Senatek LS100 manual TCP Client Mode Operations, Operations Serial data transfer

4.2 TCP Client Mode Operations

4.2.1 Overview

The LS100 works as a TCP client, and the default TCP state is [Closed] in this mode. The remote host will be either Ethernet-Serial communication devices acting as a TCP server or a socket program acting as a TCP server running on users’ PC.

1) Typical State Transition

[Closed] -->[Sync-Sent] -->[Established] -->[Data] -->[Closed]

At start-up, an initial TCP state is [Closed]. If there is any incoming data through the serial port, the LS100 will try to connect to a user-defined remote host. Then, the state will be changed to [Sync-Sent], which means the connection request is being sent. If the remote host accepts the request, the state will be changed into [Established], which means a session has been opened. For a while, data will be transferred between the hosts. This is [Data] state. The session will be disconnected due to the request of one of them, which is its original state, [Closed].

2) Operations

Serial data transfer

Whenever the serial device sends data through the serial port of the LS100, data will be accumulated to the serial port buffer of the LS100. If the internal serial port buffer is full or inter- character time interval reaches to the time specified as inter-character timeout value, it tries to connect to the user-defined IP address of the remote host, if TCP session is not established yet. If the LS100 succeeds in connecting to the remote host, the data in the serial port buffer will be transferred to the host. Otherwise, all the data stored in the buffer will be cleared.

Session disconnection

The connected session will be disconnected when the remote host sends disconnection request or when no data transfer activity is found through the serial port for certain amount of time, which is “Inactivity timeout”. All the data remained in the serial port buffer will be cleared when it is disconnected.

Connection request from remote host

All the incoming TCP connection requests will be rejected in TCP client mode.

Cyclic Connection

It Cyclic Connection function is enabled, the LS100 will make an attempt to connect to the user- defined remote host at certain interval even if there’s no incoming serial data from the device. If the remote host prepares certain data, it will be transferred to the serial device via its serial port

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