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Absolute Rotary Pulse Encoder GEL 235

Absolute Encoder GEL 235 - Lenord & Bauer Rail Speed Sensors and Rotary Pulse Encoders Absolute Encoder GEL 235

General Absolute Encoder Information

The absolute rotary pulse encoder series GEL 235 delivers for each angular position a unique position value via a digital interface with a resolution up to 28 bit. The absolute encoder series includes Singleturn (ST) with up to 16 bit and Multiturn (MT) with 12 bit resolution via a mechanical gear.


  • Multiturn with mechanical gear
  • High resolution 28 bit
  • High accuracy ± 0,1°
  • SSI up to 2 MHz
  • SSI-P (SSI-progammable) by use of Parameter-Kit
  • CANopen DS 406, PROFIBUS
  • DP
  • Sin/Cos differential signal with1 VPP
  • Axial / radial connector or cable exit
  • Dew-point-proof Protection class up to IP 67

Unique Nonius-evalution

  • Measuring principle: magnetic, high resolution
  • Evaluation: Nonius-principle
  • Measuring scale: metallic code dis

Compact Design for this Absolute Encoder Series

With a standard flange size of 58 mm the housing length for ST and MT with mechanical gear is less than 50 mm.

Robust Construction

  • Resilient anodised aluminium housing, double-bearings
  • The 12 mm steel encoder shaft and the steel code disc form a single robust unit
  • The temperature coefficient of all rotating parts is uniform
  • Withstands high shock and vibration levels and high acceleration rates

Nonius-Algorithm (Vernier-Algorithm)

The measurement principle of the GEL 235 is based on the magnetic scanning of a code disc made of ferro-magnetic steel, the so called nonius-disc. Magneto-Resistive sensors scan three tracks and deliver three corresponding sinusoidal signals. The phase relation of those three sinusoidal signals is unique with one revolution. Based of the Nonius-principle this phase relation is evaluated and delivers with high resolution and accuracy the absolute position.


The absolute encoder supplies the position values in a binary or gray code by use of a fast SSI-interface. In addition high interpolateable Sin/Cos differential signals with 1 Vpp are delivered. The programming of code, resolution, counting direction and Preset values is optionally possible. With 28 bit resolution and a high data rate up to 2 MHz for SSI mode even highly dynamic motion processes are well controlable. A connectable bus-cap enables the profiles CANopen DS 406 and PROFIBUS DP ENCODER PROFIL V1.1. Integrated rotary selectors for the encoder ID and data rate, a switchable on terminal resistor and diagnostic LEDs supports a fast startup.

Magnetic measuring principle

The magneto-resistive scanning of a ferro-magnetic steel- disc offers significant advantages:
  • suitable for all standard application and furthermore for Real-Heavy-Duty use
  • withstands high shock / vibration level
  • not influenced by dirt or oil mist
  • long term stable temperature characteristics
  • full functionality in the presence of condensation:dewpoint-proof
  • no aging of the magnetic sensor elements
  • withstand aggressive media
Absolute Encoder GEL 235 - Lenord & Bauer Rail Speed Sensors and Rotary Pulse Encoders
With additional bus caps all mechanical variants of the GEL 235 can be used for the fieldbus profiles

Technical Data

Incremental deviation < 0.01°
Repeatability < 0.01°
Accurary ± 0.1° (> 11 Bit)
Electrical data
Operating voltage 10 to 30 V DC with reverse voltage protection (option: 5 V - 5%, +25%)
Power consumption < 1.6 W, without load
Resolution Singleturn (ST) 8, 9, 10 to 16 Bit (measuring steps over 360°)
Resolution Multiturn (MT) 4, 8, 12 Bit (revolution, mechanical gear)
Interface SSI, PROFIBUS Encoder Profile V 1.1, CANopen Encoder Profile DS406
Sin/Cos analogue signal Sin/Cos difference signal 1 VPP, 64 periods per resolution
Mechanical data
Housing diameter, housing length
58 mm, 46.5 mm
Clamping flange Distance contact point : 5 mm Shaft load (radial/axial) at 1,000 min-1 = 160 N / 80 N, at 6,000 min-1 = 100 N / 80 N
Synchro flange Distance contact point: 10 mm Shaft load (radial/axial)at 1,000 min-1 = 70 N / 50 N, at 6,000 min-1 = 50 N / 40 N
Semi hollow shaft Distance contact point: 1 mm Shaft load (radial/axial) at 1,000 min-1 = 100 N / 20 N, at 6,000 min-1 = 40 N / 20 N
Material anodised aluminium
Weight Singleturn 300 g
Weight Multiturn 310 g
Operating speed (limit value) Singleturn 12,000 min-1
Operating speed (limit value) Multiturn 10,000 min-1, 12,000 min-1(short time)
Shaft sealing ring (optional)
Protection class: IP 67, Material: Viton, reduced operating speed (max. 6,000 min-1)
Cable (optional) halogen-free PUR (6 x 2 AWG, shielded)
Operating speed
< 3 Ncm
Ambient data
Protection class IP 64, IP 67 (optional)
Shock protection (IEC 68, 2-27) 2000 m/s², 11 ms
Vibration protection (IEC 68, 2-6) 200 m/s², 10 to 2,000 Hz
Working temperature range -40 °C to 100 °C
Operating temperature range -40 °C to 105 °C (120 °C short time)
Storage temperature range -40 °C to 85 °C
Relative humidity of air max. 100 %
Condensation permissible
EMC EN 61000-6-1 to -4
Insulation strength Ri > 1 M? at 500 V AC

Pin layout SSI, Sin/Cos

Absolute Encoder GEL 235 Pin Layout - Lenord & Bauer Rail Speed Sensors and Rotary Pulse Encoders
Absolute Encoder GEL 235 Cable Layout - Lenord & Bauer Rail Speed Sensors and Rotary Pulse Encoders
PRESET adjustment SSI, SSI-P

At any given rotary position the output signals can be set to preset values. As default the singleturn is to set 2n-1and the multiturn is set to half of its maximum value. The preset can be set electrically by applying Vs to the Preset line for t > 100 ms (do not apply permanently). Alternatively, a preset pushbutton is optionally available, recessed in the encoder base (IP 67). This is to be pushed with a blunt pin for t > 100 ms. By using the optional parameter kit, the preset values can be freely defined.

Counting direction

With view on the encoder shaft the position value increases by rotating the shaft clockwise (CW) (default setting). By applying VS permanently to the CW/CCW line the position value will increase when rotating the shaft counter-clockwise. CCW = increasing position values while turning the encoder shaft clockwise CW = increasing position values while


Using SSI protocol the allowed data rates are reduced as the cable length increases. It is recommended that the wires of Clock and Data are each in twisted pair configuration each while the cable is shielded.

Cable length

Using SSI protocol the allowed data rates are reduced as the cable length increases. It is recommended that the wires of Clock and Data are each in twisted pair configuration each while the cable is shielded.

Temperature Range

The storage temperature of -40C up to 85C is restricted by the packaging material. A working temperature range from -40C up to 100C is permissible, in which a mounted encoder is not allowed to exceed this temperature range. Within the allowed working temperature range the functionality of the absolute rotary encoder is assured (DIN 32878), specifically when the temperature is measured at the encoder housing.

The encoder temperature is affected by the installation conditions (thermal conduction, thermal radiation), the selfheating (bearing friction, electrical power dissipation) and the environmental temperature.

Depending on the operating conditions of the encoder, the working temperature of the encoder can be higher than the environmental temperature.

Depending on the power supply from 5 V DC to 30 V DC a self-heating of up to 10C can occur. At high rotation speeds > 5000 min-1a self-heating caused by bearing friction of up to 20C is possible. If the encoder is operated close to its maximum permissible specifications several parameters can affect encoder self-heating. In this case the environmental temperature has to be reduced by suitable methods

Technical data SSI
Output code Binary, gray
Transmission Max. 1,200 m depending on transmission rate
The immunity to interference High immunity to interference via symmetrical transmission
Direction of rotation Adjustable, standard clockwise (CW) with view on the encoder shaft, increasing position values
Preset About input level, software optional with pushbutton
SSI-P (SSI-programmable) Option: software and hardware (parameter kit)

Technical data PROFIBUS DP
Interface PROFIBUS DP, Encoder Profile V 1.1
Supply voltage 10 to 30 V DC
Cable diameter 8 mm
Connection Via bus cap as T-Connector, alternatively cable gland or M12 plug, diagnostics LED, I/O DC-isolated (inductive coupling)
Programmable function Resolution, Preset, offset, counting direction, speed output, acceleration output, output of work areas relative to determined values, scalable step number (decimal/binary), multiplier for measuring of lengths auto-recover-to-bus;
Output code Binary
Data rate 9,6 kBit/s up to 12 Mbit/s adjustable via bus master
Sensor-ID 1 to 125 adjustable via rotary selector
Terminal resistor Switchable via bus cap (both DIP-Switchers at ON)
Operating temperature -40 °C to 85 °C (for short time 100°C)

Lenord & Bauer: Rail Speed Sensors & Rotary Pulse Encoder

Other products relating to GEL 235 are: GEL 15X, GEL 15XF, GEL 15xSSI, GEL 2035, GEL 2310, GEL 235 Accessories