Economical SSI Output Multi-turn Absolute Encoder EX38 Series

  • Universal SSI output, single-turn absolute encoder, Can directly match Siemens, German Beckhoff PLC
  • Wiegand battery multi-turn absolute encoder
  • Multiple resolutions are available, such as 13-bit, 25bit
  • 38mm outer diameter, Clamping flange, servo flange or blind hollow shaft, the international standard structure
  • A “magnetic detection mode”, with excellent impact and vibration resistance
  • Wide operating voltage, low current consumption
  • Housing IP67, shaft IP65
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Operating voltage

10 … 30Vdc polarity protection (recommended 24Vdc power supply)

Current consumption

<35mA (24Vdc) no-load

Output signal

SSI synchronous serial signal, Gray coder(default), Binary coder optional

Signal transmission

Two pairs of RS422, 100 meters (125KHz and recommend special cables, more distance please consult factory)

Linear Resolution


Max laps

4096(Wiegand battery)


Repeatability ± 2BIT (actual accuracy relate to precision of installation and the shaft concentricity )

Clock frequency

The fastest clock frequency can be set 500KHz, recommend 125KHz.

Working temperature

-40 ~ 80 ℃

Storage temperature

-40 ~ 80 ℃

Protection class

Shell IP67, IP65 shaft

Vibration and shock

10g, 10 ~ 2000Hz; 100g, 6ms

Allowed speed

2400 rev / min

Connection cable

1 m shielded cable radial side (rest form can be ordered)

Shape characteristics

Metal shell, sealed double bearing

SSI protocol description

SSI is a synchronous serial signal, two pairs of RS422, one pair of clock trigger, a pair of data transmission.

As shown, the absolute position value of the encoder is triggered by clock signal of the receiving device, from the high bit of Gray code(MSB),output serial signal synchronized with clock signal. The clock signal sent from the receiving device, refer to the total number bits of the encoder, output N interrupt pulse. When the signal is not transmitted, the clock and data bits are high, at the first falling edge of the clock signal, storing the current value, from the rising edge of the clock signal, sending data signal, A clock pulse synchronization a data.

Wherein: t3 is the restore signal, waiting for the next transmission; N = 13; 16; 25; 28. (Total number of digits according to the encoder)

T = 4-11us; t1 = 1-5.5us; t2 ≤ 1us; t3 = 11-15.5us (Clock-and Date-omit not shown).

In actual use, in order to ensure the stability of the signal with the transmission distance farther, recommended the following parameters:

T = 8us (125KHz); t1 = 4us; t2 (the actual reading latency = 3 ~ 4us); t3 = 15us

Data processing

Encoder output is Gray cyclic code, first, receiving device decode it into binary code by XOR way. AS Gray code is cyclic code, there are mutations between maximum code value and 0, therefore, in order to avoid abrupt stroke data, recommended the middle of encoder position data value as the start bit. When the encoder is installed, turn it to the starting position of the actual work, take MIDP core wire short contact to power +, and the current signal is the middle of encoder position data value, then take MIDP wire back to power 0. After the current measured values ​​received into binary code, it should be handled as follows:

The actual position value = (C-MidP) × Dir + starting position value

The above formula, C is the encoder output current measured values​​; MidP is the middle position value , 2n-1, 13 bits is 4096, 16 bits is 32768, 25 bits is 2048 × 8192; 28 bits is 2048 × 65536 . DIR is the direction of rotation of the encoder coefficients, if same to the direction of calculation, defined 1; if opposite, defined -1.

The starting point is not necessarily zero, calibrated by the user to determine their own position, due to multi-turn encoder can have 4096 Circle of continuous measurement, from the start point, both forward and reverse loop continuously working stroke 2048.

Installation dimensions (mm)

Clamping flange (default)

synchro flange

Blind hollow shaft

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