A range of innovative rotary encoders opened to fieldbus
The opto-electronic rotary encoder is an angular position sensor.
Mechanically coupled to a driving spindle of a machine, the shaft of the encoder rotates a disc that comprises a succession of opaque and transparent sectors.
Light from light emitting diodes (LEDs) passes through the transparent sectors of the disc as they appear and is detected by photosensitive diodes.
The photosensitive diodes, in turn, generate an electrical signal which is amplified and converted into a digital signal before being transmitted to a processing system or an electronic variable speed drive.
The electrical output of the encoder therefore represents, in digital form, the angular position of the input shaft.
Types of rotary encoders:
Incremental encoders:
Calculation of position and/or speed by counting pulses per revolution,
Parameterable version (resolution 256 to 80 000 points).
Absolute single turn encoders:
Reading position within a revolution
Absolute multiturn encoders:
Reading position within a revolution and indication of the number of revolutions
Communicating absolute multiturn encoders:
Reading position and speed with CANopen or PROFIBUS-DP communication interface
Applications
Rotary encoders are used in many industries including packaging, cutting machines, robots, cranes, material handling, automatic dispensers, printing shops, continuous processes, conveyor systems, etc.
Main characteristics:
Reliability provided by in-line (3 heads) differential optical reading, high tolerance to: the accumulation of dirt, temperature and ageing.
Incremental and absolute encoders:
3 housing diameters: 40, 58 and 90 mm
2 shaft types: modular solid or through shafts using reduction collars
All resolutions: from 100 to 80 000 points
Communicating absolute multiturn encoders:
Housing diameter: 58 mm
2 shaft types: modular solid or hollow shafts using reduction collars
Resolution: 8192 points /4096 turns
Integration in the SyCon software environment.
7 characteristics to be established:
Function
Incremental encoder Provides counting indication.
Single turn absolute encoder Provides absolute position within each revolution.
Multiturn absolute encoder Provides absolute position within each revolution and indicates total number of revolutions.
Diameter of housing
Incremental encoders Ø 40, 58 and 90
Single turn and multiturn absolute encoders Ø 58 and 90
Diameter of shaft
Ø 6 mm to 30 mm, depending on model
Reduction collars For Ø 58 and 90 mm encoders, with Ø 14, 15 and 30 mm through shaft, reduction collars are available to reduce the diameters: - from 14 to 6, 8, 10 and 12 - from 15 to 6, 8, 10, 12 and 14 - from 30 to 12, 16, 20 and 25.
Type of shaft
Solid shaft
The shaft of the encoder is mechanically linked to a drive shaft using a flexible coupling, which eliminates alignment inaccuracies.
Through shaft/Hollow shaft
The encoder is mounted directly on the drive shaft. A flexible mounting kit prevents encoder rotation and compensates for alignment inaccuracies.
Connection method
Pre-cabled with 2 m long shielded cable or M23/M12 connector.
Radial type connection.
Resolution
Number of points per revolution.
Number of revolutions (for multiturn absolute encoders).
On Ø 58 parameterable incremental encoders, this resolution can be adjusted using dip switches (multiplication factor up to 16 times on 9 basic resolutions).
Type of output
Incremental encoders 5 V output driver, RS 422, 4.75…30 V. Push-pull output driver, 5…30 V, 11...30 V.
Single turn absolute encoders (depending on model) Push-pull output driver, 11…30 V, binary code or Gray code. SSI output without parity, 13-bit clock, 11…30 V, binary code or Gray code.
Multiturn absolute encoders (depending on model) SSI output without parity, 25-bit clock, 11…30 V, binary code or Gray code.
Parallel outputs obtainable using converter connecting cables The SSI versions can be converted to a parallel version by using the deserialisation connecting cable.
