PROGRAM mqtt_client
VAR

    //----------------- Connection ------------------------
    Mqtt_Client     : MQTT.MQTTClient;
    sHostname       : STRING(255) := '';  // Hostname or ip address or URL (for WebSockets: ws:// or wss://)
    Port            : UINT := 12345;     // Port of the MQTT broker
    sUsername       : WSTRING(255):="";
    sPassword       : WSTRING(255):="QxDsfQ4hS-KcCZxia0W5cw";
    eCommunicationMode : MQTT.COMMUNICATION_MODE := MQTT.COMMUNICATION_MODE.TCP; // Communication mode: TCP/IP or WebSockets
    eMQTTVersion    : MQTT.MQTT_VERSION := MQTT.MQTT_VERSION.V3_1_1; // The MQTT protocol version
    sWillMessage    : STRING(1024);     // The last will message
    sWebSocketUrl   : STRING(255) ;
    // Example of connect properties (V5 only)
    mQTTConnectProperties : MQTT.MQTTConnectProperties := (
        udiSessionExpiryInterval := 10,
        udiMaximumPacketSize := MQTT.MQTTParam.g_udiMaxPacketSize,
        userProperties := 
            [
                (wsKey := "key1", wsValue := "value1"),
                (wsKey := "key2", wsValue := "value2"), 
                (wsKey := "key3", wsValue := "value3")
            ]
    );


    DiagMsg_1       : STRING;
    xError_1        : BOOL;
    Connected       : BOOL;

    //----------------- Publish ------------------------
    Mqtt_Publish    : MQTT.MQTTPublish; 
    sTopicPublish   : WSTRING(1024) := "NeXo"; // Topic to publish a message
    pDone           : BOOL;
    pError          : BOOL;
    eTupe           : MQTT.MQTT_ERROR;
    eError: MQTT.MQTT_ERROR;
    length: INT;
    length1: UINT;


    message_1       : STRING:='';     // Message to publish in JSON format
    message_2       : STRING;     // Message to publish in JSON format
    message_3       : STRING;     // Message to publish in JSON format
    message_4       : STRING;     // Message to publish in JSON format
    message_5       : STRING;     // Message to publish in JSON format
    message_6       : STRING;     // Message to publish in JSON format
    message_7       : STRING;     // Message to publish in JSON format
    message_8       : STRING;     // Message to publish in JSON format
    message_9       : STRING;     // Message to publish in JSON format
    message_10      : STRING;     // Message to publish in JSON format



    sState          : BOOL;
    sState1         : BOOL;
    sState2         : BOOL;
    sState3         : BOOL;
    sState4         : BOOL;
    sState5         : BOOL;
    sState6         : BOOL;
    sState7         : BOOL;
    sState8         : BOOL;
    sState9         : BOOL;
    sState10        : BOOL;

    state           : WORD;

    //----------------- Subscribe -----------------------
    MQTT_Subscribe  : MQTT.MQTTSubscribe;
    wsSubcribeTopicFilter : WSTRING(1024) := "maxbess"; // Topic filter to subcribe a topic
    Subs_msg        : STRING;
    msg_size        : UDINT;
    sDone           : BOOL;
    sError          : BOOL;
    Error_num       : MQTT.MQTT_ERROR;

END_VAR

--------------------------------------------------------------------------------

Mqtt_Client(xEnable:=TRUE,
            sHostname:=sHostname,
            sWebSocketUrl:=sHostname,
            uiPort:=Port,
            wsUsername:=sUsername,
            wsPassword:=sPassword,
            //pbWillMessage:=ADR(sWillMessage),
            //uiWillMessageSize:=DINT_TO_UINT(Stu.StrLenA(ADR(sWillMessage))),
            eCommunicationMode:=eCommunicationMode,
            eMQTTVersion:=eMQTTVersion,
            //mQTTConnectProperties:=mQTTConnectProperties,
            eMQTTError=>eError,
            xConnectedToBroker=>Connected,
            xError=>xError_1);

Mqtt_Publish(xExecute:=PLC_PRG.CLK_500ms,
             udiTimeOut:= 1000000,
             pbPayload:= ADR(message_1),
             udiPayloadSize:=INT_TO_UINT(LEN(message_1)),
             mqttClient := Mqtt_Client,
             wsTopicName:= sTopicPublish,
             xDone=> pDone,
             xError=>pError,
             eMQTTError=>eTupe);


MQTT_Subscribe(xEnable:= plc_prg.CLK_1s,
              pbPayload:=ADR(Subs_msg),
              udiMaxPayloadSize:= SIZEOF(Subs_msg),
              mqttClient:= Mqtt_Client,
              wsTopicFilter:=wsSubcribeTopicFilter,
              udiPayloadSize => msg_size,
              xDone => sDone,
              xError=> sError,
              eMQTTError=> Error_num);
code