Electrical connectors – Alternatively connected – Coupling part
Reexamination Certificate
1998-08-18
2001-02-20
Nguyen, Khiem (Department: 2839)
Electrical connectors
Alternatively connected
Coupling part
C439S502000
Reexamination Certificate
active
06190190
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is directed to digital communications and, particularly, to connectors for providing serial communications between digital devices.
When providing serial connections between digital devices (“DDs”), it is sometimes appropriate to connect the transmit (“Tx”) pin of one DD to the receive (“Rc”) pin the other DD and to connect the receive Rc pin of the first DD to the Tx pin of the other DD. This is called a “null modem pin-through” and is typically required, for example, when coupling two computers to one another.
In other instances, it is necessary to connect the Tx pin of the first DD to the Tx pin of the other DD and to connect the Rc pin of the first DD to the Rc pin of the modem. This is typically called a “straight pin-through” and is typically required when one of the DDs is a modem or other such communications device.
Most DDs are provided with an industry-standard serial port, the most common of which is the RS-232 port. This is a 9-pin connector adapted to receive a matching plug. To avoid confusion, the RS-232 port (and other industry standard ports) have a definite “sense,” meaning that they mate with corresponding plugs only when the plug and port are oriented in the same direction.
This can be highly convenient, e.g., when connecting a modem to a computer using a standard “serial cable”—that is, a cable with RS-232 plugs wired such that the respective Tx pins are directly connected with one another and, likewise, such that the respective Rc pins of the plugs are directly connected with one another.
However, it can be highly inconvenient when attempting to connect two computers to one another. In this instance, a special adaptor—referred to as a null-modem adaptor—must be utilized effectively to reverse the Tx and Rc pins of one of the DDs. Alternatively, a special cable must be wired, called a null-modem cable, in which the wires connecting the Tx and Rc pins are crossed.
In view of the foregoing, there exists a need for a serial connector which is capable of attaching all types of DDs to one another, regardless of whether the Tx and Rc pins on one DD are to be directly connected to the Tx and Rc pins, respectively, on another DD; or whether the Tx and Rc pin connections are to be reversed.
SUMMARY OF THE INVENTION
The present invention addresses the foregoing needs by using a reversible plug and socket combination for serial communications. When the plug is connected to the socket at one orientation, e.g., the “modem” orientation, the plug and socket can be used to connect DDs that require a straight pin-through connection. On the other hand, when the plug is reversed to connect to the socket at another, different orientation, e.g., the “terminal” orientation, the plug and socket can be used to connect DDs that require a null modem pin-through connection.
In this regard, the plug and socket each have two, and preferably three, conductors that are brought into electrical contact when the plug and socket are mated. For example, the plug may have a Tx prong, an Rc prong, and a Ground prong, while the socket may have a Tx sleeve, an Rc sleeve, and a Ground sleeve.
When the plug and socket are mated in the modem orientation, the Tx prong and sleeve come into electrical contact; the Rc prong and sleeve come into electrical contact; and the Ground prong and sleeve come into electrical contact. When mated in the terminal configuration, the Tx prong comes into electrical contact with the Rc sleeve; the Rc prong comes into electrical contact with the Tx sleeve; and the Ground prong and sleeve come into electrical contact. Where only two conductors are provided on the plug and socket, no Ground prong or sleeve is provided.
Thus, the plug and socket can be used to provide either straight pin-through or null modem pin-through connections. For example, if one end of a serial cable is connected to one DD, e.g., via a conventional RS-232 plug/socket combination, the other end of the serial cable can be provided with a reversible plug of the type described herein for mating—in either the “modem” or “terminal” orientations—with a socket as described above. As a result, it is possible to use the same cable to connect a DD to a modem or to another DD, merely by switching the orientations of the plug (e.g., by flipping it). In this manner, the invention eliminates the need for a specialized modem adaptor or similar specialized hardware.
In preferred aspects of the invention, the reversible plug and/or socket are labeled to indicate their respective orientations. For example, wording and/or arrows may be used to indicate the orientation of the plug, i.e., whether it is in the modem orientation or the terminal orientation.
In the discussion that follows, modems and other DDs that require a straight pin-through when attached for serial communications with a computer are collectively referred to as “modems.” Computers and other DDs that require a null modem pin-through when attached for serial communications with other computers are collectively referred to as “DDs.”
This brief summary has been provided so that the nature of the invention may be understood quickly. A more complete understanding of the invention can be obtained by reference to the following detailed description of the preferred embodiment thereof in connection with the attached drawings.
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Boutin Michael
Daly Thomas
Duverne J. F.
Nguyen Khiem
Nutter & McClennen & Fish LLP
Powsner David J.
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