Advanced Settings to Optimize Serial to Ethernet Applications

Serial to Ethernet Device Servers have become one of the most popular equipment in the industrial world. It converts the serial data such as RS-232 or RS-422/485 to the Ethernet, which allows users to access/monitor the serial devices over the existing Ethernet / Internet network. Most users are familiar with the basic functions like virtual com port or TCP Server/Client. There are more functions which can optimized the serial applications performance.

Serial / Delimiter Function

The serial data may contain a specific character in the data stream. When the device server receives the "specific character" through its serial port, it immediately packs all data in the buffer and sends it out through the Ethernet port.

  • Use the Delimiter function to ensure the serial data is packed into the same Ethernet packet.

Example 1, if set delimiter1 is 44, 44 is D in ASCII code and set blank in delimiter2. The serial port will not send out the data to the Ethernet port before the serial port can receive character D. After receiving D the serial port sends out the data to the Ethernet port directly.

Example 2, if set delimiter1 is 44 and delimiter2 is 4D, of course 4D in ASCII code is M. The serial port will not send out the data to the Ethernet port before the serial port receives the sequence character DM.

Example 3, we keep the DM example; the serial port will still keep the characters ABDEM in the buffer of the NPort after the serial port sends out a portion of the serial data to the Ethernet port.

  • If the delimiter is not receiving data, it will keep buffering. When the buffer gets full, it will send all the data


Force Transmit
The Force Transmit function forces the device server to pack serial data into the same data frame during the specified time.

  • The Force Transmit is just the interval timeout between characters.
  • It will calculate the interval time between these two parts of the characters. But the device server will transfer data stored in the buffer via TCP/IP, but only when the internal buffer is full or has an inter-character interval timeout.


Packet Length
The Packet Length function uses a specified packet length to decide the following conditions:

  • If the application requires receiving an Ethernet packet with every two bytes of data from serial devices, enable this function and configure it as 2 bytes. Hence the packet length will force the device server to send out serial data with the specified packet length.
  • The maximum size for defining packet length is upon the models and manufactures.


Inactivity Timeout
The Inactivity Timeout function automatically closes the device server's TCP connection if there is no serial data activity for the given time. It frees up the device server if there is no serial data activity in order to allow the device server to establish another TCP connection, and work more efficiently


TCP Client Mode Connection Control

  • Start / None: A TCP connection will be established on startup, and will remain active indefinitely
  • Any Character / None: A TCP connection will be established when any character is received from the serial interface, and will remain active indefinitely.
  • Any Character / Inactivity Time: It will be disconnected when Inactivity time is reached.
  • DSR ON / None: A TCP connection will be established when a DSR signal is “On” and will remain active indefinitely.
  • DSR ON / DSR OFF: A TCP connection will be established when a DSR signal is “On” and will be disconnected when a DSR “Off” signal is received.

Both “DCD ON / None” and “DCD ON / DCD OFF” modes are the same as the previous “DSR ON / None” and “DSR ON / DSR OFF” modes. The only difference is the signal type.

TCP Alive Check Time
This function gives the device server a fail-safe mechanism if the network is disconnected or the remote computer is in panic mode.

For example, the Ethernet connection (step 1) will establish a connection. Then if host1 crashes or the network link is broken, if the timeout is exceeded, it will close the port and go back to a listen status.


These serial to Ethernet advanced functions will assist the users to optimize the performance of their serial applications. Let us know if you have any questions. Click here for the products which are comparable to optimize your serial application.

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