diff --git a/DroneSimulator/Drone.cs b/DroneSimulator/Drone.cs
index 6095c97..dcc303e 100644
--- a/DroneSimulator/Drone.cs
+++ b/DroneSimulator/Drone.cs
@@ -155,13 +155,14 @@ namespace DroneSimulator
               if (drone.StepTime > 0)
               {
                 uint tick = Tick();
-                uint step = drone.Timer + drone.StepTime;
+                uint prev = drone.Timer;
+                uint step = prev + drone.StepTime;
 
                 if (TimeLimit && (step > tick)) step = tick;
 
                 drone.Action(step);
                 drone.StepTime = 0;
-                drone.SendStep(step);
+                drone.SendStep(step, prev);
                 break;
               }
             }
@@ -377,16 +378,17 @@ namespace DroneSimulator
       AccPRY.Z = ((ul + dr) - (dl + ur)) / 4;
     }
 
-    private void SendStep(uint time)
+    private void SendStep(uint time, uint prev)
     {
       DroneData.Step step = new DroneData.Step();
 
-      step.Head.Size = Marshal.SizeOf(typeof(DroneData.DataAcc));
+      step.Head.Size = Marshal.SizeOf(typeof(DroneData.Step));
       step.Head.Mode = DroneData.DataMode.Response;
       step.Head.Type = DroneData.DataType.Step;
       step.Head.Time = Tick();
 
       step.StepTime = time;
+      step.PrevTime = prev;
 
       byte[] bytes = getBytes(step);
 
diff --git a/DroneSimulator/DroneData.cs b/DroneSimulator/DroneData.cs
index d6b1f94..a9689f2 100644
--- a/DroneSimulator/DroneData.cs
+++ b/DroneSimulator/DroneData.cs
@@ -1,5 +1,4 @@
-using System.Net;
-using System.Runtime.InteropServices;
+using System.Runtime.InteropServices;
 
 namespace DroneData
 {
@@ -9,8 +8,8 @@ namespace DroneData
   };
 
   public enum DataType : ushort
-  { 
-    Ping = 0, Step = 1,
+  {
+    None = 0, Ping = 1, Step = 2,
 
     // Output
     DataAcc = 1001, DataGyr = 1002, DataMag = 1003, DataRange = 1004, DataLocal = 1005, DataBar = 1006, DataOF = 1007, DataGPS = 1008,
@@ -39,8 +38,9 @@ namespace DroneData
     public DataHead Head;
 
     public uint StepTime; // ms, запрос: шаг работы симулятора; ответ: Последнее время изменения данных
+    public uint PrevTime; // ms, ответ: Предпоследнее время изменения данных
 
-    static public int StrLen = Marshal.SizeOf(typeof(DroneData.DataAcc));
+    static public int StrLen = Marshal.SizeOf(typeof(DroneData.Step));
   }
 
   public struct XYZ { public float X, Y, Z; }