Mitsubishi Electric MELSEC iQ-F Series User Manual page 55

• For TLS connection
FX5 CPU module
(ladder program)
FB: MQTT_Connect FB: MQTT_Connect
i_bConnect=OFF→ON i_bConnect=OFF→ON
FB: MQTT_Connect: output FB: MQTT_Connect: output
o_bOK=ON o_bOK=ON
To use TLS connection, the MQTT client performs a TLS handshake before sending the CONNECT command. During the
handshake, the client and broker exchange their certificates with each other. The client and broker must be configured in
advance to trust each other's certificates.
When the TLS handshake is completed, the MQTT client sends the CONNECT command. The broker receives the
CONNECT command, performs authentication by using the client certificate and device ID exchanged during the TLS
handshake, and then returns CONNACK, which means that now a session is established. Generally, when using TLS
connection, TCP port 8883 is used. Other ports can be used if they are supported by the broker.
When a firewall is set up between this Ethernet module and the Internet, permission must be given to a port to be used. Set
permission according to the instructions by the system administrator.
Ethernet module
TLS Handshake (Certificate) TLS Handshake (Certificate)
CONNECT (ClientID) CONNECT (ClientID)
CONNACK CONNACK
Cloud
Broker
4 FUNCTION LIST
53
4.3 Other Functions
4