Data Exchange Between Ethernet Ip Master And I/O Modules - WAGO 750 Series Manual

74 • Fieldbus Controller 750-841
Data Exchange

3.1.6.4 Data Exchange between Ethernet IP Master and I/O Modules

Data exchange between the Ethernet IP master and the I/O modules is object
oriented. Each node in the network is represented as a collection of objects.
The "assembly" object defines the structure of objects for data transfer. With
the assembly object, data (e.g. I/O data) can be grouped into blocks (mapped)
and sent via a single communication link. As a result of this mapping
technique, fewer access operations to the network are required.
Input and output assemblies have different functions.
An input assembly reads data from the application over the network or
produces data on the network.
Where as, an output assembly writes data to the application or consumes data
from the network.
Various assembly instances are permanently pre-programmed in the fieldbus
controller (static assembly).
After switching on the power supply, the assembly object maps data from the
process image. As soon as a connection is established, the master can address
the data with "class", "instance" and "attribute" and access or read and/or write
the data via I/O links.
The mapping of the data depends on the chosen assembly instance of the static
assembly.
Further information
The assembly instances for the static assembly are described in the section
7.3.2.6 "Assembly (04 hex)".
WAGO-I/O-SYSTEM 750
ETHERNET TCP/IP