Advantech B+B SmartWorx 232BSS4, Руководство пользователя

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Documentation Number 232BSS4-2916m 19
Figure 2.3 shows a typical setup, with 16 devices sending
information at random times to the PC. The switches at Level 2 receive the
data and send it on to the Level 1 switch. The Level 1 switch buffers the
data and sends it to the PC. Each of the switches will automatically send the
data when it is available. If another port has access to the PC, the data will
be buffered until a path is available.
Slave Devices that Automatically Send their Data:
For best results in an automatic system, the 232BSS4s in the
system should be set up the following way.
•
Set the switches to turn on the Auto Select feature.
•
Set the Port Timer to 0
•
Set the Inactivity Timer on all of the switches to somewhere
between 20 and 500 milliseconds, depending on the space
between data packets and the response time required to
each connected device.
•
If you need your software to identify which port sent the data,
set up the port preamble on the Level 2 switches. Set each
port to have a unique preamble. The preamble can be 1, 2, 3,
or 4 characters long, and any characters can be used. The
preamble will be added to the beginning of each new data
packet arriving at the PC. The data collection software on the
PC should be written to recognize this preamble as an
address or identifier of the data source.