Client.c

#include <stdio.h>
#include "open62541.h"

int main(int argc, char *argv[])
{
    /* Create a client and connect */
    UA_Client *client = UA_Client_new(UA_ClientConfig_default);
    UA_StatusCode status = UA_Client_connect(client, "opc.tcp://localhost:4840");
    if(status != UA_STATUSCODE_GOOD) {
        UA_Client_delete(client);
        return status;
    }

    /* Read the value attribute of the node. UA_Client_readValueAttribute is a
     * wrapper for the raw read service available as UA_Client_Service_read. */
    UA_Variant value; /* Variants can hold scalar values and arrays of any type */
    UA_Variant_init(&value);
    
    //status = UA_Client_readValueAttribute(client, UA_NODEID_STRING(1, "the.answer1"), &value);
    status = UA_Client_readValueAttribute(client, UA_NODEID_NUMERIC(1,20305), &value);
    printf("Status Code is received: 0x%x \r\n",status);
    if(status == UA_STATUSCODE_GOOD &&
       UA_Variant_hasScalarType(&value, &UA_TYPES[UA_TYPES_INT32])) {
        printf(":-) The value is: %i\n\r", *(UA_Int32*)value.data);
    }
    else printf("The value not found :-(\r\n");
    
    /* Clean up */
    UA_Variant_deleteMembers(&value);
    UA_Client_delete(client); /* Disconnects the client internally */
    return status;
}