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HQ 963802

JANUARY 10, 2001

CLA-2 RR:CR:GC 963802 JAS


TARIFF NO.: 8543.89.40

Ms. Barbara Stegeman
Wilson International, Ltd.
6725 Airport Road, Suite 101
Mississauga, Ontario, Canada L4V1V2

RE: Absolute and Incremental Encoders

Dear Ms. Stegeman:

In your letter of January 26, 2000, on behalf of TR Controls, Inc., you inquire as to the classification, under the Harmonized Tariff Schedule of the United States (HTSUS), of encoders, products of Germany. Descriptive literature was submitted. You indicate that a local Customs officer tentatively advised you that a provision in heading 9028, HTSUS, for revolution counters and the like, might apply. HQ 962138, dated July 28, 1999, was cited as authority. We regret the delay in responding.


The merchandise at issue is described as absolute encoders and incremental encoders. These are devices that attach to rotary shafts in machine tools, handling and packaging robots, and printing machinery, among other industrial uses, to detect and measure angular and rotary motion. The encoders utilize a laser diode and an optical module to convert rotating mechanical movement to electrical signals in the form of pulses which are transmitted to and read by a control system. On the outer edge of a coded disk built into the encoders are a number of slots that allow light to pass through. The encoders utilize a single laser diode and fiber optic module to produce a concentrated beam of light. As the disk rotates, a photoelectric sensor in the encoders senses the light as it appears through the slots. Each time the light appears a pulse is generated. Electronic circuitry within the optical encoders designed to convert mechanical
rotary motion to an accurate encoder converts the pulses into a usable data format which a computer or control systems reads by means of an interface module.

The HTSUS provisions under consideration are as follows:

8543 Electrical machines and apparatus, having individual functions, not specified or included elsewhere in [Chapter 85]:

8543.89 Other:

Electric synchros and transducers



Revolution counters, production countersand the like:

9029.10 Revolution counters, production countersand the like:

9029.10.80 Other


Whether absolute encoders and incremental encoders are revolution counters of heading 9029.


Under General Rule of Interpretation (GRI) 1, Harmonized Tariff Schedule of the United States (HTSUS), goods are to be classified according to the terms of the headings and any relative section or chapter notes, and provided the headings or notes do not require otherwise, according to GRIs 2 through 6. Chapter 90, Note 2(a), HTSUS, states, in part, that parts and accessories which are goods included in any heading of Chapter 90, or of Chapter 84, 85 or 91 (other than heading 8485, 8548 or 9033) are in all cases to be classified in their respective headings. Note 2(b) states, in part, that other parts and accessories are classifiable with the machines, instruments or apparatus with which they are solely or principally used.

On the basis that a certain number of pulses generated equated to one complete rotation of the shaft, HQ 962138 concluded that the encoders performed the function of revolution counters described by heading 9027, HTSUS. However, that ruling was modified as to optical encoders by HQ 964599, dated December 22, 2000, the principles of which are incorporated by reference in this decision. For the reasons that follow, we are of the opinion that these encoders are provided for in heading 8543, HTSUS, as electrical machines and apparatus, having individual functions, not specified or included elsewhere in Chapter 85.

The term transducer encompasses devices which convert variations in one energy form into corresponding variations in another, usually electrical form. Among these is the velocity transducer in which the velocity of rotating shafts can be measured by an optical encoder with a suitable light source and detector. By choosing an appropriate pattern, the output data can be produced in binary form suitable for direct input to a computer system. Optical encoders come in two kinds, absolute encoders and incremental encoders. The absolute encoder is a position transducer with output in the form of parallel binary digits. See McGraw-Hill Encyclopedia of Science & Technology, Vol. 18, pp. 459-462 (6th ed., 1987).

Heading 8543 covers all electrical appliances and apparatus not falling in any other heading of Chapter 85, nor covered more specifically by a heading of any other chapter of the HTSUS, or excluded by a legal note to Section XVI or to Chapter 85. The cited technical source indicates that optical encoders are a type of velocity transducer. While not conclusive, we note that subheading 8543.89.40 specifically provides for electric synchros and transducers. Notwithstanding the fact that optical encoders might function as parts of larger instrumentation systems, they are goods included in heading 8543, in accordance with Chapter 90, Note 2(a), HTSUS.


Under the authority of GRI 1, the absolute encoders and incremental encoders are provided for in heading 8543. They are classifiable in subheading 8543.89.40, HTSUS.


John Durant, Director
Commercial Rulings Division

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