Tcp/Ip Communications, Udp/Ip Communications; Establishing A Connection; When The Ethernet-Equipped Module Is Passive Open; Appendix 5 Tcp/Ip Communications, Udp/Ip Communications - Mitsubishi Electric MELSEC iQ-RJ71EN71 User Manual

Appendix 5
This chapter describes the communication flow and procedure of TCP/IP communications and UDP/IP communications.
TCP/IP communications
This section describes TCP/IP communications.

Establishing a connection

With TCP/IP communications, a connection must be established between the communicating devices. If the server side
device has executed the Passive open processing and is in the standby state, the client side device makes an open request
(Active open processing) to the server. When a response is returned, the connection is established.
With TCP/IP communications, a connection is established during communication. Since data is exchanged while checking
that the data has correctly reached the communication destination, the data reliability can be ensured. Note that the line load
is larger than UDP/IP communications.
Ex.

When the Ethernet-equipped module is Passive open

Server
Ethernet-equipped module
Passive open
APPX
378

Appendix 5 TCP/IP Communications, UDP/IP Communications

TCP/IP Communications, UDP/IP
Communications
Open request
Response
Connection
Client
External device
Active open