diff --git a/TBF/Resources/Strings.Designer.cs b/TBF/Resources/Strings.Designer.cs
index 9d095bf57..f5efe87b8 100644
--- a/TBF/Resources/Strings.Designer.cs
+++ b/TBF/Resources/Strings.Designer.cs
@@ -2238,6 +2238,15 @@ namespace TBF.Resources {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Disabled by user.
+        /// </summary>
+        internal static string Head_was_disabled_by_the_user {
+            get {
+                return ResourceManager.GetString("Head_was_disabled_by_the_user", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Header.
         /// </summary>
@@ -3390,15 +3399,6 @@ namespace TBF.Resources {
             }
         }
         
-        /// <summary>
-        ///   Looks up a localized string similar to Disabled by user.
-        /// </summary>
-        internal static string Opto_head_was_disabled_by_the_user {
-            get {
-                return ResourceManager.GetString("Opto_head_was_disabled_by_the_user", resourceCulture);
-            }
-        }
-        
         /// <summary>
         ///   Looks up a localized string similar to Other.
         /// </summary>
diff --git a/TBF/Resources/Strings.resx b/TBF/Resources/Strings.resx
index 3c428994e..ea0768d1a 100644
--- a/TBF/Resources/Strings.resx
+++ b/TBF/Resources/Strings.resx
@@ -1723,7 +1723,7 @@
   <data name="RFID_communication_failed" xml:space="preserve">
     <value>RFID communication failed</value>
   </data>
-  <data name="Opto_head_was_disabled_by_the_user" xml:space="preserve">
+  <data name="Head_was_disabled_by_the_user" xml:space="preserve">
     <value>Disabled by user</value>
   </data>
   <data name="failed_0_1_exclamation" xml:space="preserve">
diff --git a/TBF/Rig/TestMethods/S640Communication/S640CommForm.cs b/TBF/Rig/TestMethods/S640Communication/S640CommForm.cs
index a32cbc0ae..dfc43d3be 100644
--- a/TBF/Rig/TestMethods/S640Communication/S640CommForm.cs
+++ b/TBF/Rig/TestMethods/S640Communication/S640CommForm.cs
@@ -290,7 +290,7 @@ namespace TBF.Rig.TestMethods.S640Communication
                     checkBoxes[i].Checked = false;
                     checkBoxes[i].Enabled = false;
                     pictures[i].BackColor = DisabledColor;
-                    messages[i].Text = Strings.Opto_head_was_disabled_by_the_user;
+                    messages[i].Text = Strings.Head_was_disabled_by_the_user;
                 }
                 else
                 {
@@ -387,7 +387,7 @@ namespace TBF.Rig.TestMethods.S640Communication
                     {
                         /// Opto head was disabled by the user
                         pictures[i].BackColor = DisabledColor;
-                        messages[i].Text = Strings.Opto_head_was_disabled_by_the_user;
+                        messages[i].Text = Strings.Head_was_disabled_by_the_user;
                     }
                     else
                     {
diff --git a/TBF/Rig/TestMethods/iPerlCommunication/iPerlCommunicationForm.cs b/TBF/Rig/TestMethods/iPerlCommunication/iPerlCommunicationForm.cs
index 005d6674a..a5a29269e 100644
--- a/TBF/Rig/TestMethods/iPerlCommunication/iPerlCommunicationForm.cs
+++ b/TBF/Rig/TestMethods/iPerlCommunication/iPerlCommunicationForm.cs
@@ -1,5 +1,5 @@
 ///
-/// Copyright (c) 2015-2020 Sensus Slovensko a.s.
+/// Copyright (c) 2015-2021 Sensus Slovensko a.s.
 ///
 //#define VERIFY_ACTIVE_MODE
 //#define VERIFY_Q2_CORR_RESET
@@ -494,7 +494,7 @@ namespace TBF.Rig.TestMethods.iPerlCommunication
 			}
 
 			WaterMetersCount = iperlHeads.Count;
-            ShuffleTextBoxes(WaterMetersCount, Common.Data.LineSize);
+            ShuffleTextBoxes(WaterMetersCount, ProcessData.LineSize);
 
 			///
 			/// Prepare worker threads, 'rfidPortNrs', 'lastGroup', etc..
@@ -611,19 +611,10 @@ namespace TBF.Rig.TestMethods.iPerlCommunication
 				textBoxesCount = wmsCount;
 			}
 
-            if (checkBoxesEditMode)
+            int count = checkBoxesEditMode ? textBoxesCount : Math.Min(textBoxesCount, iperlHeads.Count);
+            for (int j = 0; j < count; j++)
             {
-                for (int j = 0; j < textBoxesCount; j++) labels[j].Text = string.Format("WM{0}", j + 1);
-                samplePictureBox1.Visible = false;
-                samplePictureBox2.Visible = false;
-                samplePictureBox3.Visible = false;
-                sampleLabel1.Visible = false;
-                sampleLabel2.Visible = false;
-                sampleLabel1.Visible = false;
-            }
-            else
-            {
-                for (int j = 0; j < Math.Min(textBoxesCount, iperlHeads.Count); j++) labels[j].Text = iperlHeads[j].Name;
+                labels[j].Text = (j + 1).ToString();
             }
 
             ResizeDlgToFitEnabledControls();
@@ -648,7 +639,7 @@ namespace TBF.Rig.TestMethods.iPerlCommunication
 
         void Localize()
         {
-            Text = Strings.Water_Meter_States;
+            Text = checkBoxesEditMode ? Strings.Optical_heads : Strings.Water_Meter_States;
 			saveButton.Text = Strings.Save;
 
             sampleLabel1.Text = Strings.Direction_and_pulses_are_OK;
@@ -665,6 +656,17 @@ namespace TBF.Rig.TestMethods.iPerlCommunication
 		{
             Localize();
 
+            if (checkBoxesEditMode)
+            {
+                /// Check box edit mode => Hide explanation of activity colours
+                sampleLabel1.Visible = false;
+                sampleLabel2.Visible = false;
+                sampleLabel3.Visible = false;
+                samplePictureBox1.Visible = false;
+                samplePictureBox2.Visible = false;
+                samplePictureBox3.Visible = false;
+            }
+
             ///
             /// Set checkbox states accroding to iPerlHeads[i].Disabled states
             ///
@@ -677,7 +679,7 @@ namespace TBF.Rig.TestMethods.iPerlCommunication
                     /// iPerl position i+1 is disabled
                     checkBoxes[i].Enabled = checkBoxes[i].Checked = ckbState[i] = false;
                     counters[i].BackColor = DisabledColor;
-                    messages[i].Text = Strings.Opto_head_was_disabled_by_the_user;
+                    messages[i].Text = Strings.Head_was_disabled_by_the_user;
                 }
                 else
                 {
@@ -904,7 +906,7 @@ namespace TBF.Rig.TestMethods.iPerlCommunication
                                 ///
                                 if (error == CommErr.HeadDisabledByUser || !ckbState[wmNr0])
                                 {
-                                    OnCommCompleted(null, new CommCompletedEventArgs(threadID, wmNr0, ihead, wm, Strings.Opto_head_was_disabled_by_the_user, CommErr.HeadDisabledByUser));
+                                    OnCommCompleted(null, new CommCompletedEventArgs(threadID, wmNr0, ihead, wm, Strings.Head_was_disabled_by_the_user, CommErr.HeadDisabledByUser));
                                 }
 								else if (error == CommErr.None)
 								{
@@ -1892,10 +1894,10 @@ namespace TBF.Rig.TestMethods.iPerlCommunication
         {
             if (ihead.CommFailed) return CommErr.CommFailed;
 
-            if (TBF.Rig.Sequences.ProcessData.IsQ2PreCorrectionCalculated)
+            if (ProcessData.IsQ2PreCorrectionCalculated)
             {
-                return WriteQ2Corrections(threadId, ihead, wm, ref resultStr, TBF.Rig.Sequences.ProcessData.CalculatedQ2PreCorrectionLR,
-                                                                              TBF.Rig.Sequences.ProcessData.CalculatedQ2PreCorrectionRL);
+                return WriteQ2Corrections(threadId, ihead, wm, ref resultStr, ProcessData.CalculatedQ2PreCorrectionLR,
+                                                                              ProcessData.CalculatedQ2PreCorrectionRL);
             }
             else
             {
@@ -1979,10 +1981,10 @@ namespace TBF.Rig.TestMethods.iPerlCommunication
 
             if (wm.Pruefindex == 1)
             {
-                if (TBF.Rig.Sequences.ProcessData.IsQ2PreCorrectionCalculated)
+                if (ProcessData.IsQ2PreCorrectionCalculated)
                 {
-                    return WriteQ2Corrections(threadId, ihead, wm, ref resultStr, TBF.Rig.Sequences.ProcessData.CalculatedQ2PreCorrectionLR,
-                                                                                  TBF.Rig.Sequences.ProcessData.CalculatedQ2PreCorrectionRL);
+                    return WriteQ2Corrections(threadId, ihead, wm, ref resultStr, ProcessData.CalculatedQ2PreCorrectionLR,
+                                                                                  ProcessData.CalculatedQ2PreCorrectionRL);
                 }
                 else
                 {
@@ -2185,9 +2187,7 @@ namespace TBF.Rig.TestMethods.iPerlCommunication
             ///
             if ((q2CorrType == Q2CorrType.Update) || (q2CorrType == Q2CorrType.ConditionalUpdate))
             {
-                ///
                 /// Update or ConditionalUpdate: 1. Calculate updates, not corrections, 2. Use error limits from this test
-                ///
 			    double errLimitLo = test.ErrLimLo + test.Uncertainty;
 			    double errLimitHi = test.ErrLimHi - test.Uncertainty;
 
@@ -2269,9 +2269,7 @@ namespace TBF.Rig.TestMethods.iPerlCommunication
             }
             else
             {
-                ///
                 /// Regular Q2 corrections: 1. Use error limits from 'q2adjResult'
-                ///
                 double errLimitLo = q2adjTestData.ErrLimLo + q2adjTestData.ErrLimMargin;
                 double errLimitHi = q2adjTestData.ErrLimHi - q2adjTestData.ErrLimMargin;
 
@@ -2768,7 +2766,7 @@ namespace TBF.Rig.TestMethods.iPerlCommunication
 				    tstRslt.EndTime     = endTime;
 				    tstRslt.FlowSetTime = 0;
                     tstRslt.MassOfEvapWater = 0;
-                    tstRslt.TestTime   += testTime;             /// [s] total communication time of all tests
+				    tstRslt.TestTime   += testTime;             /// [s] total communication time of all tests
 
 					for (int i = 0; i < iperlHeads.Count; i++)
 					{