subscribe mqtt issue ThingsBoard[python]

我创建了一个设备，并将其链接到仪表板中的控制小部件（简单按钮true或false）。然后thingsboard将这些信息发送给thingsboard经纪人。然后我希望我的pycom硬件订阅我的控件小部件的真假主题。所以几周前写了这段代码，这段代码很有效，但现在不再有效了。我一句话也没改。在工作方式上是否有我不知道的变化？有人能帮我吗

代码如下：

server = 'demo.thingsboard.io'
port = 1883
pw_light='' #access token light
id = ''
topic_subscribe='v1/devices/me/rpc/request/+'
topic_publish='v1/devices/me/telemetry'

client_light = MQTTClient(id, server, port,pw_light,pw_light)
client_light.connect()


def sub_cb_red(topic,msg):

    print((topic, msg))
    if msg == b'{"method":"setValue","params":true}':
        chain.show(allred)
    if msg == b'{"method":"setValue","params":false}':
        chain.show(null)

def subscribe_thread(self,n):
  self.subscribe(topic_subscribe,n)

client_light.set_callback(sub_cb_red)
gc.collect()

_thread.start_new_thread(subscribe_thread,(client_light,0))