diff --git a/src/src/main/java/com/my/graphiteDigesterBg/diframe/DiCommandRequest.java b/src/src/main/java/com/my/graphiteDigesterBg/diframe/DiCommandRequest.java
index 9b794be..dcb4bf4 100644
--- a/src/src/main/java/com/my/graphiteDigesterBg/diframe/DiCommandRequest.java
+++ b/src/src/main/java/com/my/graphiteDigesterBg/diframe/DiCommandRequest.java
@@ -1,8 +1,9 @@
 package com.my.graphiteDigesterBg.diframe;
 import java.nio.ByteBuffer;
 import java.util.Timer;
-
 public class DiCommandRequest {
+    // id counter
+    private static int idCounter = 0;
     // message id
     public short id;
     // parameter
@@ -19,4 +20,17 @@ public class DiCommandRequest {
     public Integer timeoutCount = 0;
     // timeout timer
     public Timer timeoutTimer = null;
+
+    // constructor
+    public DiCommandRequest() {
+        this.refreshId();
+    }
+
+    // refresh id
+    public void refreshId() {
+        this.id = (short)idCounter++;
+        if ( idCounter > 30000 ) {
+            idCounter = 0;
+        }
+    }
 }
diff --git a/src/src/main/java/com/my/graphiteDigesterBg/diframe/DiDevice.java b/src/src/main/java/com/my/graphiteDigesterBg/diframe/DiDevice.java
index 2392a7f..f339e3d 100644
--- a/src/src/main/java/com/my/graphiteDigesterBg/diframe/DiDevice.java
+++ b/src/src/main/java/com/my/graphiteDigesterBg/diframe/DiDevice.java
@@ -35,15 +35,11 @@ public class DiDevice {
     private DiTaskManager taskManager;
     // runtime variables
     private DiDeviceRuntimeVariableManager runtimeVariables;
-    // message index
-    private short messageIndex = 0;
     // testcase manager
     private DiTestcaseManager testcaseManager;
 
     @PostConstruct
     public void init() {
-        this.messageIndex = 0;
-
         this.loadDeviceYml();
         this.setupConnection();
         this.io = new DiDeviceIOManager(this);
@@ -227,10 +223,9 @@ public class DiDevice {
         int moduleId = mid;
 
         DiCommandRequest request = new DiCommandRequest();
-        request.id = this.messageIndex;
         request.parameter = ByteBuffer.allocate(length);
         request.parameter.order(ByteOrder.LITTLE_ENDIAN);
-        request.parameter.putShort(this.messageIndex);
+        request.parameter.putShort(request.id); // packet index
         request.parameter.putShort((short)mainCmdId); // main cmd id
         request.parameter.put((byte)subCmdId); // sub cmd id
         request.parameter.put((byte)0); // directive type
@@ -241,11 +236,6 @@ public class DiDevice {
             }
         }
 
-        this.messageIndex ++;
-        if ( this.messageIndex > 30000 ) {
-            this.messageIndex = 0;
-        }
-
         return request;
     }