Lenze I/O system 1000 System Manual - Manual (Page 713)

Modbus TCP Kommunikation
About Modbus TCP
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713 EDSIO1000 EN 7.0
13 Modbus TCP communication
13.1 About Modbus TCP
Typical fieldbus systems are divided into master and slave systems. Master systems are CPs
coupled to the CPU that which allow remote programming and visualisation of the
corresponding CPU and a data exchange between several TCP/IP nodes.
Slave systems are "data collectors" which provide the requesting master with the I/O data
of the connected modules.
The Modbus TCP bus coupler module described here is a slave system. Since, however,
communication is executed out via TCP/IP, the slave system is called server and the master
is called client.
The Modbus TCP bus coupler module serves to connect up to 64 I/O compound modules
via Ethernet. Up to 8 clients can communicate simultaneously with the bus coupler.
Automatic address mapping
After switch−on, the bus coupler module identifies the I/O compound modules connected
via the backplane bus and adds them to the address range. Address mapping provides one
area for input data and one area for output data. The integrated web server provides access
to the current mapping. Here, you can also parameterise your modules.
Communication
The Modbus TCP bus coupler module is connected to the I/O compound modules via the
backplane bus. It collects their data and makes them available as "server" (slave) to a
higher−level "client" (master system).
Communication is executed via TCP/IP Modbus TCP protocol where TCP/IP packets are
transmitted. In reverse, the bus coupler module receives the data addressed via IP address
and port and transmits them to its output peripherals.
Protocols
Protocols define regulations or standards for communication. A generally accepted model
for the standardisation of the complete computer communication is the ISO/OSI layer
model consisting of seven layers which manage the use of hardware and software.
Layer Function Protocol
7 Application layer Modbus TCP
6 Presentation layer
5 Session layer
4 Transport layer TCP
3 Network layer IP
2 Data link layer (protection)
1 Physical layer (bit transmission)