added start and stop time

src/models/tanks.js

@@ -75,7 +75,8 @@ const tanksSchema = new mongoose.Schema({
           manual_threshold_time:{type: String, default: null},
           threshold_type:{type: String, default: "percentage"},
           startTime:{type: String,default:null},
-          real_motor_status:{type:String,default:"1"}
+          real_motor_status:{type:String,default:"1"},
+          stopTime:{type: String,default:null}
         }
       ],
       outputConnections: [