Technical data

Fieldbus Communication • 173
ETHERNET
WAGO-I/O-SYSTEM 750
BACnet/IP Controller
Deterministic ETHERNET
The TCP/IP software or the user program in each subscriber can limit
transmittable messages to make it possible to determine real-time require-
ments. At the same time the maximum medium message rate (datagrams per
second), the maximum medium duration of a message, and the minimum
time interval between the messages (waiting time of the subscriber) is lim-
ited.
Therefore, the delay time of a message is predictable.
Switched ETHERNET
In the case of Switched ETHERNET, several fieldbus nodes are connected by
a switch. When data from a network segment reaches the switch, it saves the
data and checks for the segment and the node to which this data is to be sent.
The message is then only sent to the node with the correct target address.
This reduces the data traffic over the network, extends the bandwidth and
prevents collisions. The runtimes can be defined and calculated, making the
Switched ETHERNET deterministic.
Fig. 4-7: Principle of Switched ETHERNET G012909e