HB6M Hollow Bore Optical Encoder

HB6M Features

  • Hollow bore (hollow shaft/thru-bore) bearing design
  • Rugged anodized aluminum housing
  • Heavy-duty ball bearings track up to 6,000 RPM
  • Positive latching polarized connector
  • 2-channel quadrature with optional index
  • Multiple Output Drive Options
  • 64 to 10,000 cycles per revolution (CPR); 256 to 40,000 pulses per revolution (PPR)

See more info below

Configure the HB6M

HB6M Product Description

Restriction of Hazardous Substances

The HB6M is a high-resolution hollow bore (hollow shaft/thru-bore) optical encoder with a machined aluminum enclosure and an anodized protective finish. The HB6M optical incremental encoder is designed to easily mount to an existing shaft to provide digital feedback information. Typical applications include motor feedback, process control, robotics, textile machines, and elevator controls.

The HB6M bearing style encoder features a hollow bore that accepts shaft diameters from 0.236 in. to 0.750 in. in diameter. The encoder slips over the shaft and is locked into place with two 6-32 set screws. A flexible anti-rotation mount makes the encoder more tolerant of shaft runout than a standard kit encoder. The HB5M can accommodate shaft axial play up to ±0.030 in. and shaft runout up to 0.010 in. The flexible tether provides single-point mounting for bolt circle diameters from 2.5 in. to 5.0 in.

The HB6M housing comes standard with a closed cover or an optional hole in the body to allow a shaft to pass completely through the encoder.

A secure connection to the HB6M Series encoder is made through a 5-pin (single-ended versions) or 10-pin (differential, high-voltage or open-collector versions) latching connector. The mating connectors are available from US Digital with several cable options and lengths.

Product Specifications


Operating Temperature (CPR < 3600) -40 to 100 C
Operating Temperature (CPR ≥ 3600) -25 to 100 C
Electrostatic Discharge 
Single-ended (-S version), IEC 61000-4-2
Differential (-D version), Human Body Model
High-Voltage, Open-collector (H, C option), IEC 61000-4-2

± 4
± 2
± 4
Vibration (10Hz to 2kHz, sinusoidal) 20 G
Shock (6 milliseconds, half-sine) 75 G


Max. Acceleration 100000 rad/sec²
Max. Shaft Speed 6000 rpm
Max. Starting Torque 0.70 oz-in
Max. Bore Loading 5 lb.
Weight 11.5 oz.
Max. Shaft Runout 0.010 in. T.I.R.
Max. Shaft Axial Play ± 0.030 in.
Required Shaft Length (From mounting surface) Min. = 0.3 in.
Max. = 1.4 in. with default cover.
Max. = No limit with H-option cover.
Moment of Inertia 3.7x10^-3 oz-in-sec²
Technical Bulletin TB1001 - Shaft and Bore Tolerances Download


The tether is shipped detached and may be mounted in the four different methods as shown below.


A leads B in a clockwise shaft rotation, and B leads A in counterclockwise shaft rotation viewed from the rear side (opposite flexible mount) of the encoder.


  • S option provides 5V TTL compatible outputs
  • Specifications apply over the entire operating temperature range
  • Typical values are specified at Vcc = 5.0Vdc and 25°C
  • For complete details, see the EM1 and EM2 product pages
Supply Voltage 4.5  5.0 5.5 V  
Supply Current   27 33 mA CPR < 1000, no load 
  54 62 mA CPR ≥ 1000 and < 3600, no load
  72 85 mA CPR ≥ 3600, no load
Low-level Output     0.5 V IOL = 8mA max., CPR < 3600
    0.5 V IOL = 5mA max., CPR ≥ 3600
  0.05   V no load, CPR < 3600
  0.25   V no load, CPR ≥ 3600
High-level Output 2.0     V IOH = -8mA max., CPR < 3600
2.0     V IOH = -5mA max., CPR ≥ 3600
  4.8   V no load, CPR < 3600
  3.5   V no load, CPR ≥ 3600
Output Current Per Channel -8   8 mA CPR < 3600
-5   5 mA CPR ≥ 3600
Output Rise Time   110   nS CPR < 3600
  50   nS CPR ≥ 3600
Output Fall Time   35   nS CPR < 3600
  50   nS CPR ≥ 3600


  • D Option provides differential line driver output
  • Specifications apply over the entire operating temperature range
  • Typical values are specified at Vcc = 5.0Vdc and 25°C
  • For complete details, see the EM1 and EM2 product pages
Supply Voltage 4.5 5.0 5.5 V
Supply Current   29 36 mA CPR < 1000, no load 
  56 65 mA CPR ≥ 1000 and < 3600, no load
  74 88 mA CPR ≥ 3600, no load
Low-level Output   0.2 0.4 V IOL = 20mA max.
High-level Output 2.4 3.4   V IOH = -20mA max.
Differential Output Rise/Fall Time     15  nS  


  • H option uses a higher supply voltage and provides both single-ended and open-collector outputs
  • Single-ended outputs are 5V TTL compatible (same as S option)
  • Specifications apply over the entire operating temperature range
  • For complete details, see the EM1 or EM2 product pages
Supply Voltage 7.5   30.0 V  
Supply Current, 24V power   8 10 mA CPR < 500, no load
  16 19 mA CPR ≥ 500 and < 2000, no load
  22 25 mA CPR ≥ 2000, no load
Open Collector "On" Resistance   2   ohms  
Open Collector Sink Current     200 mA  
Output Low Voltage     0.4 V 200 mA sink current
Open Collector Pullup Voltage     50 V  



Pin Description Pin Description
1 Ground 1 Ground
2 Index 2 Ground
3 A channel 3 Index-
4 +5VDC power 4 Index+
5 B channel 5 A- channel
    6 A+ channel
    7 +5VDC power
    8 +5VDC power
    9 B- channel
    10 B+ channel


Pin Description
1 Ground
2 Ground
3 Index- (open collector)
4 Index+ (single-ended)
5 A- channel (open collector)
6 A+ channel (single-ended)
7 7.5-30V power
8 7.5-30V power
9 B- channel (open collector)
10 B+ channel (single-ended)


(1) 5-pin single-ended mating connector is CON-FC5.
(2) 10-pin differential mating connector is CON-FC10.


Title Date Description Download
HB5M, HB6M & HD25 - PCN 7315 5/17/2023 As part of our ongoing continuous improvement efforts, we are updating our HB5M, HB6M and HD25 series of optical encoders to make product labeling clearer and permanent. The aluminum housing of these encoders will now be anodized black, and labeling will be laser etched onto the surface, providing more contrast and legibility. Previously pin-outs were machined into the housing and product labeling was printed onto an adhesive label that was placed on the side of the product. Product labeling will also now appear on the top surface of the encoder near the pin-out labeling. Download
EM1 LED Die - PCN 1016 2/7/2013 As part of US Digital's continual assurance of supply strategy, we have qualified additional sources for our LED die used in our EM1 encoder module, which in turn impacts all of the following products:

EM1, E2, E3, E5, E6, H1, H15, H3, H5, H6, HB5M, HB6M, HD25, PE, S1, S2, S5, S6, T5 and T6

The device specification will remain the same, i.e. there will be no change to form, fit or function of the product(s) as specified by US Digital. The appropriate quality and reliability testing has been performed on representative products to ensure normal parametric distribution, consistent with US Digital's quality and reliability standards.
EM1 & EM2 Update - PCN 4199 1/14/2014 Based on our continuous process improvement program, US Digital is changing the current marking method for our EM1 and EM2 encoder modules to a serialization method. This change will allow for each module to have a unique code; the current marking method is based on a date code system that includes all encoder modules produced within a specific week / year. The serialization system will be based on a hexadecimal system. 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.


Assembly Instructions


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