IEC61499 应用程序－MQTT publish/subscribe

4diac-IDE 和forte 运行时支持MQTT .

IEC61499 应用程序

subscribe 功能块的ＩＤ为

　

fbdk[].mqtt[tcp://localhost:1883, forte,input]

publish 功能块的ＩＤ为

fbdk[].mqtt[tcp://localhost:1883, forte,output]

 值得注意的是这里使用了fbdk[] ,他在MQTT message.payload　中采用的是ASN.1 编码方式。这里　４个整形数。payload 的格式为

　0x43 0x00 0x00 0x43 0x00 0x00 0x43 0x00 0x00

MQTT broker 使用mosquitto ,在运行程序之前需要运行该程序。方法有两种

sudo mosquitto 

sudo service mosquitto start

为了仿真一个外部的ＭＱＴＴ应用。编写了一个python 应用程序.这个程序什么都没有做，只是将三个数循环加１

import time

import paho.mqtt.client as mqtt
# The callback for when the client receives a CONNACK response from the server.
def bytesToHexString(bs):
    return ''.join(['%02X ' % b for b in bs])  
def on_connect(client, userdata, flags, rc):
    if rc == 0:
        print("连接成功")
        print("Connected with result code " + str(rc))
data=bytearray(12)

def on_message(client, userdata, msg):
    #pprint(msg.topic + " " + bytesToHexString(msg.payload))
    for i in range(12):
        data[i]=msg.payload[i]
    data[2]=data[2]+1
    if data[2]==255:
        data[2]=0
    data[5]=data[5]+1
    if data[5]==255:
        data[5]=0
    data[8]=data[8]+1
    if data[8]==255:
        data[8]=0
    data[11]=data[11]+1
    if data[11]==255:
        data[11]=0
    print(msg.topic + " " + bytesToHexString(data))
    client.publish(topic="input", payload=bytes(data), qos=1, retain=False)
  
client = mqtt.Client(protocol=3)
 
client.on_connect = on_connect
client.on_message = on_message
client.connect(host="localhost", port = 1883, keepalive=60)  # 订阅频道
time.sleep(1)
# client.subscribe("public")
client.subscribe([("output", 0), ("test", 2)])
client.loop_forever()