Manufacturing Automation Protocol (MAP)
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Manufacturing Automation
Protocol (MAP)
Sviluppato specificatamente per comunicazioni tra computer in un
ambiente di produzione industriale
Nel 1980 General Motors decide di iniziare lo sviluppo di un protocollo di
rete per scambio di dati veloce e senza rumore. Questo schema
intendeva fornire uno standard comune per tutte le apparecchiature al
fine di semplificare la loro integrazione
Nel 1985 GM capì che non poteva realizzare il CIM in questo modo: solo
il 15% di 40.000 dispositivi programmabili potevano comunicare
Nessun fornitore poteva soddisfare tutte le aspettative e più fornitori
causavano incompatibilità al livello delle comunicazioni
Reti e Sistemi per l’Automazione Stefano PanzieriMAP
Problemi:
1. Difficoltà nel convincere I fornitori dei vari paesi ad aderire ad un singolo standard
2. Gli standards sono complessi ed è difficoltoso e costoso sviluppare hardware e
software
3. Vesioni 2.1 e 2.2 lasciavano l’application-layer sotto-definito, solo nella versione 3.0
(1987) fu completamente definito: sorsero ulteriori disaccordi
4. Il protocollo MAP non è chiaramente definito in un unico documento
FullMAP 3.0 (1987)
MiniMap (1988) è una versione contenente solo I livelli 1,2 e 7 (non full OSI
standard) ed è un’architettura ridotta carrier band, single channel più veloce
ed efficiente utilizzato per comunicare con I dispositivi
Una versione del MAP, EPA (Enhanced Performance Architecture) è stata
sviluppata, ed è supportata, dalla industria del controllo di processo (Full
MAP in parallelo al MiniMAP) nel 1988.
Reti e Sistemi per l’Automazione Stefano PanzieriMAP Physical Layer
1. Broadband
1. many simultaneous communications on same wire at same time,
using varied frequencies for transmit channels and receive channels.
2. uses a head end re-modulator to retransmit the signal
3. each station needs MAP hardware
4. for very large factories
5. uses a 1 inch (2.5 cm) thick cable
6. maximum 10 Megabits/sec. per channel
2. Carrierband
1. uses smaller cables
2. less expensive
3. rate of 5 to 10 Megabits second (single channel)
Reti e Sistemi per l’Automazione Stefano PanzieriMAP Data Link Layer
Real time response was required, so token passing is used
If a token passing ring is broken, the computers will wait, and
eventually each half of the broken ring will have tokens being
passed
Extensive algorithms have been developed for control of token
passing, and resolution of conflicts
Preferred Standards
Preferred LAN is IEEE 802.4 token-passing bus.
Uses standard ISO network, transport, session, and presentation layers
CNMA has lobbied for the inclusion of Ethernet (IEEE 802.3) as an
alternative for the standard
Reti e Sistemi per l’Automazione Stefano PanzieriMAP Application Layer 1. FTAM (File Transfer Access Method) for file transfer 2. MMS (Manufacturing Message System) for content of messages bound for robotic equipment 3. ACSE (Association Control for Service Elements) for program to program communication The set of protocols should make communication between heterogeneous devices, not only in moving data around, but also in communication the meaning of that data Reti e Sistemi per l’Automazione Stefano Panzieri
MAP Layers vs. ISO/OSI Reti e Sistemi per l’Automazione Stefano Panzieri
MMS modeling
The dominant aspect of MMS (Manufacturing Message
Specification ISO/IEC 9506 Part I) is the concept of
modeling
MMS defines models that describe the way in which
resources are made available and the way in which these
resources are accessed.
At the center of the MMS modeling concept are:
the Virtual Manufacturing Device (VMD)
abstract object models
Reti e Sistemi per l’Automazione Stefano PanzieriVirtual Manufacturing
Device (VMD)
The VMD describes the externally visible behavior of an MMS
device when it makes resources (i.e., data table memory,
program files) available to other MMS devices
Assume, for example, that an MMS device exists and it makes
system data table memory available to other MMS devices. It is
the VMD that describes the way in which that MMS device makes
the data table memory available
This mapping of a device to the VMD model establishes a device
as a virtual device on the MAP network, allowing it to be
accessed by other virtual devices through the use of MMS
services.
Note that the VMD model theoretically exists within an MMS
device
Reti e Sistemi per l’Automazione Stefano PanzieriThe MMS Abstract Object
Models
MMS also defines a series of abstract object models that describe
the externally visible behavior associated with a particular MMS
service or group of services
The concept of object models is entirely abstract within the MMS
specification, but represents real resources within a system
This results in a standard external view of all MMS devices that
make system resources available, but allows each MMS device to
implement the model in a manner that is appropriate for the system
The models define abstract objects which are part of the VMD
An application program calls on the MMS services associated with
a particular object to perform operations on that object.
Reti e Sistemi per l’Automazione Stefano PanzieriTOP
(Technical and Office Protocol)
TOP (Technical and Office Protocols) is designed for the office
environment.
Lanciato dalla BOEING per il CAD distribuito nel 1985
TOP 3.0 nel 1987
Layers 1 and 2
Preferred LAN is IEEE 802.3 Ethernet, But allows for Token Bus (IEEE
802.4) and Token Ring (IEEE 802.5). Fibre optical media will be added
when they are defined
Layers 3-6
uses same ISO standards for network, transport, session and
presentation layers that MAP uses
Reti e Sistemi per l’Automazione Stefano PanzieriTOP Application Layer ACSE and FTAM are the same as MAP, MMS is not included (MHS) CCITT X.400 message handling service provides electronic mail transfers of all types of documents ISO Virtual terminal protocol to allow a terminal on any machine to log onto any other machine. ODA/ODIF (ISO Office Document Architecture and Office Document Interchange Format) To permit formatted documents to be transmitted independently of the package used to create them. (Text, and Raster or Line graphics) CGM (ISO Computer Graphics Metafile) to permit the exchange of geometrical graphics IGES (ANSI Initial Graphics Exchange Standard) to exchange product design information among CAD/CAM workstations. Reti e Sistemi per l’Automazione Stefano Panzieri
TOP Layers vs. ISO/OSI Reti e Sistemi per l’Automazione Stefano Panzieri
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