Electrical computers and digital data processing systems: input/ – Intrasystem connection – Bus access regulation
Reexamination Certificate
2000-03-08
2001-10-09
Dharia, Rupal (Department: 2181)
Electrical computers and digital data processing systems: input/
Intrasystem connection
Bus access regulation
C710S120000, C710S062000, C710S063000, C710S104000, C439S189000, C439S497000, C326S030000
Reexamination Certificate
active
06301633
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a serial interface and more particularly to a generic interface that is automatically configurable for operation with different physical interfaces in either a data terminal equipment (DTE) mode or a data circuit terminating equipment (DCE) mode.
There are 12 primary serial interfaces currently used in industry. These interfaces include Electronics Industry Association/Telecommunications Industry Association (EIA/TIA) EIA/TIA-232, EIA/TIA-449, EIA/TIA-530, and EIA/TIA-530A. These interfaces are also well known in the industry under the former EIA prefix “RS-” as RS-232, RS-449, RS-530, and RS-530A. Additional interfaces include International Telecommunications Industry (ITU) X.21 and V.35.
Each interface standard defines electrical characteristics of the serial signals, the number of interface pins and how the pins are connected to the interface signals. Each serial interface operates either as a DTE or as a DCE. A terminal or computer is typically referred to as the DTE and a modem is typically referred to as the DCE. A signal that is an output on a DTE is the input to the DCE on the opposite end of the serial interface. The DCE is the clock master when communicating to the DTE.
Network Processing Nodes (NPNs), such as routers, modems and network servers, might use different serial interfaces. A different serial cable and different serial interface circuitry is required to connect together each different combination of serial interfaces on two NPNs. Since there are so many different serial interfaces, many different serial cables, connectors and interface circuits are needed. Selecting and installing the right cable is difficult since the operator often does not know the specific serial interface used on each NPN.
Instead of supporting multiple serial cables, a NPN could support one generic serial interface which would be a super set of all other serial interfaces. The generic interface would use a generic connector which would connect to a transition cable which would then connect to the specific interface.
Existing generic serial interfaces include a generic connector on a first end of a transition cable. A second end of the cable includes a connector that conforms to one of the serial interface standards. However, these generic interfaces use a large number of different signals and as a result require a large connector with a large number of pins. Therefore, the generic interface circuitry used for configuring the large number of signals on the generic interface to different serial interfaces is also complex. Moreover, some generic serial interface cables include resistors in the cable which add cost and lower reliability.
Accordingly, a need remains for a generic serial interface that uses fewer generic signals and, in turn, fewer connector pins and less complex interface circuitry.
SUMMARY OF THE INVENTION
A generic serial interface includes one of a variety of different transition cables each having a first interface at a first end including a connector conforming to one of several different serial interface standards. The transition cable provides a mode signal that identifies the type of serial interface. A second end of the cable includes a generic interface having a generic connector that remains the same for each different transition cable. The generic interface is assigned a unique set of generic signals that are connected to associated signals on any one of the different interfaces that may exist on the opposite end of the cable.
An interface circuit is coupled to the generic connector and is automatically reconfigured according to the type of interface associated with the transition cable. The interface circuit includes a termination resistor array that is selectively connected to different data and clock signals according to the types of cable interface. The termination resistor array in combination with the novel assignment of generic signals allow the generic interface to be compatible with all commonly used interfaces both in DCE and DTE modes while using substantially fewer connector pins and simpler interface circuitry than existing generic interfaces.
The foregoing and other objects, features and advantages of the invention will become more readily apparent from the following detailed description of a preferred embodiment of the invention which proceeds with reference to the accompanying drawings.
REFERENCES:
patent: 4607379 (1986-08-01), Marshall, Jr. et al.
patent: 4887260 (1989-12-01), Carden et al.
patent: 5648972 (1997-07-01), Gharakhanian
patent: 5737364 (1998-04-01), Cohen et al.
patent: 5761463 (1998-06-01), Allen
Cisco Technology Inc.
Dharia Rupal
Marger & Johnson & McCollom, P.C.
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