What is the difference between TCP and UDP?

TCP and UDP are transport layer protocols, and they are used according to system requirements.

For detail technical information on TCP/UDP, please refer to other articles and books.

In using these protocol in OPC server, each features are described below.

TCP

• Used when reliable communication is required.
• To secure a session with the connected device, connection may not be possible if the port is occupied by other software.
• There is no need to set the number of retries on the OPC server side because it has a retransmission control function.

*When TCP protocol is selected, it is recommended to set the timeout to "31.5 seconds or more" and the retry count to "0" on Ethernet port setting.

UDP

• Used when high speed communication is required.
• To not secure a session with the connected device, one port can communicate with multiple software.
• Packet loss may occur.
• There is no retransmission control function, and retry setting is required.