Xylem Sl Analytics TW 7200 Gebrauchsanleitung Seite 43

5.2
Network communication
By default, address assignment via DHCP is activated on the TW 7200. This automatically assigns an IP address
to the device in an IP network, provided that a DHCP server is active there.
The NWA command can be used to query the current connection parameters as well as to set new connection
parameters. During the initial setup it is recommended to set up the address parameters via RS1 or USB. If a
network connection with a known IP to the TW 7200 is established, the network parameters can also be changed
directly via the network connection.
The UDP (User Datagram Protocol) and TCP (Transmission Control Protocol) protocols are available for direct
communication with the device. The communication itself is ASCII-based with the identical commands from the
RS command list. For this purpose, the command is written into the data field (payload) of the respective
protocol.
The address of the device must still be prefixed despite IP communication. Thus, if required, further devices
connected directly to the DC2 interface can be addressed via the TCP connection of the TW 7200. The control
characters "CR"; "LF" at the end of the command are not necessary here, but are permitted.
Communication via UDP
5.2.1
The UDP protocol is mainly used to find and identify the device in the network. A forwarding of the UDP
commands to DC2 does not take place, the TW 7200 answers the message directly. Even if a TCP connection to
the device is already open, UDP requests are still answered. The following list shows the commands available via
UDP:
Command Description
aaRH Query device identification
aaVE Query software version
aaGS Query serial number
aaGI Query device information
aaNWA Query / set network settings
aaBLINK Identify device = LED 4x green flashing
Send message to the TW 7200
UDP port: 50.000 / Destination IP: Broadcast address (.255) or known IP of TW 7200
Command: From above list (e.g. 03RH)
Receive message from TW 7200
To receive the UDP response, the controlling device must provide a UDP server on port 50,000.
UDP-Broadcast
With the UDP broadcast a packet can be sent to a whole subnet. (e.g.: 192.168.0.1 to 192.168.0.254). However,
the UDP Broadcast traffic does not traverse multiple networks; it is not forwarded outside the local subnet.
If the TW 7200 is in the same local subnet as the control unit (client), a command from the above list can be sent
with the UDP broadcast address (.255), TW 7200 now only responds specifically to the control unit with a UDP
packet with its IP address and the desired response of the command in the payload. Thus the initially unknown IP
address of the TW 7200 can be determined quickly.
Example:
Action UDP Payload
Control unit
03RH
sends
TW 7200
03Ident: TW7200
answers
To receive the answer of the TW 7200 the control device must listen on the UDP port 50.000
Source port Destination port
optional 50.000
optional 50.000
= provide UDP server
Source IP Destination IP
IP Control unit
e.g. 192.168.0.10 e.g. 192.168.0.255
IP TW7200
e.g. 192.168.0.72 e.g. 192.168.0.10
43
xx.yy.zz.255
IP control unit