M-Modules are a

mezzanine A mezzanine (; or in Italian, a ''mezzanino'') is an intermediate floor in a building which is partly open to the double-height ceilinged floor below, or which does not extend over the whole floorspace of the building, a loft with non-sloped ...

(

computer hardware Computer hardware includes the physical parts of a computer, such as the case, central processing unit (CPU), random access memory (RAM), monitor, mouse, keyboard, computer data storage, graphics card, sound card, speakers and motherboard. ...

) standard mainly used in industrial computers. Being mezzanines, they are always plugged on a carrier

printed circuit board A printed circuit board (PCB; also printed wiring board or PWB) is a medium used in electrical and electronic engineering to connect electronic components to one another in a controlled manner. It takes the form of a laminated sandwich str ...

(PCB) that supports this format. The modules communicate with their carrier over a dedicated bus, and can have all kinds of special functions. M-Modules are standardized as

ANSI The American National Standards Institute (ANSI ) is a private non-profit organization that oversees the development of voluntary consensus standards for products, services, processes, systems, and personnel in the United States. The organi ...

/VITA 12-1996

expansion card In computing, an expansion card (also called an expansion board, adapter card, peripheral card or accessory card) is a printed circuit board that can be inserted into an electrical connector, or expansion slot (also referred to as a bus sl ...

s and are especially suited for adding any kind of real-world I/O to a system in a flexible way. There are modular I/O extensions for all types of industrial computers, from embedded systems up to high-end workstations. The M-Module Interface – a fast

asynchronous Asynchrony is the state of not being in synchronization. Asynchrony or asynchronous may refer to: Electronics and computing * Asynchrony (computer programming), the occurrence of events independent of the main program flow, and ways to deal wit ...

parallel interface – offers sophisticated functions like 32-bit data bus, burst transfers up to 100 MB/s,

DMA DMA may refer to: Arts * DMA (magazine), ''DMA'' (magazine), a defunct dance music magazine * Dallas Museum of Art, an art museum in Texas, US * Danish Music Awards, an award show held in Denmark * BT Digital Music Awards, an annual event in the U ...

and trigger capabilities. M-Modules also offer direct front-panel connection rather than requiring a separate adapter panel with ribbon-cable connections. This provides a clean path for sensitive signals without loss of data or signal quality – using, for example, shielded D-Sub connectors and

coaxial cable Coaxial cable, or coax (pronounced ) is a type of electrical cable consisting of an inner conductor surrounded by a concentric conducting shield, with the two separated by a dielectric ( insulating material); many coaxial cables also have a p ...

Overview

The mezzanine approach to placing multiple functions in a single card slot has been around for a long time both in proprietary and open standard forms. Valid arguments can be put forth for both of these approaches. The M-Module is one open standard that is gaining increasing popularity for applications in the fields of analog and digital I/O, instrumentation, robotics, motion functions and fieldbuses. This standard was originally developed in Germany by MEN Mikro Elektronik for

VMEbus VMEbus (Versa Module Europa or Versa Module Eurocard bus) is a computer bus standard, originally developed for the Motorola 68000 line of CPUs, but later widely used for many applications and standardized by the IEC as ANSI/IEEE 1014-1987. ...

applications and was soon expanded to support the

CompactPCI CompactPCI is a computer bus interconnect for industrial computers, combining a Eurocard-type connector and PCI signaling and protocols. Boards are standardized to 3 U or 6U sizes, and are typically interconnected via a passive backplane. The ...

bus as well. It has been embraced as

/VITA 12-1996. In addition to the single wide form shown, M-Modules can be developed in double, triple and quadruple wide configurations. Because of the standard's genesis in the VME world it is sized such that 4 fit in a 6U module and 2 in a 3U module. Conveniently, because of the way other backplane standards have evolved, 4 units easily fit the front panel space in

VXI VME eXtensions for instrumentation bus (VXI bus) refers to standards for automated test based upon VMEbus. VXI defines additional bus lines for timing and triggering as well as mechanical requirements and standard protocols for configuration, m ...

and 6U

cPCI CompactPCI is a computer bus interconnect for industrial computers, combining a Eurocard-type connector and PCI signaling and protocols. Boards are standardized to 3 U or 6U sizes, and are typically interconnected via a passive backplane. The ...

PXI PCI eXtensions for Instrumentation (PXI) is one of several modular electronic instrumentation platforms in current use. These platforms are used as a basis for building electronic test equipment, automation systems, and modular laboratory instru ...

while 2 will fit in the front panel space of 3U

/PXI and up to 8 will fit in a 1U LXI rack mount carrier. At the present time a number of instruments are available in the M-Module form factor in the following categories: *

Pulse generator A pulse generator is either an electronic circuit ''or'' a piece of electronic test equipment used to generate rectangular pulses. Pulse generators are used primarily for working with digital circuits; related function generators are used pri ...

s *

Function generator In electrical engineering, a function generator is usually a piece of electronic test equipment or software used to generate different types of electrical waveforms over a wide range of frequencies. Some of the most common waveforms produced ...

s *

Arbitrary waveform generator An arbitrary waveform generator (AWG) is a piece of electronic test equipment used to generate electrical waveforms. These waveforms can be either repetitive or single-shot (once only) in which case some kind of triggering source is required (i ...

s *Digital word generators *Digital multi-meters *Counter/Timers *

Rubidium Rubidium is the chemical element with the symbol Rb and atomic number 37. It is a very soft, whitish-grey solid in the alkali metal group, similar to potassium and caesium. Rubidium is the first alkali metal in the group to have a density higher ...

sources *

OCXO A crystal oven is a temperature-controlled chamber used to maintain the quartz crystal in electronic crystal oscillators at a constant temperature, in order to prevent changes in the frequency due to variations in ambient temperature. An oscillat ...

's * GPS timing receivers *

Distribution amplifier In electronics, a distribution amplifier, or simply distribution amp or DA, is a device that accepts a single input signal and provides this same signal to multiple isolated outputs. These devices allow a signal to be distributed to multiple de ...

s *Precision

voltage source A voltage source is a two-terminal device which can maintain a fixed voltage. An ideal voltage source can maintain the fixed voltage independent of the load resistance or the output current. However, a real-world voltage source cannot supply unl ...

s *

MIL-STD-1553 MIL-STD-1553 is a military standard published by the United States Department of Defense that defines the mechanical, electrical, and functional characteristics of a serial data bus. It was originally designed as an avionic data bus for use with ...

CANbus A Controller Area Network (CAN bus) is a robust vehicle bus standard designed to allow microcontrollers and devices to communicate with each other's applications without a host computer. It is a message-based protocol, designed originally for m ...

, ARINC429 *Switching modules * Serial, Analog & Digital I/O A significant advantage to the M-Module is that it has a relatively straight forward set of electrical and mechanical specifications. This enables an engineer to design a function that might be required without having to become an expert on VXI, PXI or LXI as carriers are available to allow the design to be ported to the

backplane A backplane (or "backplane system") is a group of electrical connectors in parallel with each other, so that each pin of each connector is linked to the same relative pin of all the other connectors, forming a computer bus. It is used as a backbo ...

or bus of the test system in use.

Supporting the standard

As with any mezzanine card, a means must be provided through which the card may be adapted to a backplane or higher level interface. Such a device is generally referred to as a carrier. These come in two types: non-intelligent and intelligent. The functions performed by the former include the simpler functions such as mounting and providing power as well as the more complex such as providing translation between bus types, protocols, routing of triggers and interrupts and making each mezzanine appear as a separate instrument to the host backplane. Intelligent carriers will generally perform all of the functions of the non-intelligent plus perform pre or post processing of data, allow the combination of multiple instruments into composite instruments that then may be controlled at a higher level, and perform translation of commands from older instruments so as to facilitate replacement of Legacy instruments. Of equal or greater importance in the support of the mezzanine is the software. The majority of the M-Module instrument types referenced above come with VXI/PXI Plug-and-Play or IVI drivers. However, a number of the more control oriented M-Modules are supported only with C drivers. Actions are underway that are described below which allow application of the

Plug-and-Play In computing, a plug and play (PnP) device or computer bus is one with a specification that facilitates the recognition of a hardware component in a system without the need for physical device configuration or user intervention in resolving resou ...

drivers across multiple platforms.

Benefits of modularity

Perhaps the greatest advantage of an M-Module mezzanine instrument is the ability of both the vendor and the user to become "Platform Agnostic". From the vendor's perspective, it is only necessary to develop one instrument, say a Pulse Generator, and with the use of carriers he can produce the same product into

, VME, LXI and other applications. This greatly reduces development costs when compared to the development of pulse generators for multiple buses.

References

{{Reflist

External links

*August 2008
Evaluation Engineering Magazine
enews article
ANSI Mezzanine Modules Provide Instrument Design/Replacement Flexibility
authored by Dr. Fred Harrison, Gary Guilbeaux, and David Clark of C&H Technologies, Inc. *ANSI/VITA 12-1996, "American National Standard for The Mezzanine Concept M-Module Specification", VMEbus International Trade Association
www.vita.comMezzanines International
M module

Overview

Supporting the standard

Benefits of modularity

See also

References

External links