Buying a VME Bus

How to find manufacturers of the VersaModule Eurocard bus
By Kenneth Benson, Freelance Writer Self-Employed A VersaModule Eurocard (VME) bus is a 32-bit computer bus developed by Motorola, Signetics, Mostek and Thompson CSF and includes VME adapters, VME controllers, VME extenders, VME interfaces, VME processors and VME switches. It is defined by the IEEE (Institute of Electrical and Electronics Engineers) standard 1014-1987. 
 

VME buses have many uses including traffic control, weapons control, telecommunication switching, data acquisition, video imaging and robotics. They can withstand shock, vibration and extended temperatures better than the buses used in desktop computers, making them ideal for harsh environments.

Based on the VME IEEE standards set forth in 1987, a VME bus system includes:

1. VME bus mechanical specifications such as board
    dimensions, connector specifications and enclosure
    characteristics.

2. VME bus electronic specifications for sub-bus structures, signal
     functions, timing, signal voltage levels and master/slave
     configurations.

A VME bus interface system has four sub-buses:

1. The arbitration VME bus controls requests from various
     devices using an arbiter module, giving permission to each
     device to use the bus and notifying requesting devices when
     the bus is busy.

2. The data transfer VME bus is used for reading and writing
     operations between modules.
 
3. The priority interrupt VME bus handles interrupts and monitors
     the interrupt request lines.

4. The utility VME bus supports a system clock.

VME bus interfaces come in three sizes:

1. VME bus size 3U, which is 4 x 6 inches
2. VME bus size 6U, which is 6 x 12 inches
3. VME bus size 9U, which is 14 x 18 inches

Where to locate more information about VersaModule Eurocard bus

VME bus information is available in detail at many websites.
Try: WhatIs.com explains VME bus technical information and provides other data on the entire VME bus interface system. interfacebus.com, provides a lengthy description of VME bus systems and offers many detailed diagrams. Webopedia offers a brief definition of the VME bus system.

Find information on VME bus manufacturers

There are more than 300 VME bus manufacturers worldwide. Some of the larger companies are listed below.
Try: National Semiconductor Corp. manufacturers the 54/74ETL16245, 16 bit transceiver Incident Wave Switching IC VME bus. Texas Instruments produces 74VMEH22501, VME bus 8 bit transceiver/2eSST and ABTE16245 ICs. Tundra Semiconductor makes VME64 Bus Controller ICs, VME Bridges to PCI/Local VME Bus interfaces, and PCI-X to 2eSST VME bus bridge chip TSI148 "Tempe." Motorola was the first manufacturer of VME bus interfaces including: VME adapters, VME controllers, VME extenders, VME interfaces, VME processors and VME switches.

Find information on organizations and associations associated with the VME bus

To find out about VME bus usage, try these organizations, which provide a forum for VME bus manufacturers and VME bus users.
Try: VITA is perhaps one of the largest associations in the world associated with VME busses, their uses, and standards associated with VME controllers. They also contain a listing of reputable vendors. VME International Physics Association is another association that monitors the use of VME busses, making sure they are in accordance with IEEE standards.

Locate vendors to buy a VME bus board and VME bus components

You can purchase VME interface systems and VME controllers from many different vendors.
Try: Schroff is a worldwide supplier of many VME bus interfaces and related devices. Carlo Gavazzi Computing Solutions offers a wide range of VME bus interfaces and other parts including VME adapters, VME controllers, VME extenders, VME processors and VME switches. SHF Communication Technologies sells many VME bus interface related parts.

• When replacing a VME bus or any VME interface parts, make sure you really need to replace them. When in doubt , check with vendors, manufacturers or other technical sources.
• VME bus interfaces are heavily regulated by the government based on IEEE regulations and standards. Check these standards for proper VME bus usages.