User Manual

Table Of Contents
53
III-4-4. MANAGEMENT INDUSTRIAL PROTOCOL
There are two industrial protocols provided in the switch EtherNet/IP and Modbus/TCP.
EtherNet/IP is an industrial network protocol that linked up the Common Industrial Protocol (CIP) with
standard Ethernet. EtherNet/IP takes advantage of both of the Internet Protocol suite and IEEE 802
standard, which are the most widely deployed collections of Ethernet standards, to define the features
and functions for its transportation, networking, data link and physical layers. CIP makes use of
object-oriented design to provide EtherNet/IP with the services and device profiles needed for real-time
control applications. The object-oriented design of the CIP is also used to promote consistent
implementation of automation functions into a diverse ecosystem of products. EtherNet/IP defines how
to organize the data in a TCP/UDP packet and transfers the packet in the application layer.
Modbus is a popular communication protocol used for the industrial serial devices. It is usually working
as “master-slave” architecture and working with programmable logic controllers which are also called
PLCs. The Modbus/TCP implies to provide Modbus Messaging service on the TCP/IP, so that the devices
which are running Modbus can communicate with each other with Modbus messages. The Modbus
messages are encapsulated with an Ethernet TCP/IP wrapper on the basis of the standard. During the
transmission, the switches can only acquire the encapsulated information when the Modbus/TCP is
enabled. If users would like to understand the real content of Modbus message, users have to install
other utilities such as “ModScan”. Our switches implements the Modbus/TCP registers including system
information, firmware information, port information, and packet information. The details refer to the
Modbus Data MAPPING INFORMATION” section”.
MODBUS DATA FORMAT AND FUNCTION CODE
The primary four types of Modbus/TCP data format are as following:
Data Access Type
Function Code
Function Name
Bit Access
Physical Discrete Inputs
2
Read Discrete Inputs
Internal Bits or Physical Coils
1
Read Coils
Word Access
(16-bit Access)
Physical Input Registers
4
Read Input Registers
Physical Output Registers
3
Read Holding Registers