Data Exchange - WAGO 750 Series Manual

66 • Fieldbus Controller 750-841

Data Exchange

3.1.6 Data Exchange
The ETHERNET TCP/IP fieldbus controller can be configured for either
MODBUS/TCP or the Ethernet IP protocol.
MODBUS/TCP works according to the master/ model. The master (e.g., a PC
or a PLC) will query a slave device and the slave will return a response to the
master depending on the kind of query. Queries are addressed to a specific
node through the use of the IP address.
Typically, the ETHERNET TCP/IP controller of the WAGO-I/O-SYSTEM is
a slave device. But, with the use of the WAGO-I/O-PRO CAA programming
tool, the PFC can additionally perform master functions.
A controller is able to produce a defined number of simultaneous socket
connections to other network subscribers:
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The maximum number of simultaneous connections may not be exceeded. If
you wish to establish further connections, terminate an existing connection
first.
For data exchange, the ETHERNET TCP/IP fieldbus controller uses three main
interfaces:
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Data exchange takes place between the fieldbus master and the I/O modules,
between the PLC functionality of the controller and the I/O modules as well as
between the fieldbus master and the PLC functionality of the controller.
Currently, the 750-841 supports MODBUS/TCP and ETHERNET IP based
master devices. When the controller performs PLC functions, and controls
various I/O modules, this is done with the use of an IEC 61131-3 application
program, whereby the data addressing is different than the fieldbus addressing.
3 connections for HTTP (read HTML pages from the controller),
15 connections via MODBUS/TCP (read or write input and output data
from the controller),
128 Ethernet IP connections,
5 connections via the PFC (available for IEC 61131-3 application
programs)
2 connections for WAGO-I/O-PRO CAA (these connections are reserved
for debugging the application program via ETHERNET.
For debugging, WAGO-I/O-PRO CAA requires 2 connections at the same
time. However, only one programming tool can have access to the
controller.
10 connections for FTP
2 connections for SNMP
interface to the fieldbus (master),
the PLC functionality of the PFCs (CPU) and
the interface to the I/O Modules.
WAGO-I/O-SYSTEM 750
ETHERNET TCP/IP