- •Important Comments
- •Legal Principles
- •Copyright
- •Personnel Qualification
- •Intended Use
- •Symbols
- •Font Conventions
- •Number Notation
- •Scope
- •Important Comments for Starting up
- •Abbreviation
- •The WAGO-I/O-SYSTEM 750
- •Technical Data
- •Manufacturing Number
- •Storage, Assembly and Transport
- •Mechanical Setup
- •Installation Position
- •Total Expansion
- •Assembly onto Carrier Rail
- •Carrier rail properties
- •WAGO DIN Rail
- •Spacing
- •Plugging and Removal of the Components
- •Assembly Sequence
- •Internal Bus / Data Contacts
- •Power Contacts
- •Wire connection
- •Power Supply
- •Isolation
- •System Supply
- •Connection
- •Alignment
- •Field Supply
- •Connection
- •Fusing
- •Supplementary power supply regulations
- •Supply example
- •Power Supply Unit
- •Grounding
- •Grounding the DIN Rail
- •Framework Assembly
- •Insulated Assembly
- •Grounding Function
- •Grounding Protection
- •Shielding (Screening)
- •General
- •Bus Conductors
- •Signal Conductors
- •WAGO Shield (Screen) Connecting System
- •Assembly Guidelines / Standards
- •Fieldbus Controller
- •Fieldbus Controller 750-841
- •Description
- •Hardware
- •View
- •Device Supply
- •Fieldbus Connection
- •Display Elements
- •Configuration and Programming Interface
- •Operating Mode Switch
- •Hardware Address (MAC-ID)
- •Operating System
- •Start-up
- •PLC Cycle
- •Process Image
- •Example of a Process Input Image
- •Example of a Process Output Image
- •Fieldbus specific Process Data Architecture for MODBUS/TCP
- •Digital Input Modules
- •Digital Output Modules
- •Analog Input Modules
- •Analog Output Modules
- •Specialty Modules
- •Data Exchange
- •Memory Areas
- •Addressing
- •Addressing the I/O Modules
- •Address Range
- •Absolute Addresses
- •Data Exchange between MODBUS TCP Master and I/O Modules
- •Data Exchange between Ethernet IP Master and I/O Modules
- •Data Exchange between PLC Functionality (CPU) and I/O Modules
- •Data Exchange between Master and PLC Functionality (CPU)
- •Example MODBUS TCP Master and PLC functionality (CPU)
- •Comparison of MODBUS TCP Addresses and IEC 61131-3 Addresses
- •Starting up an ETHERNET TCP/IP fieldbus node
- •Connecting PC and Fieldbus Node
- •Determining IP Addresses
- •Allocating the IP Address to the Fieldbus Node
- •Testing the Function of the Fieldbus Node
- •Deactivating the BootP Protocol
- •Programming the PFC with WAGO-I/O-PRO CAA
- •WAGO-I/O-PRO CAA library elements for ETHERNET
- •IEC 61131-3-Program transfer
- •Transmission via the Serial Interface
- •Transmission by the Fieldbus
- •Information on the web-based management system
- •LED Display
- •Blink code
- •Fieldbus status
- •Node status
- •Fault Message via Blink Code from the I/O-LED
- •Supply voltage status
- •Fault behavior
- •Fieldbus failure
- •Internal bus fault
- •Technical Data
- •I/O Modules
- •General
- •Digital Input Modules
- •Digital Output Modules
- •Analog Intput Modules
- •Analog Output Modules
- •Counter Modules
- •ETHERNET
- •General
- •Network Architecture – Principles and Regulations
- •Transmission Media
- •Network Topologies
- •Coupler Modules
- •Important Terms
- •Network Communication
- •Protocol layer model
- •Communication Protocols
- •ETHERNET
- •Channel access method
- •IP-Protocol
- •IP Multicast
- •TCP Protocol
- •Application Protocols
- •MODBUS
- •Ethernet/IP
- •BootP (Bootstrap Protocol)
- •HTTP (HyperText Transfer Protocol)
- •DHCP (Dynamic Host Configuration Protocol)
- •DNS (Domain Name Systems)
- •SNTP-Client (Simple Network Time Protocol)
- •FTP-Server (File Transfer Protocol)
- •SNMP V1 (Simple Network Management Protocol)
- •Configuration of SNMP
- •Description of MIB II
- •IpNetToMediaTable
- •Traps
- •SMTP (Simple Mail Transfer Protocol)
- •MODBUS Functions
- •General
- •Use of the MODBUS Functions
- •Description of the MODBUS Functions
- •Function Code FC1 (Read Coils)
- •Function Code FC2 (Read Input Discretes)
- •Function Code FC3 (Read multiple registers)
- •Function code FC4 (Read input registers)
- •Function Code FC5 (Write Coil)
- •Function Code FC6 (Write single register)
- •Function Code FC11 (Get comm event counter)
- •Function Code FC15 (Force Multiple Coils)
- •Function Code FC16 (Write multiple registers)
- •Function Code FC22 (Mask Write Register)
- •Function Code FC23 (Read/Write multiple registers)
- •MODBUS Register Mapping
- •Internal Variables
- •Description of the internal variables
- •Watchdog (Fieldbus failure)
- •Watchdog Register:
- •Diagnostic Functions
- •Configuration Functions
- •Firmware Information
- •Constant Registers
- •Ethernet/IP (Ethernet/Industrial Protocol)
- •General
- •Characteristics of the Ethernet/IP Protocol Software
- •Object model
- •General
- •Classes
- •CIP Common Classes
- •Static Assembly Instances
- •Application examples
- •Test of MODBUS protocol and fieldbus nodes
- •Visualization and control using SCADA software
- •Use in Hazardous Environments
- •Foreword
- •Protective measures
- •Classification meeting CENELEC and IEC
- •Divisions
- •Explosion protection group
- •Unit categories
- •Temperature classes
- •Types of ignition protection
- •Classifications meeting the NEC 500
- •Divisions
- •Explosion protection groups
- •Temperature classes
- •Identification
- •For Europe
- •For America
- •Installation regulations
118 • ETHERNET
Network Communication
5.3 Network Communication
Fieldbus communication between master application and WAGO ETHERNET controller 750-841 can take place using either the MODBUS protocol or Ethernet/IP.
The protocol layer model helps to explain the classification and interrelationships between the communication and application protocols. Afterwards, the individual protocols are explained in detail.
5.3.1 Protocol layer model
Ethernet:
The Ethernet hardware forms the basis for the physical exchange of data. The exchanged data signals and the bus access procedure CSMA/CD are defined in a standard.
(1) |
Ethernet |
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(physical interface, CSMA/CD) |
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IP:
Above the Ethernet hardware is positioned the Internet Protocol (IP). This bundles the data to be transmitted in packets along with sender and receiver address and passes these packets down to the Ethernet layer for physical transmission. At the receiver end, IP accepts the packets from the Ethernet layer and unpacks them.
(2) |
IP |
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(1) |
Ethernet |
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(physical interface, CSMA/CD) |
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TCP, UDP:
a) TCP: (Transmission Control Protocol)
The TCP protocol, which is positioned above the IP layer, monitors the transport of the data packets, sorts their sequence and sends repeat requests for missing packets. TCP is a connection-oriented transport protocol.
The TCP and IP protocol layers are also jointly described as the TCP/IP protocol stack or TCP/IP stack.
b) UDP: (User Datagram Protocol)
The UDP layer is also a transport protocol like TCP, and is arranged above the IP layer. In contrast to the TCP protocol, UDP is not connection oriented. That means there are no monitoring mechanisms for data exchange between sender and receiver.
The advantage of this protocol is in the efficiency of the transmitted data and the resultant increase in processing speed.
Many programs use both protocols. Important status information is sent via the reliable TCP connection, while the main stream of data is sent via UDP.
WAGO-I/O-SYSTEM 750 ETHERNET TCP/IP
ETHERNET • 119
Network Communication
(3) |
TCP, UDP |
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(2) |
IP |
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(1) |
Ethernet |
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(physical interface, CSMA/CD) |
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Application protocols:
Positioned above the TCP/IP stack or UDP/IP layer are correspondingly implemented application protocols that provide services that are appropriate for the application. These are, for example, SMTP (Simple Mail Transport Protocol) for e-mails, HTTP (Hypertext Transport Protocol) for www browsers and some others.
The protocols MODBUS/TCP (UDP) and Ethernet/IP are implemented for use in industrial data communication.
The MODBUS protocol is also positioned directly above TCP (UDP)/IP; Ethernet/IP, on the other hand, basically consists of the protocol layers Ethernet, TCP and IP with an encapsulation protocol positioned above it. This serves as interface to CIP (Control and Information Protocol).
DeviceNet uses CIP in the same way as Ethernet/IP. Applications with DeviceNet device profiles can therefore be very simply transferred to Ethernet/IP.
(4)
(3)
(2)
(1)
Mail client |
WWW browser |
SMTP |
HTTP |
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Application device profiles |
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(e.g. positioning controllers, semi- |
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conductors, pneumatic valves) |
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... |
MODBUS |
CIP application objects library |
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CIP data management services |
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(explicit messages, I/O messages) |
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CIP message routing, connection |
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management |
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... |
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Encapsulation |
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protocol |
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TCP, UDP |
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IP |
Ethernet
(physical interface, CSMA/CD)
CIP
ETHERNET/IP
WAGO-I/O-SYSTEM 750 ETHERNET TCP/IP