6 The network Net
6.1 Introduction network Net
274
Control Relay easy800
11/11 MN04902001Z-EN
www.eaton.com
Only the physically first NET station that is located at the beginning of the
network manages the configuration and commissioning of the NET. In this
way, the commissioning of NET stations is very simple. Apart from the
installation with prefabricated cables, this only requires the following for the
standard “passing through” cable routing:
•
Definition of the first NET station by assigning NET ID 1 and the possible
necessary modification of the baud rate in the NET PARAMETERS menu.
•
Creation of the station list with automatic assignment of the NET IDs for
the connected devices in the STATION menu.
•
Configuration via the CONFIGURATION menu.
Further information on the configuration of the NET can be found on Page 94.
Commissioning is even simpler when using easySoft-Pro. Information on this
is provided in the Online Help of easySoft-Pro.
Transfer behavior of the NET stations
In addition to the process that runs the program, a device with a NET
connection also runs a parallel communication process that controls the
exchange of network data.
Before every program cycle the network data is written from the NET receive
buffer to the process image of the program. The program runs through the
next cycle with this data. At the end of the program cycle, the updated
network data is written from the process image to the NET send buffer and
then transferred.
Reading and sending the data via the NET
The communication process of a NET station reads every message on the
NET and checks whether any messages are meant for its own address
(NET ID). If yes, they are transferred to a receive memory.
If the content of the send memory changes, a message is sent provided that
no other message is being transferred on the NET at this time. The NET
ensures that each station can send its messages. This means that each
station must maintain a delay time between the sending of messages.
The pause time increases the higher the number of stations and the lower
baud rate setting.
The number of NET stations present is recognized by every station by means
of a “sign of life” signal.
DANGER
Ensure that the automatic starting of easy800 will not cause the
unwanted starting of machines and plants.
