Name: RF28 Reflective Optical Encoder Module
Brand: EPOCH
SKU: RF28
Price: Contact for quote USD
Availability: InStock

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Quick Select: Mechanical Drawings Features Tech Specs Waveform Pin Definition Ordering Guide FAQ

RF28 Mechanical Dimension Drawing — 28mm Reflective Optical Encoder Module Footprint (Ø28.9 x 18.2 mm)

RF28 Series — Mechanical Dimension Drawing

RF28 Mechanical Dimension Drawing

RF28 Mechanical Dimension Drawing

Ø28.9 mm overall diameter, 18.2 mm height. Unit: mm.

Motor End Face & Shaft Dimensions — RF28 Reflective Encoder Module

RF28 Dimensions Of Motor End Face and outgoing shaft length

[FEATURES] RF28 Series Reflective Optical Encoder Module — Key Features & Description

•

Type: 28mm reflective optical encoder module

•

Resolution: 500 ~ 8,000 CPR, 3-channel differential

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Output: A, A/, B, B/, Z, Z/ differential

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Z Signal: Selectable 90°, 180°, or 360° (standard 90°)

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Supply: 3V ~ 5V DC

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Max Speed: 11,000 RPM

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Temp: -40°C ~ +85°C

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Design: PCBA+code disc, no bearing

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Size: Ø28.9 mm x 18.2 mm

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Plug: SHR-09V-S

RF28 Technical Specifications — 500~8000 CPR 3-Channel Differential Reflective Optical Encoder Module

Parameter	Specification
Technology	Reflective optical encoding with PCBA and code disc
Output Signals	A, A/, B, B/, Z, Z/ (differential)
Resolution Range	500 ~ 8,000 CPR
Supply Voltage	3V ~ 5V DC
Max Mechanical Speed	11,000 RPM
Operating Temperature	-40°C ~ +85°C
Shaft Diameter Options	2mm, 3mm, 4mm, 5mm, 6mm, 1/8in, 5/32in, 3/16in, 1/4in
Plug Connector	SHR-09V-S (9-pin)

Output Waveform Diagram — RF28 Reflective Optical Encoder Module 3-Channel Differential Timing

RF28 Series Output Waveform Diagram

RF28 Series Output Waveform

Waveform shown for counterclockwise rotation, viewed from the encoder toward the motor body.

3-channel differential (A, A/, B, B/, Z, Z/), 90° phase shift A-B. Z selectable 90°/180°/360°.

Pin Definition — RF28 Reflective Optical Encoder Module (9-Pin, SHR-09V-S Plug)

Line Number	1	2	3	4	5	6	7	8	9
Identification number A defines	Vcc	Gnd	A	A/	Z	Z/	N.C.	B	B/
Identification number B defines	Vcc	Gnd	A	A/	B	B/	Z	Z/	N.C.

Plug recommended: SHR-09V-S

Ordering Information / Part Number Code — RF28 Reflective Optical Encoder Module

R

→

F

→

2

→

8

→

CPR Code

→

Shaft Dia. Code

→

ID Code

Series Prefix

e.g. A=500, R=4096

e.g. 01=2mm, 11=4mm

e.g. A=Std, B=ID B

CPR Code	A	I	B	J	T	U	W	N	R	Z	8K
CPR	500	512	1,000	1,024	2,000	2,048	2,500	4,000	4,096	5,000	8,000

Shaft Code	01	02	03	04	05	06	11	12	14
Diameter	2 mm	3 mm	1/8 in	5/32 in	3/16 in	1/4 in	4 mm	6 mm	5 mm

ID Code	A	B
Definition	Identification number A (Same as A by default)	Identification number B

Example Ordering Code:

RF28B14A

= RF28 Series · B=1000 CPR · 14=5mm shaft · A=Standard ID

Module Printing / Label — RF28 Reflective Optical Encoder Module

RF28 Module Printing / Label

RF28 Model Print

Module printing includes model code, CPR rating, shaft diameter, and ID code as per ordering code format.

Technical FAQs — RF28 Reflective Optical Encoder Module

Q: RF28 reflective encoder vs HEDS-9000 transmissive module — what is the key difference for servo motor feedback?

The RF28 reflective optical encoder module uses a PCBA+code disc design without a separate light source aperture, making it approximately 40% thinner than transmissive modules like the HEDS-9000 series. The RF28 delivers 500~4,096 CPR in 3-channel differential format (A, A/, B, B/, Z, Z/) at up to 11,000 RPM, with a selectable Z-signal width of 90°, 180°, or 360°. This reflective design eliminates the through-slot alignment required by transmissive encoders, simplifying mechanical integration into compact DC and stepper motor assemblies.

Q: What CPR resolution do I need for a small DC servo motor, and can the RF28 encoder module support it?

For small DC and stepper motor feedback applications, 500 to 2,048 CPR is the most common range, and the RF28 reflective encoder module covers this with 11 selectable resolution codes from 500 CPR (code A) up to 8,000 CPR (code 8K). For higher precision needs, the ordering code also supports 8,000 CPR (code 8K). The 3-channel differential output ensures signal integrity over longer cable runs, making the RF28 suitable for industrial servo motor position loops requiring reliable A, A/, B, B/, Z, Z/ feedback at 11,000 RPM maximum mechanical speed.

Q: Does the RF28 28mm reflective encoder fit 1/4-inch and 6mm motor shafts?

Yes, the RF28 reflective encoder module supports 9 shaft diameter options including 6mm (code 12) and 1/4in (code 06); the RF28 supports 9 shaft diameter options from 2mm to 1/4in, and 1/4-inch (code 06). The full shaft code range covers 2mm (01), 3mm (02), 4mm (11), 5mm (14), 6mm (12), 1/8in (03), 5/32in (04), 3/16in (05), and 1/4in (06). The 28mm housing diameter with PCBA+code disc design accommodates a wide range of small motor shaft sizes without requiring additional adapters or machining.

Q: Why does a reflective encoder like RF28 eliminate the Z-pulse alignment issues common in through-slot encoder designs?

Reflective encoders like the RF28 integrate the light source and detector on the same side of the code disc, eliminating the through-beam alignment sensitivity that transmissive encoders (e.g., HEDS-9000, AEDS-962x) suffer from. This means the Z-index pulse timing remains stable across temperature (-40°C to +85°C operating range) and vibration, with selectable pulse widths of 90°, 180°, or 360° electrical degrees. The RF28 differential output (A, A/, B, B/, Z, Z/) also provides common-mode noise rejection that preserves Z-pulse integrity in electrically noisy motor environments.

Q: Can I use the RF28 as a drop-in replacement for the HEDS-9100 or AEAT-6600 in motion control applications?

The RF28 reflective encoder module offers the same 3-channel differential output format (A, A/, B, B/, Z, Z/) as the HEDS-9100 and AEAT-6600 series, with an SHR-09V-S 9-pin connector interface. However, the RF28 uses a reflective PCBA+code disc design rather than transmissive optics, so it requires a different mechanical mounting approach. Key parameters to verify for drop-in replacement: 28mm housing diameter (Ø28.9 x 18.2 mm), 3V~5V supply voltage, and the 9-pin wiring identification (two configurable pinouts — ID A and ID B — are provided in the datasheet). Contact EPOCH for a compatibility assessment for your specific motor platform.

[CROSS-REFERENCE] Need an Ultra-Compact 20mm Form Factor?

RF20 Ultra-Compact Reflective Optical Encoder Module — Smaller 20mm footprint (13.0 x 20.2 mm) for space-constrained applications. Shares the same 3-channel differential output and selectable Z signal as the RF28 reflective encoder module.

RF28 Encoder Sourcing

Request a Quote

Need custom resolution, shaft diameter, or bulk pricing for the RF28 reflective optical encoder module? Contact our sales team.

Request Direct Sourcing Evaluation →

Sales: liya@epoch-electronic.com

Legal Disclaimer: All manufacturer names and trademarks referenced are for cross-compatibility reference only. EPOCH is an independent manufacturer with no affiliation to OEM brands.