ABB CL Series, Руководство по применению

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CL-NET network, COM-LINK
serial connection
330
1SVC 440 795 M1100
Transfer behaviour
Network CPU data transfer to program image
The display system network connection is equipped with its
own CPU. Network data can therefore be processed whilst
the program is running. After each program cycle, the status
of the network data is written to the operand image of the
program and the send data is read from the image. The
program runs through the next cycle with this data.
Reading and sending the network data from the CPU
The network CPU of the station reads every message on the
network. If the message is relevant to the station, it is
accepted into a message memory.
If the content of a send message changes, it is sent.
Transmission only occurs when there is no message on the
network.
CL-NET is configured so that every station can send its
messages. This means that the station must observe a pause
time between sending messages. The pause time increases
the higher the number of stations and the lower baud rate
setting.
The number of stations is recognised by every station via a
“sign of life” signal.
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The following applies to fast message transfer:
• Set the fastest possible baud rate to suit the network
length and cable cross-section.
• Fewer messages means faster messages.
• Avoid program downloads during the RUN mode.