add nothing

ModbusDemo/Common/ModualAlarm.cs

@@ -49,13 +49,16 @@ namespace ModbusDemo.Common
         }
         public static async Task vPublishAlarmPackageJson(IMqttClient mqttClient)
         {
-            var message = new MqttApplicationMessageBuilder()
-                                .WithTopic(Form1.sAlarmTopic)
-                                .WithPayload(sAlarmJson)
-                                .WithAtMostOnceQoS()
-                                .WithRetainFlag(false)
-                                .Build();
-            await mqttClient.PublishAsync(message);
+            if (mqttClient.IsConnected == true)
+            {
+                var message = new MqttApplicationMessageBuilder()
+                                    .WithTopic(Form1.sAlarmTopic)
+                                    .WithPayload(sAlarmJson)
+                                    .WithAtMostOnceQoS()
+                                    .WithRetainFlag(false)
+                                    .Build();
+                await mqttClient.PublishAsync(message);
+            }
         }
         public static void vSet_Modual_Alarm(byte byModbusID,ushort usAlarmCodde,bool bSetAlarm,byte byCommFailTimes,params string[] strChannalList)
         {