What are encoders? A glance at encoder cables and assemblies

1.1 What are encoders

In industrial control systems, an encoder is a specialized sensor designed to capture position information and transmit this data to other devices within the system. Position information can be determined using three main technologies:

• Optical
• Magnetic
• Capacitive

Regardless of the sensing technology used, the electronic circuitry inside an encoder is responsible for:

• Detecting motion
• Converting mechanical movement into industry-standard electrical signals used for measurement, monitoring, and control purposes.

Learn about servo motors and the characteristics of servo cables

1.2 Applications of encoders

Encoders are used to determine the position, speed, and direction of rotation of a motor shaft or other mechanical movements. They provide essential feedback information required for precise control in a wide range of applications, such as:

• Rotary table positioning
• Pick-and-place systems
• Machine assembly
• Packaging equipment
• Industrial robotics
• And many other automation applications

Regardless of the type, all encoders provide a method for detecting a reference or home position, which is used as a reference point for position control.

Signal quality is a critical factor that determines the reliability of encoder operation. Therefore, selecting the right cable to meet the requirements of each application is essential. Encoder cables are designed to transmit the encoder’s output signals - which may include multiple signal channels to the control device (PLC, servo drive, controller…).

Although encoder cables typically operate unnoticed in the background of the system, they are an indispensable link in the data transmission chain between position sensors and control units. They ensure that information related to position, speed, and operating status is transmitted accurately, continuously, and reliably.

Since encoders often operate in industrial environments with high levels of electrical noise, encoder cables are engineered with specific technical characteristics that distinguish them from standard signal cables.

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3.3 Encoder cables are shielded

Encoder cables are typically equipped with EMI shielding, as they are often installed in parallel with power cables, motors, frequency inverters, servo drives, and other sources of electrical noise. Shielding protects encoder signals from external interference, ensuring that pulses are transmitted and received accurately.

Common shielding solutions include:

• Basic shielding solution: A combination of aluminum foil shielding and a drain wire. This provides a moderate level of noise protection and is suitable for cost-sensitive applications.
• Copper braided shielding: Ensures optimal performance for high-speed and high-frequency applications.
• Combined foil and braided shielding: For applications where EMI is a critical concern, the combination of both foil and braided shields delivers the highest level of noise protection and signal reliability.

Connectors are widely used today, allowing users to easily disconnect and reconnect cables whenever required. During manufacturing, encoders are equipped with specific pin configurations designed to match a defined connector standard. A variety of connector types are used for encoder cables:

4.1 MS connectors

MS connectors feature a circular design with fine threads. This type of connector is suitable for encoder cables operating under harsh working conditions. However, it also has certain drawbacks, such as longer installation time and the risk of thread damage during handling or repeated installation.

4.2 M12 circular connectors

M12 circular connectors are designed with a quick-lock mechanism, making them easier to install compared to MS connectors. With a compact diameter of only 12 mm, they require minimal installation space. M12 connectors are commonly used with absolute encoders.

4.3 M17 connectors

M17 connectors operate on a similar principle to M12 connectors. However, they are waterproof, easy to lock, and lightweight, making them well suited for use in wet or high-humidity environments.

4.4 M23 connectors

M23 connectors are designed for connecting rotary encoders to servo motors and electric motors in industrial systems. They offer robust protection and additionally allow signal transmission and power supply through the same cable assembly.

4.5 Bayonet connectors

Bayonet connectors help prevent incorrect cable-to-pin connections and provide simple and secure locking once the cable is inserted into the correct position. The locking principle is straightforward: the connection is secured by turning the connector clockwise by a quarter turn.

4.6 Sub-D connectors

Sub-D connectors are among the most compact connection solutions available. However, their mounting principle requires direct access to the encoder housing. Due to their relatively low protection level, Sub-D connectors are typically used in integrated systems where installation space is limited and environmental conditions are normal.

Explore our cable connector catalog

HELUKABEL’s TOPGEBER encoder cables are specifically developed for continuous operation and applications requiring precise and uninterrupted position feedback. Designed for excellent noise immunity, high mechanical durability, and outstanding flexibility, TOPGEBER cables ensure reliable encoder signal transmission even in continuously moving systems, industrial robotics, CNC machines, and automated production lines.

5.1 Incremental encoder cables for fixed or not constantly movement applications

TOPGEBER 511 PVC cable has PVC outer sheath and is available in green (DESINA® standard) or orange, complying with the requirements of Siemens, Lenze, and Bosch Rexroth systems. This cable is used as a connecting cable for tachometers, brakes, and pulse generators in industrial equipment, machine tools, as well as control and automation systems.

Incremental Feedback-Cable is widely used in machinery construction, control equipment, and plant engineering due to their ability to transmit data and signals with high accuracy and reliability.

5.2 Encoder cables for moving applications

The following encoder cables are especially suited for continuous operation in drag chains, industrial robotics, and handling equipment, thanks to their ability to transmit data and signals with high accuracy and long-term stability.

• TOPGEBER 512 PUR: compatible with systems from Siemens, Bosch Rexroth, Lenze, Berger Lahr, B+R, Heidenhain, Baumüller.
• Incremental Feedback Cable-C-PUR: is designed to transmit control signals for positioning and operational characteristics. It is also used as a highly flexible connecting cable for tachometers, brakes, and pulse generators in applications subject to high mechanical stress in plant engineering, machine construction, and control and automation systems.
• Tachofeedback cable: are used for motor speed control and actual value measurement during operation.

To ensure encoder signals remain stable, accurate, and reliable in automated systems, HELUKABEL’s pre-assembled encoder cables with connectors are developed as a complete, ready-to-install solution, designed for immediate operation across a wide range of working conditions.

HELUKABEL offers both static and dynamic versions, providing flexible solutions for fixed installations as well as continuously moving applications such as industrial robots, CNC machines, conveyor systems, and automated production lines. The cables are available with a wide variety of connector types, enabling easy integration into existing systems and ensuring compatibility with widely used standards from leading automation manufacturers, including Siemens, Lenze, Rockwell and Allen-Bradley.

6.1 Encoder cable assembly according to Siemens standard