Siemens SPC3 Specifications download pdf (Page 3)

Introduction To ProfiBus DP

___________________________________________________________________

_______________________________________________________________________________________

Acromag, Inc. Tel:248-624-1541 Fax:248-624-9234 Email:sales@acromag.com http://www.acromag.com

The following information describes the operation of ProfiBus DP as it

relates to Acromag Series 900PB DP slave I/O modules. For more detailed

information on ProfiBus, you may refer to the ProfiBus Trade Organization at

the PTO website www.profibus.com.

Acromag manufactures a line of I/O modules that support Profibus DP

over RS485. Feel free to visit our website at www.acromag.com to obtain

the latest information about these and other Acromag products.

Acromag Series 900PB modules utilize the popular ProfiBus DP

FieldBus communication format. ProfiBus was created in 1989 by the

German government in cooperation with several manufacturers of

automation equipment. It is a messaging format specifically designed for

high-speed serial I/O in factory and building automation applications. It is an

open standard and is recognized as the fastest FieldBus in operation today.

It is based on RS485 and the European EN50170 Electrical Specification.

The DP suffix refers to “Decentralized Periphery”, which is used to describe

distributed I/O devices connected via a fast serial data link with a central

controller. To contrast, a programmable logic controller (PLC) normally has

its input/output channels arranged centrally. By introducing a network bus

between the main controller (master) and its I/O channels (slaves), we have

decentralized

the I/O.

ProfiBus is based on universal international standards and oriented to

the OSI (Open System Interconnection) reference model per international

standard ISO 7498. In this model, every layer handles precisely defined

tasks. Layer 1 of this model is the physical layer and defines the physical

transmission characteristics. Layer 2 is the data link layer and defines the

bus access protocol. Layer 7 is the application layer and defines the

application functions. ProfiBus DP uses only layers 1 & 2 of this model, plus

the user interface. Layers 3 to 7 are not used.

A ProfiBus system uses a bus

master

to poll

slave

devices distributed in

multi-drop fashion on an RS485 serial bus. A ProfiBus slave is any

peripheral device (I/O transducer, valve, network drive, or other measuring

device) which processes information and sends its output to the master.

The slave forms a “passive station” on the network since it does not have

bus access rights, and can only acknowledge received messages, or send

response messages to the master upon request. It is important to note that

all ProfiBus slaves have the same priority, and all network communication

originates from the master. Acromag I/O modules form intelligent

slave

devices.

Acromag modules implement the ProfiBus protocol via an industry-

standard SPC3 ASIC from Siemens. This ASIC acts like a RAM or UART

chip to the internal microcontroller and completely handles the requirements

of the protocol standard. The ASIC will transfer network data to and from

the microcontroller and automatically provide the response to the bus

according to the ProfiBus specification.

ABOUT PROFIBUS

1 2 3 4 5 6 7 8 ... 37 38

Comments to this Manuals

No comments

Siemens SPC3 Specifications Page 3

Comments to this Manuals

Related products and manuals for Networking Siemens SPC3