United States International Trade Commision Rulings And Harmonized Tariff Schedule
faqs.org  Rulings By Number  Rulings By Category  Tariff Numbers
faqs.org > Rulings and Tariffs Home > Rulings By Number > 2001 HQ Rulings > HQ 964505 - HQ 964603 > HQ 964599

Previous Ruling Next Ruling
HQ 964599

DECEMBER 22, 2000

CLA-2 RR:CR:GC 964599 JAS


TARIFF NO.: 8543.89.40

Mr. Ronald P. Ricca
Allen-Bradley/Rockwell Automation
1 Allen-Bradley Drive
Mayfield Heights, OH 44124-6118

RE: HQ 962138 Modified; Optical Encoders

Dear Mr. Ricca:

In HQ 962138, which we issued to you on July 28, 1999, certain optical encoders were held to be classifiable in subheading 9029.10.80, Harmonized Tariff Schedule of the United States (HTSUS), as other revolution counters.

Pursuant to section 625(c), Tariff Act of 1930 (19 U.S.C. 1625(c)), as amended by section 623 of Title VI (Customs Modernization) of the North American Free Trade Agreement Implementation Act, Pub. L. 103-182, 107 Stat. 2057, 2186 (1993), notice of the proposed modification of HQ 962138 was published on November 15, 2000, in the Customs Bulletin, Volume 34, Number 46. Two comments were received in response to the notice, yours and another which opposed the proposal.

You opposed the proposed modification on the basis of website materials that refer to optical encoders as devices that measure both distance and linear and rotary motion. While you apparently agree with our statement that the encoders convert shaft rotations into electrical pulses, you state this is incidental to their principal function of determining distance. You conclude that all measuring devices are classifiable in Chapter 90, HTSUS, and that relevant legal notes exclude from heading 8543, HTSUS, articles of Chapter 90. For the reasons expressed in this ruling, we continue to believe that the optical encoders at issue do not actually count the revolutions of a rotating shaft; rather, they convert shaft rotations to electric pulses. Computer software not associated with the encoders detects and counts these pulses to yield the required positional data.


The articles at issue here were identified in HQ 962138 as Bulletin 845A, B, and C industrial electrical output. The 845D was described as a single turn Absoulte Position Encoder that digitizes shaft angle position into one of a number of absolute code formats. On the outer edge of a coded disk built into the encoder are a number of slots that allow light to pass through. The encoder utilizes a single laser diode and fiber optic module to produce a concentrated beam of light. As the disk rotates, a photoelectric sensor in the encoder 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.

Initially, PC 861139 classified the encoders in subheading 8543.80.40 (now 89.40), HTSUS, a provision for electric synchros and transducers. In undertaking this reconsideration, HQ 962138 noted that PC 861139 merely listed the items and the applicable classification subheadings, and provided no reasoning. With respect to the encoders, it was noted that aside from the descriptions you provided, there was no information about their principal function or use. 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. For the reasons that follow, we believe that the correct subheading for these encoders is 8543.89.40, HTSUS. We regret the delay in resolving this matter and any resulting confusion.

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 the Bulletin 845 series 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.

The Harmonized Commodity Description and Coding System Explanatory Notes (ENs) constitute the official interpretation of the HTSUS. Though not dispositive, the ENs provide a commentary on the scope of each heading of the HTSUS. Customs believes the ENs should always be consulted. See T.D. 89-80. 54 Fed. Reg. 35127, 35128 (Aug. 23, 1989).

Heading 8543 is in Section XVI, HTSUS. Note 1(m) to Section XVI excludes articles of Chapter 90. Therefore, if the encoders at issue here are articles of heading 9029, or of any other heading of Chapter 90, they cannot be classified in heading 8543 or elsewhere in Chapter 85. The heading 9029 ENs, on p. 1646, under the general heading (A) COUNTING DEVICES, describe (1) Revolution counters as follows:

These instruments count the number of revolutions of a mechanical part (e.g., machine shaft). They consist mainly of a driving spindle geared to pointer or drum indicators. They usually have a device for re-setting the counter to zero. The counters may be coupled to the revolving part either directly (in some cases the part drives the gearing itself) or by remote control. The driving spindle may be operated by a rotary, alternating or pulsating movement of the turning part (e.g., encoders).

Also, the 9029 ENs, on p. 1647, describe (B) SPEED INDICATORS AND TACHOMETERS as:
instruments that differ from the revolution counters of Part (A) in that they indicate the number of revolutions, speed, output, etc., per unit of time (e.g., revolutions per minute, miles per hour, kilometers per hour, meters per minute. Utilizing a clock or watch movement together with a measuring mechanism, tachometers measure rotational speed by dividing the absolute number of rotations by the elapsed time.

These ENs suggest that revolution counters count the number of shaft rotations while tachometers measure angular speed. With respect to revolution counters, the encoders at issue lack the driving spindle and the pointer or drum indicators, or their electronic equivalent, referenced in the ENs. Because they are not actually counting shaft rotations or keeping the count, they also lack a device for resetting the counter to zero. The encoders at issue merely convert shaft rotations to electric pulses in the form of positional information data about, for example, where a shaft is in its rotation cycle. This is data which the encoders send, through an interface, to any one of a number of computers, control systems, or other instrumentation. The following quoted phrase appears in material from an electronic website of Rice University which you provided in response to our request for comments “The light pulses created by the turning wheel can be detected and counted with special software to yield rotation or distance data.” (Underlining added). It is apparent that the referenced software that does the “counting” is in the computer that the encoder’s output is connected to, not in the encoder itself. We remain of the opinion that these encoders are transducers which convert shaft
rotations into an output of electric pulses. They are analogous to a device, useful to the blind, which would ring a bell each time a slowly rotating shaft completes a revolution. By converting the rotation to a pulse of sound, there would now be information the blind could use, but someone would still have to do the counting and speed determination. The optical encoders at issue are not within the EN description either for rotation counters or for tachometers.

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 Bulletin 845A, 845B and 845C industrial optical encoders are provided for in heading 8543. They are classifiable in subheading 8543.89.40, HTSUS.


HQ 962138, dated July 28, 1999, is modified as to this merchandise. In accordance with 19 U.S.C. 1625(c), this ruling will become effective 60 days after its publication in the Customs Bulletin.


John Durant, Director
Commercial Rulings Division

Previous Ruling Next Ruling

See also: