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5.1Application Architecture
Base on the different requirements of network application this module
provides two operating modes –Server Mode and Client Mode.
When operates at server mode, the Ethernet module will wait for the
message coming from the network. After decode the received message it
will send the message thru serial port to the PLC main unit. The reply
message from the PLC will intercept by this module and packed into data
packet then transmit to the network hence complete a server mode
transaction.
When operates at client mode, the Ethernet module will wait for the
message coming from the serial port. If the received message is for the
PLC located at the remote site connected by network, the Ethernet
module will pack the message into data packet for network transmission
and send it to network. After send the message to network the Ethernet
module will wait for the reply message coming from network, when it
receives the reply message it will direct the message to serial port for
PLC hence complete a client mode transaction. The network connection of
Ethernet module depicted in the figures at following chapter, for clarity,
will only be drawn by a direct link. Actually the network interface of the
Ethernet module is 10BaseT, which should attach with Hub in order to
connect with network.
5.1.1 Server Mode
When operates at server mode, the direct connected single PLC or
the stations connected by RS485 are all work at slave mode, which
will wait for command message passively and reply the command.
Follows are example of server mode application
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