Startup and functions
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PHOENIX CONTACT
3-51
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Control of roaming operation using the AP number
Access points and clients change to their default mechanisms if there is no control from the
central control system.
Figure 3-47
"Adv. WLAN/Fast roaming" menu
Roaming list
The roaming list contains all access points to which a connection should be established.
The list is processed in order. The first entry is also used as the first connection attempt.
Modbus/TCP roaming control
Activates the Modbus/TCP API of the client. A PLC can then request the current position in
the roaming list or trigger fast roaming for any entry in the roaming list.
3.5.4.9
Modbus API
Modbus/TCP implementation is based on the following documents, which are available from
http://www.modbus.org:
–
Modbus_Application_Protocol_V1_1a.pdf
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Modbus_Messaging_Implementation_Guide_V1_0a.pdf
A TCP server is implemented on the APs and the clients. The server opens TCP port 502 to
receive requests.
The TCP server implements the functions of a Modbus/TCP slave. The scope of functions
is limited to the following required Modbus "public function codes":
