USC520 / USC540 User Manual www.usconverters.com
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Converters
3.1. Socket A Communication
3.1.1. TCP Client Model
4.1.1 TCP Client Mode
1) Different from UDP mode, in this mode, connection has status of ‘disconnected’ and active.
Connection is still active although USC520/USC540 does not send data.
2) Identify disconnects. After connection built, it sends keepalive searching packet every 15 seconds.
Once there is an interrupt, it can be detected rapidly then make USC520/USC540 disconnect from
former connection and reconnect.
3) It will connect to same source port when USC520/USC540 try to connect server and local port is not
“0”.
4) It supports Synchronous baud rate (Similar RCF2217), which can revise USC520/USC540’s serial
parameter as baud rate accordingly. This function should be combined with USR-VCOM.
5) Under the same LAN, USC520/USC540 must be in the same network segment then can
communicate. If not, USC520/USC540 must be set with right one.
6) Support USR Cloud.
7) Support Modbus TCP function.
8) USC520/USC540 work as TCP Client, it connects to TCP server, Destination IP and port should be
cared. The IP can be device with same LAN, also can be different LAN or cross public network. If it
connects to server cross public network, the server should have public IP.
9) USC520/USC540 work under TCP Client, It connects to the target IP/Port automatically, will not
accept other connection request.
10) As TCP Client, need to set USR-N510’s local port number to be “0 then it can visit server with
randomized port number, so that it can solve unsuccessful re-connection in case server judge
connection status abnormally and shield USC520/USC540 re-connection request.
