在高污染或潮湿的条件下，M12 或锁定连接器通常会提供良好的保护并且相当普遍。接下来，考虑机械和安装要求。闩锁连接器体积庞大，但只需一把螺丝刀即可在现场轻松安装。M12 连接器结构紧凑，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：常见编码器电缆连接器比较（Table 3: A comparison of common encoder cable connectors）

本文英文原文转载自：DYNAPAR-Encoder Cables: How to Specify the Right Signal Cable
本文翻译by爱泽工业，如有偏颇，敬请指正。