Network protocol

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Underlying technologyData transmissionNetwork protocol

 

Network protocols are used to exchange data between several connected data processing systems. These are based on the cicon2 OSI layer model which defines various tasks.

 

Network protocols can only be analysed by specially trained experts in the respective protocol, which is why we only list a few sample protocol structures. For more detailed information, please refer to the description of the respective protocol.

 

Click to expand or collaps information.  Profibus

The Profibus network protocol only defines layers 1, 2 and 7 of the OSI model. Three versions of the Profibus exist.

1.DP (decentralised periphery) for the control of sensors and actuators.

2.PA (process automation) for the communication between measuring and processing devices, actuators and process control systems (SPS/DCS).

3.FMS (Fieldbus message specification) for the communication in complex plants. Was replaced by DP and is no longer part of the standard.

 

Protocol structure for DP version:

OSI layer

Protocol / standards

7

DP-V0

DP-V1

DP-V

6

-.-

5

4

3

2

FDL

1

EIA-485

Optical

MBP

 

Data structure FDL:

Telegram type

Coding

Structure

No data

SD1=0x10

SD1 | DA | SA | FC | FCS | ED

Data of variable length

SD2=0x68

SD2 | LE | LEr | DA | SA | FC | PDU | FCS | ED

Data of fixed length

SD3=0xA2

SD3 | DA | SA | FC | PDU | FCS | ED

Token

SD4=0xDC

SD4 | DA | SA

Brief acknowledge

SC=0xE5

SC

 

SD

Start delimiter, used to identify which data telegram should be used.

LE

Length of data; specifies the number of data bytes sent.

LEr

Length of data; repeated for verification purposes.

FC

Functions Code,

DA

Destination address of the data recipient.

SA

Source address, address of sender.

PDU

Protocol Data Unit, data to be transmitted.

FCS

Frame Check Sequence, check sum data.

ED

End delimiter, end byte of the data telegram.

 

 

Click to expand or collaps information.  Profinet

 

OSI layer

Protocol / standards

7a

IO services and protocols

CBA services and protocols

7b

RPC

DCOM & RPC

6

-.-

5

4

UDP

TCP

3

IP | ARP | SNMP | DHCP

2

CSMA/CD | VLAN | DCP | MRP | MRRT | LLDP

1

100BASE-TX | 100BASE-FX

 

 

Click to expand or collaps information.  Ethernet TCP/IP

 

OSI layer

Protocol / standards

7

HTTP

IMAP

SMTP

DNS

.....

6

-.-

5

4

TCP

UDP

3

-.-

2

IP (IPv4, IPv6)

1

Ethernet e.g. IEEE 802.3

 

See also:

Kapitelseite OSI layer model

 

 

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