Bus Standards for Your Network
What is a Computer Network Bus?
When all nodes in a local area network are connected to a main cable called a bus, sometimes misspelled as buss, it creates a bus network. If one node on the bus network fails, the other devices can still talk to each other through the bus. Bus networks are expanded by adding more cable or more nodes.
Bus networks are limited by the speed at which data can be transmitted through the cable; very long cables are less effective, so bus networks rarely include distant sites. VME buses were originally designed for connecting multiple computers into a local area network, but they are also used in industrial controls to manage motor control centers and the computers that control production lines. VME buses are also used in telecommunications.
Vendor Bus Standards
Bus networks need to handle hardware and cables from many different manufacturers.
ARM Microcontroller Bus Architecture or AMBA is used for on-chip communication bus. AMBA contains three distinct standards.
Advanced high performance bus or AHB bus architecture is used for high frequency chips that use a lot of bandwidth like microprocessors. Advanced system bus is used for high frequency components that do not require advanced protocols like microprocessors. Advanced peripheral bus or APB is used for low bandwidth and low frequency communications such as keyboards and timers. APB buses generally connect to an AHB bus.
IBM CoreConnect has three types of buses. The processor local bus or PLB is high speed and has a high frequency. The on-chip peripheral bus or OPB connects to peripheral components like mice and keyboards. The device control register bus or DCR bus accesses the control registers of PLB and OPB buses.
STMicroelectronics STBus standard applies to on-chip interconnection. The standard was developed for devices like ATM networks and set top boxes connected to televisions. The STMicroelectronics STBus standard has three bus protocols.
Type 1 is the simplest bus protocol, Type 3 is the most advanced and contains transaction labeling, while Type 2 supports SPLIT transactions.
IEEE Bus Standards
The VMEbus extensions for instrumentation or VXI standard was derived from the VME standard. The VXIbus, the VXI bus standard, became IEEE 1155. The VXI bus standard does not cover instrument on a chip or IAC systems, and users who only need a few channels of data can use a PC plug-in instead if they do not need millions of data samples analyzed each second.
The VME bus standard was adopted as IEEE standard 1014 in 1987. The VME bus standard for 64 bit microprocessors is called VME64. VME64 was incorporated into the IEEE standard in 1994. IEEE 488 is the standard for automated test equipment.
Eventually, the need for universal bus standards led to the VMEbus International Trade Association or VITA standards, which were later adopted by ANSI. For example, ANSI/VITA 6 is for the SCbus standard for the VME platform. It was originally approved in 1994. VITA 42.1 is the VITA standard for the VME Switched Serial or VXS specification.
VXS is designed to be backward compatible with VME64x circuit boards while being capable of handling high speed connections. VITA 46 is the VME Advanced Module Format standard. This platform supports VME bus signals and serial fabric signals. VITA XMC specifications are in VITA standard 42.0.
Industry Association Bus Standards
The company Dialogic created the PCM Expansion bus standard. This standard included Dialogic hardware as well as other supplier's hardware. The Multivendor Integration Protocol or MVIP-90 was developed by a group of seven different vendors in an effort to build hardware that worked with each other's products.
The Virtual Sockets Interface Alliance or VSIA created an on-chip bus virtual component interface. The VMEbus International Trade Association or VITA bus standards were created by the industry association but have been adopted widely since they were picked up by ANSI International.