1. Field of the Invention
The invention is related to devices used to couple instruments together for data transmission therebetween and, more particularly to a device for coupling an instrument having an electrical interface and an instrument having an optical interface.
2. Description of the Prior Art
It is well known in the art that analytical instruments and the like are used to capture measurement data. Such data is represented by electrical signals which may easily be manipulated in desired formats. These electrical signals may be in either digital or analog form. Once this data is transformed into electrical signals, it is often desirable to transfer the electrical signals to cooperating instruments to trigger operations by those instruments or for data storage and data manipulation or the like. Such data may be transferred and received electrically by an electrical interface provided between the two instruments.
Some instruments are designed to communicate or otherwise transfer and receive data optically. It is well known in the art that electrical signals may be converted to optical signals and the data representative thereof transferred optically to cooperating instruments. These types of instruments generally communicate through optical interface ports.
Because instruments may have non-compatible communication interface ports, it becomes necessary to provide a communication link adapted for use between such non-compatible interfaces.
For example, such a dilemma has presented itself in the development of some portable gas monitoring systems. In this area of endeavor, federal, state, and local regulations have been implemented which require manufacturers or others handling hazardous materials to monitor potentially hazardous and/or explosive environments about their facilities. In particular, these regulations require periodic monitoring of potential release points such as valves, fittings or the like which pose a potentiality for leakage or emission of substances including toxic, hazardous and/or explosive material. Because some of these affected facilities include intricate piping systems having hundreds of potential release points, sampling of these points becomes quite time consuming and burdensome. As a result, portable monitoring systems have been developed which include a portable hazardous gas analyzer subsystem working in conjunction with a separate portable data collector/processor subsystem for storing data corresponding to concentration values of the hazardous constituents sensed by the gas analyzer at a release point. The data collector/processor subsystem may include a bar code reader to identify a potential release point and include a means of corresponding the identification data with sensed emissions data. A gas monitoring system of this nature is disclosed in U.S. Pat. No. 5,099,437 and is hereinafter incorporated by reference. The gas analyzer subsystem of this monitoring system has an electrical interface, such as a typical RS-232 connector, while the data collector/processor subsystem has an optical interface. Therefore, it becomes necessary to provide a coupling device to facilitate communication between the two instruments having these non-compatible interfaces.
In addition, since these instruments are utilized in potentially hazardous and/or explosive environments, the coupling device must be "intrinsically safe". National standards have been adapted in the United States for "intrinsically safe" equipment, as set forth in the National Electrical Code (NEC). For an instrument to be certified as intrinsically safe, it must be demonstrated that the equipment cannot produce a spark which could cause combustion or produce any other undesired effects in a potentially hazardous environment. An atmosphere having the presence of volatile gases, vapors or flammable liquids are examples of such a potentially hazardous environment. The electrical circuitry in these instruments must not be capable of producing a spark, even if failure of any of the electrical components in the circuitry occurs.
Hence, those skilled in the art have recognized the need to provide an intrinsically safe coupling device to facilitate communication between two instruments, wherein one such instrument has an optical interface and the other instrument has an electrical interface. Such a coupling device should be easily connectable, releasable and cost effective to produce. The present invention meets these needs and others.