COM20019I is a member of the family of Embedded ARCNET Controllers from Microchip. The device is a general purpose communications controller for networking microcontrollers and intelligent peripherals in industrial， automotive， and embedded control environments using an ARCNET protocol engine. The flexible microcontroller and media interfaces， eight-page message support， and extended temperature range of the COM20019I make it the only true network controller optimized for use in industrial， embedded， and automotive applications. Using an ARCNET protocol engine is the ideal solution for embedded control applications because it provides a deterministic token-passing protocol， a highly reliable and proven networking scheme， and a data rate of up to 312.5 Kbps when using the COM20019I. A token-passing protocol provides predictable response times because each network event occurs within a predetermined time interval， based upon the number of nodes on the network. The deterministic nature of ARCNET is essential in real time applications. The integration of the 2Kx8 RAM buffer on-chip， the Command Chaining feature， the maximum data rate， and the internal diagnostics make the COM20019I the highest performance embedded communications device available. With only one COM20019I and one microcontroller， a complete communications node may be implemented. For more details on the ARCNET protocol engine and traditional dipulse signaling schemes， refer to the ARCNET Local Area Network Standard， available from Standard Microsystems Corporation or the ARCNET Designer‘s Handbook， available from Datapoint Corporation. For more detailed information on cabling options including RS485， transformer-coupled RS-485 and Fiber Optic interfaces， refer to the following technical note which is available from Standard Microsystems Corporation： Technical Note 7-5 - Cabling Guidelines for the COM20020 ULANC.