修复S7服务轮询问题

DMS.Application/Models/VariableContext.cs

@@ -6,12 +6,15 @@ namespace DMS.Application.Models
     public class VariableContext
     {
         public VariableDto Data { get; set; }
+        
+        public object NewValue { get; set; }
         public bool IsHandled { get; set; }
 
-        public VariableContext(VariableDto data)
+        public VariableContext(VariableDto data, object newValue=null)
         {
             Data = data;
             IsHandled = false; // 默认未处理
+            NewValue = newValue;
         }
     }
 }