diff --git a/TBF/Rig/ControlBoard/Uni/GeneralData.cs b/TBF/Rig/ControlBoard/Uni/GeneralData.cs
index 55e2cd753..13a5929d5 100644
--- a/TBF/Rig/ControlBoard/Uni/GeneralData.cs
+++ b/TBF/Rig/ControlBoard/Uni/GeneralData.cs
@@ -13,6 +13,8 @@ namespace TBF.Rig.ControlBoard.Uni
         public const int MessageLen = 303;
         public const byte MessageCode = (byte)' ';
 
+        public bool RestartReadingOfWMPulses = true;
+
         /// General data
         public ulong State;                                             /// bytes 5,6,7,8,9,80,81 = 7 bytes = 56 bits
         public uint Chyby485;
@@ -34,6 +36,9 @@ namespace TBF.Rig.ControlBoard.Uni
         public Int16[] AnalogInput = new Int16[Const.ADCsCount];
         public int[] TemperatureRaw = new int[8];
 
+        ///  Private
+        int[] lastPulses = new int[Const.WMsCount + 1];                 /// WMsCount = 20
+
 
         public GeneralData()
         {
@@ -121,7 +126,7 @@ namespace TBF.Rig.ControlBoard.Uni
             RegVStatus[Const.RVsCount + 1] = (stavRegQ >> 4) & 2;
 
             /// This must preceed processing bytes 91 .. 250 as Ttime is used there
-            uint ttimeRaw = GetUInt32(data, offs + (int)Poz.Ttime);             /// Byte 251,252,253,254 
+            uint ttimeRaw = GetUInt32(data, offs + (int)Poz.Ttime);             /// Byte 251,252,253,254
             Ttime = Convert.ToDouble(ttimeRaw) * Const.TimeResolution;          /// convert to [s]
             ImpulseTime[0] = Ttime;
 
@@ -133,7 +138,7 @@ namespace TBF.Rig.ControlBoard.Uni
                 if ((State & (ulong)StatusP.SynchroMethod) != 0)
                 {
                     ushort pulses = GetUInt16(data, ix2);
-                    WMeterPuls[wmNr] = Convert.ToInt32(pulses);
+                    WMeterPuls[wmNr] = GetCorrectedPulses(wmNr, pulses, RestartReadingOfWMPulses);
                     EtPulses[wmNr] = (pulses == 0) ? 0 : Convert.ToInt32(GetUInt24(data, ix1));
                     ImpulseTime[wmNr] = (pulses == 0) ? 0 : Const.TimeResolution * Convert.ToDouble(GetUInt24(data, ix1 + 3));
                 }
@@ -144,6 +149,7 @@ namespace TBF.Rig.ControlBoard.Uni
                     ImpulseTime[wmNr] = Ttime;
                 }
             }
+            RestartReadingOfWMPulses = false;
 
             StavDA[0] = GetUInt16(data, offs + (int)Poz.SDA);                   /// Byte 255,256
             byte spare3 = data[offs + (int)Poz.spare3];                         /// Byte 257
@@ -199,6 +205,44 @@ namespace TBF.Rig.ControlBoard.Uni
             log.InfoFormat("Et={0} State={1:X14} Route={2} Freq={3} EtPulses={4} TTime={5} WMPulses[3]={6} WMRefPulses[3]={7}, Time[3]={8}",
                            (State & 7), State, Utils.ToBin40(((UInt64)Vystupy) >> 8), ReferenceFreq[0], EtPulses[0], Ttime, WMeterPuls[3], EtPulses[3], ImpulseTime[3]);
         }
+
+        /// <summary>
+        /// Get number of pulses corrected for windowing effect
+        /// </summary>
+        /// <param name="wmNr1">1-based water meter number</param>
+        /// <param name="lowerWordOfMeterPulses"></param>
+        /// <param name="firstReading">When true lastPulses[wmNr1] is disregarded and is overwritten with lowerWordOfMeterPulses value</param>
+        /// <returns>Corrected water meter pulses</returns>
+        private int GetCorrectedPulses(int wmNr1, UInt16 lowerWordOfMeterPulses, bool firstReading)
+        {
+            if (firstReading)
+            {
+                lastPulses[wmNr1] = (Int16)lowerWordOfMeterPulses;
+            }
+            else
+            {
+                int uncorrected = (int)(((uint)lastPulses[wmNr1] & 0xFFFF0000) | lowerWordOfMeterPulses);
+
+                if (Math.Abs(uncorrected - lastPulses[wmNr1]) <= Int16.MaxValue)
+                {
+                    lastPulses[wmNr1] = uncorrected;
+                }
+                else if (Math.Abs(uncorrected + 65536 - lastPulses[wmNr1]) <= Int16.MaxValue)
+                {
+                    lastPulses[wmNr1] = uncorrected + 65536;
+                }
+                else if (Math.Abs(uncorrected - 65536 - lastPulses[wmNr1]) <= Int16.MaxValue)
+                {
+                    lastPulses[wmNr1] = uncorrected - 65536;
+                }
+                else
+                {
+                    lastPulses[wmNr1] = uncorrected;    /// Default
+                }
+            }
+
+            return lastPulses[wmNr1];
+        }
     }
 
     /// <summary>
diff --git a/TBF/Rig/ControlBoard/Uni/UniCB.cs b/TBF/Rig/ControlBoard/Uni/UniCB.cs
index 325359909..50e1c8f33 100644
--- a/TBF/Rig/ControlBoard/Uni/UniCB.cs
+++ b/TBF/Rig/ControlBoard/Uni/UniCB.cs
@@ -460,6 +460,11 @@ namespace TBF.Rig.ControlBoard.Uni
                     }
                 }
 
+                if ((combinedAction.ActionId & ActionID.StartTest) != 0)
+                {
+                    Data.RestartReadingOfWMPulses = true;
+                }
+
                 if (cbCfg.DebugLevel == DebugMode.Normal)
                 {
                     serialPort.Write(outData, 0, outData.Length);