Absolute encoders and incremental encoders
An encoder is an electronic communication device that controls the motion of an operating device/controller. Encoders help determine the speed, number of revolutions, direction or position of a motor or other moving equipment.
Motion converted to electrical signal
Motion is converted by the encoder into an electrical signal. This signal is then read by a control device in a motion control system such as a counter or PLC. An encoder generates pulses and is therefore also called a pulse generator.
The encoder sends a feedback signal that can be used to determine position, speed, count or direction. A motion control system can use this information to send a particular command.
Programmable encoder features
In addition, some encoders have programmable functions such as resolution and direction of rotation. For higher resolution - instead of a square wave - a sine and cosine signal are also used. These encoders are also called sincosencoders. Nowadays, more and more encoders are used with a serial output.
Absolute rotary encoders provide unique position values from the moment they are turned on. This is achieved by scanning the position of a coded element. All positions in these systems correspond to a unique code. Even movements that occur while the system has no power are converted into accurate position values as soon as the encoder is turned back on.
Multiturn encoders are absolute encoders that also count the number of revolutions. A singleturn absolute encoder measures absolute position within one revolution.
Incremental encoders provide information about the angle, position and number of revolutions. The resolution of the incremental encoder is defined by the number of pulses or dashes per revolution that the encoder transmits to the controller for each revolution.
Determining the actual position
The actual position can be determined by the controller by counting the aforementioned pulses or stripes. Each time the encoder is turned on, the count starts from zero, regardless of where the axis is located. The initial homing to a reference point is therefore unavoidable in all positioning tasks, both at control system startup and when power to the incremental encoder is interrupted.
Linear and rotary encoders
There are two different types of encoders. Linear encoders and rotary encoders. Linear encoders respond to motion along a path, while rotary encoders respond to rotational motion. A linear encoder is a sensor, transducer or readhead coupled to a scale that encodes position.
Analog or digital signals.
The sensor reads the scale to convert the encoded position into an analog or digital signal. The analog or digital signal can then be decoded to a position by a digital readout or motion controller.
Encoder for accurate positioning
A rotary encoder - also called an axis encoder - is an electromechanical device that converts angular position or motion of an axis into analog or digital code. Rotary encoders are widely used in applications where accurate position is important, such as industrial controls and robotics. Encoders can send both incremental and absolute signals. Based on the type of signals, encoders are divided into incremental and absolute encoders.
Absolute and incremental encoders
Application areas encoders
- Offshore and maritime: ATEX encoders, Heavy Duty encoders, for use in winches and cable drums.
- Packaging industry: Setting length, width and height of packaging machines.
- Windmills and turbines: Position measurement of blades and monitoring of rotation speed.
- Elevators and hoists: Speed and speed monitoring. Elevator car positioning.
- Windmills and turbines: Position measurement of blades and rotational speed monitoring.
- Metal and woodworking industries: Adjustment of stop and hogote.
- Medical: Positioning of clients and instruments in X-ray, CT or MRI environments.
Smallest absolute multiturn SSI encoder
Industrial designs require innovative products. For specific applications, encoders with reduced dimensions are desired. SCANCON's mini absolute multiturn SSI encoder - SCA36AN - is the smallest absolute encoder available.
Multiturn encoders are absolute encoders that track the number of revolutions in addition to position. Read more about the absolute mini multiturn SSI encoder.
Absolute single-turn encoders - 25 bit resolution
To determine the correct position is some machines and devices require the highest accuracy. Lika Electronic's HS58 absolute encoder has a high resolution of up to 25 bit - 33,554,432 cpr (counts per revolution). The resolution of the absolute encoder is read by an encoded disk and extrapolated to a 25 bit code. Read more about the HS58 absolute encoder.
HS58 absolute encoder features:
- 58-mm flange diameter housing with both solid and hollow shaft
- Temperatures: -25°C to +85°C
- SSI or BiSS C-mode interface
- Additional incremental track (2,048 1Vpp Sine-Cosine signals per revolution)
- Connection: M12/M23 connector or cable
Absolute encoder positioning motor
For fast and precise automatic changeovers, Lika Electronic has developed the RD6 positioning motor. The RD6 positioning motor ensures the correct spindle position through its built-in absolute encoder and drive unit.
The adjustment motor is mounted on positioning spindles for automatic adjustment. Read more about absolute encoder positioning motor.
Incremental drawstring encoder
Lika's incremental drawstring encoder is freely programmable. Due to the free programmability of the incremental encoder, any customer-specific resolution requirement can be met.
Correct information for every application
The incremental programmable encoder delivers the correct and accurate information required, regardless of the industry or application. Read more about programmable incremental pull-cord encoder.
Magnetic absolute encoder without roller bearings - IP69K
Lika's magnetic absolute SMAB encoder has a flat magnetic ring with a large 80mm diameter hollow shaft. The magnetic absolute encoder is suitable for extreme conditions with a high sealing rating of IP69K.
Magnetic encoder features:
- Lateral magnetic readout: 16-18 bit
- High sealing rating: IP69K
- Flat magnetic shaft: 80mm diameter
- Zero, direction of rotation and error indication
- Non-contact detection and maintenance-free
Lika SMLAX rotary encoder - Dual output: absolute and incremental
Lika Electronic's SMLAX rotary encoder features both absolute and incremental sensing and processing electronics in one package. Thus, the SMLAX rotary encoder can read the absolute and incremental tracks encoded on the ring's magnetic tape.
Absolute and incremental measurement system
For example, the absolute position information can be used to detect the position of the stator/rotor at motor start-up, while the incremental information enables speed control. The absolute measurement system achieves 14-bit resolution (16,384 cpr) over the full circumference and provides the absolute position and error bit via the SSI and BiSS interfaces. Read more about the SMLAX rotary encoder.
Robust, high-precision encoder
The absolute encoder ASC85 is Lika's flagship product with hollow through-axis and very high resolution and accuracy. The absolute encoder is ideal for applications such as robotics, radar and antennas, military applications and advanced general industrial applications for high-precision position control.
CB50 rotary encoder - Lika Electronics
Programmable encoder with very high resolution
Scancon's eCODE series encoders use a high-precision interpolating optical system that provides high-resolution measurement. The SCA94DD eCODE encoder is specifically designed for wind power applications working with slow rotating Direct Drive generators. Values are available through the Profibus fieldbus interface. Read more about fieldbus encoders.
The eCODE series encoder comes standard with a number of programmable functions, including resolution and direction of rotation. In addition, it includes diagnostic functions for error and status messages. The encoder can be user-programmable.
Incremental dual output encoder for ATEX Zone 1 with Profibus
Scancon's EXAG Profibus/incremental dual output encoder is designed for use in ATEX Zone 1 with feedback capability to various devices. The dual output encoder has resolution up to 30 bits multi-turn and incremental resolution up to 8192 pulses per revolution.
The standard dual output encoder features a removable cover for on-site modification and by rotary switches and setting the PROFIBUS address.
Safety encoder for speed control
The ReeR Safety Safecoder safety encoder, in combination with the ReeR Mosaic series, is a SIL 3 certified safety monitor for speed control. The encoder is available in shaft or hollow shaft version and supply voltages of 24VDC and 5VDC and has a resolution of 2048 pulses.
The shaft variant has shaft diameter of 12 mm, the hollow shaft encoder has a shaft diameter of 10 mm. The safety encoder has standard IP65 protection rating and optional IP67.
ATEX encoders for hazardous areas
Encoders are potential ignition sources. In hazardous areas, the risk of igniting an explosive mixture must be prevented. Before an encoder can be used in a hazardous area, it must first be certified in accordance with ATEX.
Fortop has several ATEX encoders in its product range. The following incremental encoders are ATEX certified: Scancon REXM, SCA24EX, 2REX, 2QEX, 2CEX and the 2MC-EX-H.
Encoders for offshore and underwater operations
Scancon's SCH68SUB model is an encoder designed specifically for underwater operations. The SCH68SUB is designed and tested for offshore applications that need to operate at water depths of up to 6000 metres (~20,000 feet).
A unique feature of the SCH68SUB is that the encoder can operate at water depths of up to 6,000 metres without any special enclosure. The SCH68SUB is a magnetic incremental encoder with a ø 20 mm or ø 1 inch hollow shaft, a resolution of 2048 ppr and a protection rating of IP68/IP69K. The SCH68SUB is ideal for use in subsea robotics, ROVs (remotely operated vehicle) and other seabed applications requiring motion control or position feedback.
Food and beverage encoders
Scancon's SCH50IB encoder is specially designed for the food industry and other harsh environments. The encoders are manufactured with SAE 51200 industrial chrome steel ball bearings, stainless steel housing and cap and IP67/IP69K protection class.
The food and beverage encoders provide the solution for food processing applications. Solid shaft and hollow shaft models can be used in applications where the encoder is exposed to high pressure and corrosive liquids.