Beginner’s Guide to Programmable Encoders

Encoders are electromechanical devices that convert rotational movement into equivalent electronic signals. These electronic signals can simply provide a ticking interval (incremental) or indicate a specific position during rotation (absolute).

Encoders are an integral component of automation, usually used as feedback for a motion control system. There are different types of encoders depending on the area of application, available resources, and other process-related requirements. Programmable encoders are a unique variety that allows the user to program specific parameters.

 

What are Programmable Encoders?

As the name suggests, programmable encoders allow personnel to program encoder parameters according to the process or application requirements. In contrast to conventional encoders, where the output is purely an electrical signal and there are no parameters, forcing the user to select from the pool of available encoders, these programmable encoders allow for the integration of a single product for varying process requirements.

 

Programmable encoders allow adjustment of basic parameters such as pulse train and reference/index signal. Image used courtesy of maxon

 

Some of the parameters that can be programmed include

• Pulse number: The number of pulses in a complete revolution, which also indicates the resolution of an encoder
• Output type: TTL or HTL (transistor-transistor, or high transistor logic styles). These are the common output types, indicating the voltage levels of high and low signals.
• Pulse sequence or direction – Counter ClockWise (CCW) and ClockWise (CW): The sequence of pulses by encoders are typically determined by two trains of pulses 90° apart from each other. 
• Reference Signal: A signal indicating the passage of a specific number of pulses or positions. Typical values include 90° or 180°

 

How are Encoders Programmed?

Commonly, there are two methods of programming programmable encoders: standalone programming devices and PC-based software.

Programming Device

The programming device comprises a battery-operated, handheld device connected to the encoder through a communication interface. The programming device can also be used to store the programming parameters of encoders, easing the effort of commissioning multiple encoders in similar equipment.

 

A handheld programming device directly connects to the encoder through a communication cable for configuration. Image used courtesy of Baumer

 

PC-Based Software

For PC-based options, software installed on the PC is used to program encoders. An adapter cable with an intermediate device facilitates communication with the encoder. All three components, the PC, programmable encoder, and intermediate device, are usually connected through a common serial, USB, or IO-Link port, depending upon the device model.  

For some models, using wireless-based remote devices to program the encoders is also possible. In this case, the intermediate device acts as an internet gateway for the encoder and PC, and uses Wi-Fi for connectivity. This feature allows for programming the encoder through any device capable of connecting to the internet. The software is accessed via the internet without the need to install it on any device, although naturally, security becomes a concern in such cases. 

 

Advantages of Programmable Encoders

There are some advantages of programmable encoders over conventional encoders which should be examined before making a final design choice.

Diversified Replacement

The ability of a programmable encoder to adjust and program its parameters allows for an easier replacement without worrying about the original encoder part number once it provides the programming functionality.

This is in contrast to conventional encoders, where the part number having the same specification has to be procured whenever replacement is required. This often becomes critical for aging facilities, where old equipment is common, and engineers face the problem of parts obsolescence. For some legacy equipment, this situation becomes more intense as the original manufacturer has often shut down its operation, and after-sales support is unavailable.

Suppose equipment is supplied with a programmable encoder. In that case, it can be easily replaced by another version of the programmable encoder, even if the encoder manufacturer has stopped manufacturing that specific part.

Smaller Number of Spares Required

As a closely related advantage, one or fewer quantities can be stocked as spare parts for programmable encoders for further utilization. A single programmable encoder can be configured for various programmable encoders for various applications and equipment.

For conventional encoders, it is necessary to stock encoders for every different part number. Because an encoder of one specification cannot be replaced with an encoder having a different specification, it increases the stock requirement for the conventional encoder.

Online/Remote Diagnostic Tools

PC-based software for programming allows engineers to monitor the actual condition and signal state of the encoder. When connected, it displays the actual output of the encoder, such as the position or angle. This feature can be used during maintenance or troubleshooting to diagnose motion control systems without stopping the machine.

Online diagnostics also allow for testing of the installed encoders without disconnecting the wiring and dismantling the machine. It is especially helpful when the encoders are installed in hard-to-reach areas, which is normally the case in most machines.

Storage of Configuration Data

As mentioned previously, storing configuration data electronically for later use, such as copying and uploading to another programmable encoder, is possible. This helps engineers store and recall process parameters for future reference, such as replacing and upgrading.

 

It is possible to store configuration data in a programmable encoder electronically for later use. Image used courtesy of Encoder Products

 

For conventional encoders, it often becomes difficult to remember the specifications. Documentation is often less than perfect, and labels can fade or tear away. Creating hard copies of the encoder specification may also prove difficult because manual records can be lost or misplaced.

Increased Flexibility for Machine Builders

For machine builders and manufacturers, the end user is often uncertain about their requirements during the initial stages of the project. For example, a food and beverage manufacturer may not be sure about the capacity of the juice filling machine until it gets a forecast from its marketing department, or more simply, the machine buyer has changed their mind for whatever reason.

In this prior case, programmable encoders could give engineers of machine builders to easily incorporate the changes by amending the configuration of encoders without changing the encoder and mechanical structure.

For conventional encoders, it is impossible to incorporate any change once the machine builder has started using the encoder's input in programming. The only way to incorporate the changes is to alter the encoder itself through major hardware adjustments or to hope the original configuration is flexible enough for adaptation to the new design.

 

Flexible and Adaptable Motion Control

Using programmable or traditional encoders for your motion control applications depends upon various factors in your organization. However, if your priorities include advancing automation, innovation, diagnostics, efficient workforce utilization, and online connectivity, the programmable encoder might just be the simple best answer!

 

Featured image (modified) used courtesy of Baumer