The VME bus Architecture

What is VME bus?

VMEbus is short for VersaModular Eurocard bus, and thus from the name, is a bus system (or a computer path system) for industrial applications such as VME power supplies, embedded single board computers (SBC), actuators automation, etc. It was originally developed by Motorola technical employees in Germany (yr. 1980) and soon after, also adopted by Signetics, Philips, Thomson, and Mostek.

After its standardization by the International Electrotechnical Commission (IEC) and American National Standards Institute (ANSI), many different versions of the VME bus Architecture were launched, having a higher capacity than the original 16-bit bus, such as the VME64 (yr. 1994), VME64x (yr. 1997), VME320 (yr. 1997), and other VME32/64 boards.

Motorola's continuation of the VMEbus project became its Motorola Single Board Computers (SBC) line of production, dubbed Motorola VME (MVME).

VME bus Specification & architecture

VME bus operates in DC voltages of 5.2V, +12V and -12V with three main signal lines, which are ACFAIL, PG (Power Good) and SYSRESET. It is widely available as 16bit, 32bit and 64bit VME computer systems. A VME system is a set of connected VME boards, plugged to a VME backplane or VME chassis

With multi-processing capabilities, allowing up to 21 processors, VMEbus is a non-proprietary bus standard that makes forward and backward compatibility an easy task.

Due to its effectiveness and sheer speed, it is widely used throughout many mission critical systems and industries, such as:

• Nuclear and Medical industries in nuclear medical systems.
• Semiconductor and Industrial Automation industries in semiconductor robots
• Telecommunications and Transportation industries in Federal Aviation Administration operations.
• The U.S. Military in satcom military systems.

View U.S.Technologies' vast inventory of VME products

In simple terms, the VME bus provides a way for different proprietary systems to communicate between each other. So if a System A has a VME compatibility, then a VME bus can be used to allow communication to a System B, so long as System B can also be plugged into a VME bus.

VME Board Dimensions / VME Card Dimensions

There are three basic VMEbus card sizes (L x H):

1. 3U Size A 160mm x 100mm
2. 6U Size B 160mm x 233mm or
         Size C 340mm x 233mm
3. 9U Size D 340mm x 360mm

Typical card guides accept VME card widths of 1.6 +/- 0.2 mm. Other widths may not fit correctly.