computer networking A computer network is a collection of communicating computers and other devices, such as printers and smart phones. In order to communicate, the computers and devices must be connected by wired media like copper cables, optical fibers, or b ...

, a token bus network is a network implementing a

token-passing On a local area network, token passing is a channel access method where a packet called a ''token'' is passed between nodes to authorize that node to communicate. In contrast to polling access methods, there is no pre-defined "master" node. The most ...

protocol over a virtual ring on a

coaxial cable Coaxial cable, or coax (pronounced ), is a type of electrical cable consisting of an inner Electrical conductor, conductor surrounded by a concentric conducting Electromagnetic shielding, shield, with the two separated by a dielectric (Insulat ...

Network

A token is passed around the network nodes and only the node possessing the token may transmit. If a node doesn't have anything to send, the token is passed on to the next node on the virtual ring. Each node must know the address of its neighbour in the ring, so a special protocol is needed to notify the other nodes of connections to, and disconnections from, the ring.

Ethernet Ethernet ( ) is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 198 ...

's access protocol could not absolutely guarantee a maximum time any station would have to wait to access the network, so was thought to be unsuitable for manufacturing automation applications. The Token bus protocol was created to combine the benefits of a physical bus network with the deterministic access protocol of a Token Ring network.

IEEE 802.4

Token Bus was standardized by IEEE standard 802.4. It was mainly used for industrial applications. Token Bus was used by

General Motors General Motors Company (GM) is an American Multinational corporation, multinational Automotive industry, automotive manufacturing company headquartered in Detroit, Michigan, United States. The company is most known for owning and manufacturing f ...

for their

Manufacturing Automation Protocol Manufacturing Automation Protocol (MAP) was a computer network standard released in 1982 for interconnection of devices from multiple manufacturers. It was developed by General Motors to combat the proliferation of incompatible communications stand ...

(MAP) standardization effort. This differs from

Token Ring Token Ring is a Physical layer, physical and data link layer computer networking technology used to build local area networks. It was introduced by IBM in 1984, and standardized in 1989 as IEEE Standards Association, IEEE 802.5. It uses a sp ...

networks in that the endpoints of the bus do not meet to form a physical ring. In order to guarantee the packet delay and transmission in the Token Bus protocol, a modified Token Bus was proposed in manufacturing automation systems and

flexible manufacturing system A flexible manufacturing system (FMS) is a manufacturing system in which there is some amount of flexibility that allows the system to react in case of changes, whether predicted or unpredicted. This flexibility is generally considered to fall ...

(FMS). To optimize deterministic access required by real-time IoT communication in a distributed manufacturing plant or

IIoT The industrial internet of things (IIoT) refers to interconnected sensors, instruments, and other devices networked together with computers' industrial applications, including manufacturing and energy management. This connectivity allows for data ...

, token bus method can also be implemented according to

IEEE 802.15.4 IEEE 802.15.4 is a technical standard that defines the operation of a low-rate wireless personal area network (LR-WPAN). It specifies the physical layer and media access control for LR-WPANs, and is maintained by the IEEE 802.15 working group, ...

. A means for carrying

Internet Protocol The Internet Protocol (IP) is the network layer communications protocol in the Internet protocol suite for relaying datagrams across network boundaries. Its routing function enables internetworking, and essentially establishes the Internet. IP ...

over

IEEE 802 IEEE 802 is a family of Institute of Electrical and Electronics Engineers (IEEE) standards for local area networks (LANs), personal area networks (PANs), and metropolitan area networks (MANs). The IEEE 802 LAN/MAN Standards Committee (LMSC) main ...

networks, including token bus networks, was developed. The IEEE 802.4 Working Group has disbanded and the standard has been withdrawn by the IEEE.

References

{{DEFAULTSORT:Token Bus Network Local area networks IEEE 802 Link protocols

Network

IEEE 802.4

See also

References