Abstract: Improved modular transient voltage surge suppressor apparatus are disclosed that equalize transient current sharing between multiple modules. In general, such apparatus includes first and second transient voltage surge suppression modules, each module having a non-conductive housing with a surge suppression circuit contained therein, and first and second electrically-conductive buses mechanically coupled to the non-conductive housing and electrically coupled to first and second terminals of the surge suppression circuit, respectively. A first bus coupler couples the first electrically-conductive buses of the first and second transient voltage surge suppression modules and a second bus coupler couples the second electrically-conductive buses of the first and second transient voltage surge suppression modules, whereby the surge suppression circuits in each of the first and second modules are electrically coupled in parallel.

Abstract: A chassis for fiber optics communication equipment, having a housing with first and second opposing sides, and a back panel cooperating with the housing to provide fore-and-aft slots for cassettes containing optical communication equipment. A remote user interface module for making connections to other items of equipment, and a local user interface module for display of conditions in the cassettes, are situated at opposite sides of the housing, and are both connected to the base by docking stations which allow these modules to be interchanged in position so that either of the first or second sides of the housing may become the front of the chassis; i.e. may be adjacent the local user interface module. This allows the chassis to be reversible so that the cassettes can be removed either from the front or from the rear of the chassis while the local user interface module remains at the front of the chassis.

Abstract: A module connection assembly connects modules in a torus configuration that can be changed remotely. In particular, a single module can be added to or deleted from the configuration by remotely switching from conducting paths that provide end-around electrical paths to conducting paths that provide pass-through electrical paths. The assembly includes two backplanes, a first set of module connectors for electrically connecting modules to one of the backplanes, and a second set of module connectors for electrically connecting modules to the other backplane. The assembly further includes configuration controllers. Each configuration controller selects between end-around electrical paths that electrically connect multiple module connectors of the first set to each other, and pass-through electrical paths that electrically connect module connectors of the first set to module connectors of the second set.

Abstract: A control device (10) for electro-hydraulic support frames with a casing (11) accommodating a circuit, several plug-in connectors (20) accessible from outside the casing (11) for the connection of control leads, and with actuating control elements (13) connected to the circuit. The control elements (14, 15, 16, 17, 18) are grouped together in several exchangeable modules (27), accommodated in the casing (11), which are connected to the circuit and to each other by plug-in connecting elements (30) when installed in the casing (11). The modules (27) are exchangeable independently of each other. The operating keys of a keyboard (16) and/or an indicator unit (18) can be combined in one operating module (28), which can be removed from the casing (11). The actual control of the control device in the casing (11) and operation of the support frame is permitted to continue during the exchange of the operating module (28).

Abstract: A container case for a card type memory comprises a storage space having an inserting entrance for inserting the card type memory, a resilient engaging pawl provided inside of the storage space for engaging with the card type memory, a leaf spring for ejecting the card type memory out of the storage space by resilient power, and a rotation supporting projection provided inside of the storage space for rotating the card type memory at said rotation supporting projection in the storage space to be easily ejected from the storage space with a comfortable mechanical feeling.

Abstract: A method of manufacturing a small, thin card-type storage device is capable of easily manufacturing a frame for the storage device from a variety of resin materials without molding a very thin recessed bottom of the supporter. The method prepares a card-type support frame member from resin and a sheet material, cuts the sheet material into the size of the support frame member, to form a support sheet, bonds the support sheet to a bottom surface of the support frame member, to form a frame, and fits a memory module to be fixed in an opening of the support frame member in the frame, thereby completing the card-type storage device.

Abstract: A modular multinode computing apparatus includes a rack mountable enclosure and more than one system board that is secured within the enclosure in a high density configuration that is preferably configured so that the system boards are positioned in substantially the same plane, which is also the plane in which the apparatus resides when mounted within a rack. The enclosure preferably has four system boards, and is sized as a 1 u form factor. When mounted in a rack with like units, the apparatus permits a data center or computing cluster to be fabricated that has a processing density that is much greater than conventional clusters that are configured with 1 u based single node units.

Abstract: A wiring board according to the present invention includes a mounting region in which memories having different storage capacities can be mounted. The mounting region has: first wires for, when a first memory is mounted, making it possible to access all the addresses of the first memory; and second wires for, when a second memory having a storage capacity different from that of the first memory, making it possible to access to all the addresses of the second memory. For this reason, before an electronic device on which the wiring board is mounted is shipped, a memory mounted in the mounting region can be selected depending on the demand of a user.

Abstract: A system and method for identifying a match between an industrial PC to a slot in a rack which uses a blind mating keying and locking plates, so that when the mechanical keying plate and locking plate do match, then full insertion of the PC into the slot is permitted. When a mis-match occurs, then full insertion is prohibited.

Abstract: A modular computer system mechanical interconnection includes a primary chassis having a first opening and a secondary chassis attached to the primary chassis and having a second opening, wherein the first opening and the second opening are generally aligned. The apparatus further includes a backplate covering the aligned first opening and second opening.

Abstract: A cost effective and easily manufactured filler for a removable system component. A hard disk drive filler embodiment is disclosed having five exterior sides and internal baffles to simulate the airflow modifying characteristics of a hard disk drive. The hard disk drive filler is stackable, flame-resistant, and is manufactured by an injection-molding process.

Abstract: A scalable electronic system is disclosed, comprised of multiple modular electronics clusters. Each modular electronics cluster comprises a receptacle for routing signals, and multiple resource cartridges for performing electronic functions. The resource cartridges are capable of being aligned in close proximity to the receptacle for communicating signals to and from the receptacle. In addition, the resource cartridges aligned with the receptacle are also capable of communicating with each other. The resource cartridges can be aligned or removed from alignment with the receptacle, without the need for additional electrical connection hardware. The receptacle includes at least one vertical transport channel for communicating with other modular electronics clusters.

Abstract: A Universal Serial Bus docking station is provided in which a USB hub includes a housing which may receive at least one additional USB module which is connected to the USB hub without the use of an additional cable. In a preferred embodiment of the invention, up to three USB modules may be inserted into the housing in stacked arrangement. In addition, each USB module maybe used as a stand alone unit by snapping a sleeve onto the rear of the module. Still further, a USB connector is adapted for use standing vertically from a circuit board and being retained by spring clips extending through the circuit board in a direction substantially parallel to the longitudinal axis of the connector.

Abstract: A method of manufacturing a small, thin card-type storage device is capable of easily manufacturing a frame for the storage device from a variety of resin materials without molding a very thin recessed bottom of the supporter. The method prepares a card-type support frame member from resin and a sheet material, cuts the sheet material into the size of the support frame member, to form a support sheet, bonds the support sheet to a bottom surface of the support frame member, to form a frame, and fits a memory module to be fixed in an opening of the support frame member in the frame, thereby completing the card-type storage device.

Abstract: Electronics devices having a housing with ergonomic features that enhance the ability of a user to hold the electronics devices for extended periods of time using different grips. The housing has a middle gripping region that is narrower than a top section and a bottom section positioned to either side of the gripping region. A keypad structure is positioned at the middle gripping section on a front surface of the housing. The back surface of the housing has a depression positioned generally at the midline of the housing. The depression engages the fingertips, the palm, or other portions of the hand when the user holds the electronics device. Rounded corners where the lateral surface of the housing meet the front surface and the back surface contribute to the user's comfort when holding the electronics device.

Abstract: A system of interlocking modules for use with a programmable logic controller. The system utilizes a plurality of modules, e.g. input/output modules, that are mechanically and electrically interlinked. Modules are electrically connected to adjacent modules by plug portions The mechanical interlocking features and the plug portions are designed to permit insertion and removal of individual modules disposed between adjacent modules, without moving either of the adjacent modules. Also, the plug portions are designed to isolate the electrical connections from vibration.

Abstract: An electrically isolated, combined power and signal coupler, for a patient connected device, is disclosed. A docking station and a portable device, capable of docking with the docking station each include a power coupler and an electrically isolated data transducer. The respective power couplers include a magnetically permeable element including a central pole and a peripheral pole and a printed circuit board with an opening through which the central pole protrudes. The printed circuit board includes windings surrounding the central pole opening: a primary winding in the docking station and a secondary winding in the portable device. When the portable device is docked with the docking station, the magnetically permeable element in the portable device and the magnetically permeable element in the docking station are arranged to form a magnetic circuit, and the data transducer in the portable device and the data transducer in the docking station are arranged to exchange data.

Abstract: This scanner head includes a case member (300b) having a first side wall (300f) and a second side wall (300y), an electric circuit board (105) placed inside the case member (300b), a terminal board (309) including a terminal to be connected to the main apparatus and placed outside the first side wall (300f), a wiring unit (305) for connecting the electric circuit board (105) and the terminal board (309) through a slit opening (300c) formed in the first side wall (300f), and a shield plate (102). This shield plate (102) couples the first side wall (300f) and the second side wall (300y).

Abstract: A portable computer having a main computer body and a keyboard unit slidably attached to the main computer body and movable to various positions in front of the main computer body. A display unit is also slidably attached to the main computer body and movable to various positions up and away from the computer main body.

Abstract: A mounting apparatus for mounting a data storage device in a computer housing includes a bracket, a securing means and a flexible plate. The bracket has a first face for supporting a data storage device, a second face opposite the first face and locking holes in its front portion. The securing means is mounted to a bottom of the data storage device and is moveable with the data storage device to be slid into the corresponding locking hole of the bracket. The flexible plate has a rear end securely fixed to the second face and a front end that has an operating portion extending out of the housing for being operable to move the front end away from the front portion of the bracket. The flexible plate further defines through holes for engaging with the locking holes to releasably block the sliding movement of the data storage device.

Abstract: A structure wherein a hand held computer module can be conveniently and interchangeably coupled to accessory devices. The hand held computer module is detachably connected to a first accessory module by a first interlocking structure. The computer module includes the first interlock mechanism and the first accessory module includes the second interlock mechanism. The first and second interlock mechanisms are mated together to form a physical connection between the computer module and the first accessory module. The first accessory module also includes a third interlock mechanism which is similar to the first interlock mechanism. A second accessory module has a fourth interlock mechanism which is similar to the second interlock mechanism. The first accessory module can be detachably connected to a second accessory module by means of a second interlocking structure which includes the third and fourth interlock mechanisms.

Abstract: Methods of removing and replacing data processing circuitry are provided comprising removing a network interface module from the computer without powering down the computer and removing an interface card from the network interface module. The further acts of replacing the interface card into the network interface module and replacing the network interface module into the computer without powering down the network computer are also performed in accordance with this method.

Abstract: An interface panel for providing telecommunication signals to a plurality of electronic modules housed within an electronics cabinet is provided. A bracket member includes a plurality of openings. A plurality of connectors for receiving a plurality of input cables is positioned within the plurality of openings and is mounted to the bracket. Each of the plurality of connectors includes at least fifteen conductive pins. A plurality of output cables operatively coupled to each of the plurality of connectors is also provided. Each of the plurality of output cables is operatively coupled to a predetermined set of the at least fifteen conductive pins. Each of the plurality of output cables includes an adapter for connection to one of the plurality of electronic modules.

Abstract: A modular surge suppression system for a traffic cabinet. The system comprising a surge suppression module and a modular adapter connected to the circuitry in the traffic cabinet. The modular adapter being configured to connect with the surge suppression module.

Abstract: A vertically mountable semiconductor device including at least one bond pad disposed on an edge thereof. The bond pad includes a conductive bump disposed thereon. The semiconductor device may also include a protective overcoat layer. The present invention also includes a method of fabricating the semiconductor device, including forming disconnected notches in a semiconductor wafer, redirecting circuit traces into each of the notches, and singulating the wafer along the notches to form bond pads on the edges of the resultant semiconductor devices. A method of attaching the semiconductor device to a carrier substrate includes orienting the semiconductor device such that the bond pad is aligned with a corresponding terminal of the carrier substrate, and establishing an electrical connection between the bond pad and the terminal.

Abstract: A protective relay having internal processing circuitry embodied by removable and replaceable modules. Each module includes a main circuit board having common circuitry and also includes removable and replaceable submodules which electrically connect with the main circuit board to perform specific functions. The protective relay can have its functions altered by replacing one or more modules or submodules.

Abstract: An apparatus, computer system and method allow either redundant power supplies or a non-redundant power supply to be mounted in a computer chassis, efficiently fitting into the same space. The apparatus and computer system include a chassis with a power supply bay for holding one of a power supply of a first type and a plurality of power supplies of a second type wherein the power supply bay is capable of receiving either one of the power supply of the first type and the plurality of power supplies of the second type, the power supply of the first type fitting into the same space as the plurality of power supplies of the second type.

Abstract: A vehicle computer system has a housing sized to be mounted in a vehicle dashboard or other appropriate location. A computer is mounted within the housing and executes an open platform, multi-tasking operating system. The computer runs multiple applications on the operating system, including both vehicle-related applications (e.g., vehicle security application, vehicle diagnostics application, communications application, etc.) and non-vehicle-related applications (e.g., entertainment application, word processing, etc.). The computer system has an Internet wireless link to provide access to the Internet. One or more of the applications may utilize the link to access content on the Internet.

Abstract: A vehicle computer system has a housing sized to be mounted in a vehicle dashboard or other appropriate location. A computer is mounted within the housing and executes an open platform, multi-tasking operating system. The computer runs multiple applications on the operating system, including both vehicle-related applications (e.g., vehicle security application, vehicle diagnostics application, communications application, etc.) and non-vehicle-related applications (e.g., entertainment application, word processing, etc.). The applications may be supplied by the vehicle manufacturer and/or by the vehicle user.

Abstract: A system of interlocking modules for use with a programmable logic controller. The system utilizes a plurality of modules, e.g. input/output modules, that are mechanically interlinked to obviate the need for a rack or back plane. Each module includes a movable plug portion that selectively may be moved into engagement with a corresponding plug receptacle of the next adjacent module. The mechanical interlocking features and the plug portions are designed to permit insertion and removal of individual modules disposed between adjacent modules, without moving either of the adjacent modules.

Abstract: Computer-based industrial control systems and methods employing object oriented hardware elements. An object oriented hardware element may comprise a processor core coupled one side to a universal real-world interface circuit, and on the other side to an open bus interface. In a preferred embodiment, the open bus interface provides downloading software programming objects to the microprocessor core. A computer-based control system in accordance with the present invention may comprise a personal computer or central processing unit coupled to a communications network, at least one zone interface module coupled to the communications network and to an open bus, at least one zone device module coupled to the open bus and, if required, one or more zone processor modules coupled to the open bus. Software object may be downloaded from the personal computer or central processing unit to the various modules to achieve modular, exception-based, distributively intelligent (MEDI) I/O control within the system.

Abstract: A structure wherein a hand held computer module can be conveniently and interchangeably coupled to accessory devices. The hand held computer module is detachably connected to a first accessory module by a first interlocking structure. The computer module includes the first interlock mechanism and the first accessory module includes the second interlock mechanism. The first and second interlock mechanisms are mated together to form a physical connection between the computer module and the first accessory module. The first accessory module also includes a third interlock mechanism which is similar to the first interlock mechanism. A second accessory module has a fourth interlock mechanism which is similar to the second interlock mechanism. The first accessory module can be detachably connected to a second accessory module by means of a second interlocking structure which includes the third and fourth interlock mechanisms.

Abstract: A multi-configuration modular computer that can be configured to be different types of personal computers or associated computer devices is disclosed. The multi-configuration modular computer comprises a display module, a keyboard and pointer device module, a motherboard and power module, and an expansion module. By selecting and combining different modules, the multi-configuration modular computer can be configured to be a LCD display monitor, a pen-based computer, a terminal, a network personal computer, a sub-notebook computer, a notebook computer or a desktop computer.

Abstract: A unique cabinet mounted I/O assembly adapted for integration into a control system which allows a block I/O assembly to be mounted in both sides of the cabinet allowing a blind fit of power and signal connections insuring that power will be provided to the block I/O assembly before any application of signals thereto. and preventing any mismatching of I/O units to wrong processor blocks in the cabinet by a color matching scheme.

Abstract: A cabinet having a plurality of compartments adapted to have disposed in a corresponding one thereof one of a plurality of processing unit modules. Each one of the modules includes a case. The case has a motherboard mounting surface adapted to have mounted thereto one of a plurality of differently configured motherboards, each one of the differently configured motherboards having a different arrangement of a CPU, main memory and I/O adapted cards. The case also has a bulkhead mounting surface adapted to have mounted thereto one of a plurality of differently configured I/O bulkheads, each one of the differently configured bulkheads being configured for a corresponding one of the differently configured motherboards. The case has a fan mounting surface adapted to have mounted thereto one of a plurality of differently configured fan assemblies, each one of the differently configured fan assemblies being configured for a corresponding one of the differently configured motherboards.

Abstract: A computer has a mounting arrangement for enabling the same general internal space of the computer to be used either as a drive bay or as an expansion card slot. In one embodiment, the drive unit is mountable on the mounting arrangement by means of a mounting tray. In this case, the tray is preferably formed such that is serves as a blanking plate for blanking the access aperture provided in a housing wall of the computer for accessing external connectors of an expansion card when the latter is mounted in the mounting arrangement. The same fixing element used for securing the expansion card to the housing wall can also be used to secure the mounting tray to that wall.

Abstract: A customizable hand-held data terminal system employs multiple housing bases able to accommodate different components allow the manufacture of hand-held data terminals with a variety of features based on a single design. Because the system according to the present invention does not require the external mounting of components, the ergonomics and basic footprint of the unit remains unaltered. The present system also alleviates problems with moisture resistance, shielding, and survivability under harsh treatment associated with terminals employing externally mounted end cap modules or pod. The present invention employs a plurality of different sized base units which can accommodate a variety of different components and configurations, and wherein the different base units are interchangeable with a single upper surface and user interface comprising a display screen and keypad.

Abstract: An electrical interconnection system for electronic modules that are mountable on a support and stackable against other similar modules where the interconnection system allows for pivotable attachment of the modules to the support and electrical contacting with adjacent modules, such that power and data transmissions can occur therebetween, through an interconnection that protects the contacts during pivoting attachment of the module to the support and assures a reliable and easily established interconnection therebetween.

Abstract: The present invention provides a locking device having a simplified and energy saving configuration that assures to prevent an unintentional erroneous removal of a container case in operation mode from an apparatus main body. The locking device comprises: first engagement device which is an engagement hole 10 provided in an electronic apparatus main body 1; and second engagement device provided in a disc container case 2 that is inserted into and removed from the electronic apparatus through an opening 1a of the electronic apparatus main body 1. The second engagement device includes a movable engagement piece 21 constituted to be movable toward the engagement hole 10 and a movement urging mechanism 23 for urging this movable engagement piece 21. This movement urging mechanism 23 consists of a working member 23A made from a shape-memory alloy that change its distance from a first end to a second end when subjected to a heat; and a fixed base 24 for fixing the second end of the working member 23A.

Abstract: The present invention discloses a power semiconductor module 10 having encapsulated submodules 1 which, for example, is suitable for power switches, rectifiers for the like in industrial or traction drives. The submodules 1 have a sandwiched structure made up of a ceramic substrate, one or a few power semiconductor chips and a molybdenum wafer, and are potted in plastic. They are held in plug-in locations 19 on a common baseplate 11 and make contact via a stack arrangement of conductors 12, 14, 18. Retention and contact of the submodules 1 take place reversibly via pressure contacts 15, 16, 20, clamp contacts 21 or the like. Important advantages of the power semiconductor module 10 relate to the simple and easily scaleable structure, improved ability to withstand thermal load cycles, and the robustness and easy interchangeability of the submodules.

Abstract: A free-space intra-shelf interconnect system is provided in which each of a number of circuit boards in a shelf communicates with any other board through free-space interconnects. Each board is equipped with a free-space transmit coupler to transmit a signal to a free-space receive coupler of an adjacent board. Simply sliding the boards in the shelf and latching them in place as usual, automatically aligns the transmit and receive couplers for optimum coupling. System configurations are provided for building a closed communication loop within the shelf, that allows for data communications between any board within the shelf. Logical addressing allows for interchangeability of boards within a shelf. This, in turn, allows for moving a defective board to the end positions of a shelf for debugging purposes. An extender board for testing and debugging purposes is also provided if free physical access to both board surface areas is simultaneously needed.

Abstract: A method and apparatus for supplying power to a central processing unit (CPU) in computer systems which normally mount CPUs on a motherboard and supplies power to the CPUs via motherboard circuitry which delivers CPU current from power supply sources connected to the motherboard. The method provides the supply of partial or complete power to a CPU mounted on a computer motherboard directly from a power supply and involves the steps (a) disconnecting the power supply to the motherboard; (b) disconnecting the CPU from a CPU socket or plug on the motherboard; (c) mounting the CPU on an adaptor that can be installed in the CPU socket or plug on the motherboard; (d) installing the adaptor and the mounted CPU in the CPU socket or plug on the motherboard; (e) attaching the power supply to the adaptor to provide partial or complete power to the CPU; and, (f) attaching the power supply to the motherboard.

Abstract: A modular electric arrangement for central power supply and control of valves in a valve block including at least one base module having a housing with tow opposed open ends, at least one connection module, and at least one termination module; the base, connection and termination modules having an identical cross-sectional configuration and being releasably connected in-line; the base module accommodating a circuit board and having a side wall with at least one opening therein for access to a connector on the circuit board; the connection module providing a central electric power supply for other modules in the arrangement; and the termination module closing an open end of an adjacent module in the arrangement.

Abstract: A static memory device has compatibility with a disk drive installed in an electronic apparatus as an external storage unit. The static memory device has a first memory board arranged on the same base portion as the one on which the disk drive can be installed, the first memory board having the same projected area as the disk drive. On the first memory board is arranged a storage unit which is accessible at high speed, such as a semiconductor memory. When the storage capacity of the first memory board only is not enough, an extension memory board can be mounted on the first memory board. When the storage capacity is not sufficient even by mounting the extension memory board on the first memory board, a second memory board can be mounted on the extension memory board. Extension memory boards can also be mounted on the second memory board. Even in this state, the shape is the same as that of the disk drive.

Abstract: A module for use with the circuit breaker, the module being arranged to be mounted on an end of the circuit breaker and to monitor and/or control the circuit breaker and/or an electrical circuit control thereby in use. The module can be active or passive, and, where circuit breakers are ganged in side-by-side relationship, the module can be equal in width to the width of the gang breaker unit to which the module is mounted. The invention also resides in the combination of a module and a circuit breaker.

Abstract: An expansion module for connecting additional communication ports (64) to a hub (10) of a communications network, an enclosure containing additional communication ports (64) on a motherboard (43), a hub receiving portion on an exterior of the enclosure, the hub receiving portion being adapted for mounting to a hub (10) of a communications network, a hub receiving opening (37) in the enclosure, a mating interconnection board (121) connected to the motherboard (43) and facing the hub receiving opening (37), the mating interconnection board (121) being adapted for electrical connection with a card edge connector (45) on the hub (10).

Abstract: To provide an electronic equipment mounting device having flexibility in the mounting direction, the device is provided with a mounting jig on which a plurality of tongues are formed and a housing whose flat faces having different areas have slits in them, the tongues being inserted into the slits in a detachable manner. The mounting jig is mounted on, for example, the surface of a wall, and then the housing is coupled to the mounting jig by selectively using one of its side faces.

Abstract: An input/output module functioning as a peripheral channel adapter or gateway to a network in a high speed digital processing system, the input/output module including a plurality of circuit board assemblies and an enclosure for enclosing the circuit board assemblies, the enclosure including a frame having side panels which are hinged to the frame on opposite sides thereof and movable between closed and open positions for providing access to the circuit board assemblies, a plurality of the input/output modules are enclosed within a housing made of metal, that provides EMI shielding for the input/output modules, the enclosures for the plurality of input/output modules defining metal bulkheads within the housing, and a blower located within the housing forwardly of the input/output modules for circulating cooling air through the input/output modules, the input/output modules being configured so that the volume of cooling air supplied to the application specific assemblies is greater than the volume of cooling a

Abstract: A semiconductor device unit includes a holder having a plurality of holding parts, and a plurality of semiconductor devices held by the holding parts of the holder. Each of the semiconductor devices has a generally parallelepiped shape with top and bottom surfaces and at least one side surface provided with leads which are exposed whereby the semiconductor device unit stands by itself on the leads.

Abstract: Modular, portable data collection terminals are disclosed for use in mixed wireless and hard-wired RF communication networks, wherein various radio transmitter modules and associated antennas may be selectively added to a base terminal unit to solve networking problems associated with specific types of business environments. Modularity exists in both the hardware (splitting data collection and processing control circuitry from radio transceiver control circuitry) and software (splitting transceiver-specific, lower level communication protocol from generic, higher level communication protocol). The control circuitry, including associated microprocessors devices, interact to selectively activate communication circuits to perform necessary communication or data processing functions and enter and remain in a power-saving dormant state during other times. To support such dormant or "sleeping" states, a series of communication protocols provide for channel access to the communication network.