Microchip Technology

When configuring a network, the maximum number of nodes and the maximum cable length are limited by the electric capacity of the transceiver. In this case, the network is expanded by a piece of equipment called a "HUB" or "repeater". It may be necessary to have a converter between coax, T/P and the fiber cable. It is easy to design a HUB or repeater because the TMC2005 has various features for expanding such a network.It can connect with HYC9088, RS485 transceiver, HYC5000/4000/2000 and TTL interface for optical module. It can connect with three different transceivers at the same time and convert the media of each. (The data rate cannot be converted. It is necessary to operate all nodes in the same network at the same data rate.) The Hubs can be expanded by connecting two or more TMC2005 chips. By setting one of 5 ports to open-drain output, the Hub can be expanded to either 12 or 16 ports.

The TMC2074 network controller is CircLink technology's flagship product. The TMC2074's flexibility and rich feature set enable a high-reliability and high-performance, real-time and control-oriented network without the cumbersome middle layer protocol stacks and complex packet prioritization schemes typically required. TMC2074 operates at network data transfer rates up to 5 Mbps. Its embedded 1 kByte RAM can be configured into a maximum of 32 pages to implement a 31-node network where each node in the network has the same local memory. The TMC2074 has two operational modes: "Peripheral Mode" and "Standalone Mode". It can operate with or without the existence of a system CPU on a network node. In Peripheral Mode, the TMC2074 has two selectable communication modes, "Free Format Mode" and "Remote Buffer Mode". Free Format mode, retained from ARCNET, is "packet oriented" communication. Remote Buffer mode communication is a CircLink-specific feature, and is a token oriented communication, which includes automatic data transmission when the token arrives. The TMC2074 has a flexible 8-bit or 16-bit databus to interface various CPU types including X86, 68XX, and SHX with multiplexed or non-multiplexed address/data. When operating in Peripheral mode, the TMC2074 has 8-bit programmable I/O available. When operating in Standalone mode, the TMC2074's I/O configuration is16-bit. The TMC2074 also integrates a 3-port hub (two ports for external connection) to accommodate various network topologies (Bus, Star, etc.) and combinations.