ESUM Two Encoder to One Encoder Adder/Subtractor

ESUM Features

  • Fast hardware solution
  • Obtains sum or difference of 2 encoder positions
  • DIN rail mount option

See more info below

Configure the ESUM

The ESUM is no longer available for purchase.

ESUM Product Description

The ESUM combines the quadrature outputs of two encoders into a single quadrature output. The output quadrature may be selected to be either the sum or difference of the two quadrature inputs. The index from encoder 0 is simply wired to the index of the output. The index from Encoder 1 is not used. Connectors are 5-pin positive latching.

Applications for the ESUM include:

  • Coarse and fine operator controls when one encoder is high resolution and the other is low resolution.
  • Measuring the difference in position between 2 shafts with one encoder is mounted on each.
  • Measuring dynamic coupling twist with one encoder mounted on each side of the coupling.

The ESUM functions by sampling the two encoder inputs, decoding the quadrature inputs into up/down signals, combining the up/down signals, and synthesizing new quadrature on the output. The sampling nature of the operation limits the maximum quadrature frequency to 46.8 kHz.

To use, simply place the ESUM in-line with the encoder cables. The ESUM derives its power from the +5V pin of the encoder cable. DIN rail mounting is available. Only SW1 effects the function of the ESUM. SW2, SW3 and SW4 are not used.

Product Specifications

View here or download the specifications

Absolute Maximum Ratings

Storage Temperature -40 100 C
Operating Temperature 0 70 C
Humidity (non-condensing) 0 95 %
Digital Inputs (diode clamped) -0.6 5.6 V


Supply Voltage (Vcc) 4.75 5.0 5.25 V
Supply Current (no encoders)   120   mA
Input Low Voltage 0   0.8 V
Input High Voltage 2.0   Vcc V
Output Low (8 mA current sink)     0.4 V
Output High (4 mA current source) 2.4     V
Max. Input Frequency     46.8 kHz
Max. Phase Delay     40 usec.


Encoder 0 Input:

1 Ground
2 Index
3 A channel
4 +5V out (direct connection to pin 4 of Output connector)
5 B channel

Encoder 1 Input:

1 Ground
2 Index (value ignored)
3 A channel
4 +5V out (direct connection to pin 4 of Output connector)
5 B channel

Encoder Output:

1 Ground
2 Index
3 A channel
4 +5V input
5 B channel

DIP Switch Settings

1 switch down = sum (Encoder 0 + Encoder 1)
switch up = difference (Encoder 0 - Encoder 1)
2 no function
3 no function
4 no function

Product Change Notifications

Title Date Description Download
PCN 1011 9/21/2011 The AD2B, AD4B, AD7, EADAPT, EDAC2, EDIVIDE, EPOT, EQUAD, ESUM, ESWITCH, ETACH2, SEI-USB, USB-232 currently utilizes a printed thermal transfer label. This label will no longer be used and will be replaced by laser marking directly onto the housing of the product. The purpose for this change is to create a more durable solution, and eliminate the possibility of the label being inadvertently removed from the housing. Download

Additional Information

Product Notes

  • Cables and connectors are not included and must be ordered separately.
  • US Digital® warrants its products against defects in materials and workmanship for two years. See complete warranty for details.

Downloads Available


3D Model Downloads

Please configure your product first to download a 3D model.
(Note: The formats below will become links if there are 3D models available.)

    • SolidWorks format
    • IGES format
    • Parasolid format
    • STEP format

    Product Configurator

    This product is no longer configurable or available for new applications.


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