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HQ 952101

September 29, 1992

CLA-2 CO:R:C:M 952101 MBR


TARIFF NO.: 8538.90.00

Mr. Jack Flynn
Rudolph Miles & Sons
4950 Gateway East
P.O. Box 11057
El Paso, Texas 79942

RE: Control System Digital Input/Output (I/O) Modules; Parts Of A Control System; Parts Suitable For Use Solely or Principally With The Apparatus Of Heading 8535, 8536 or 8537

Dear Mr. Flynn:

This is in reply to your letter of June 3, 1992, on behalf of the Crouzet Corporation, to the District Director of Customs in El Paso, Texas, requesting classification of control system digital Input/Output Modules, under the Harmonized Tariff Schedule of the United States (HTSUS). Your letter was refered to this office for response.


Digital Input/Output ("I/O") modules are solid state devices which relay on and off electrical signals to and from a computer. Input modules relay either AC or DC voltage converted to a DC logic signal, depending upon the type of module, to a computer or "dumb" system. Output modules work in the opposite direction, switching either AC or DC circuits on or off in response to logic level voltage commands from a computer or "dumb system."

You have submitted a sample part number "Quad Model IAC5Q." A "Quad-pack module" incorporates four electrically identical, single-point circuits in a single, sealed enclosure. The status of each circuit is indicated by one of four LEDs mounted on its top surface. Quad-packs, which are frequently used to conserve space, plug into PB-16Q, PB-16HQ, PB-24Q, PB-24HQ, PB-32Q, and PB-32HQ digital I/O module mounting boards.


What is the classification of a "Quad-pack" digital Input/Output Module, under the Harmonized Tariff Schedule of the United States (HTSUS)?


The General Rules of Interpretation (GRI's) to the HTSUS govern the classification of goods in the tariff schedule. GRI 1 states, in pertinent part:

...classification shall be determined according to the terms of the headings and any relative section or chapter notes...

Information obtained by my staff from personnel at the Crouzet Corporation, indicates that these digital I/O modules are used almost exclusively in "industrial control systems," that they control the flow of electricity, and that they are analogous to relays. They are controlled either by an intelligent control system (computer) or a "dumb" system (such as indication whether a door is open or closed).

You argue that the section XVI Harmonized Commodity Description System Explanatory Notes (ENs) to chapter 84, p. 1298, "appear to correctly describe the input/output units of which the input/output modules are an integral part [in chapter 84]." However, the ENs are in fact describing input units for ADP machines such as keyboards, and output units such as ADP display CRTs and printers.

The digital I/O modules are parts of industrial control systems, and as such are not "specifically designed as part of such a [ADP] system," as required by chapter 84, Legal Note 5(B)(b), HTSUS. See HQ 950126, dated November 15, 1991, for a similar holding regarding similar merchandise.


The "Quad Model IAC5Q" digital Input/Output modules are a part of a control system, classifiable in subheading 8538.90.00, HTSUS, which provides for: "[p]arts suitable for use solely or principally with the apparatus of heading 8535, 8536 or 8537: [o]ther."


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