diff --git a/Common/Hardware/WaterMeter/MechanicalMeter/FM2014/FM2014Core/FM2014.cs b/Common/Hardware/WaterMeter/MechanicalMeter/FM2014/FM2014Core/FM2014.cs
index b6969c17..ffe42737 100644
--- a/Common/Hardware/WaterMeter/MechanicalMeter/FM2014/FM2014Core/FM2014.cs
+++ b/Common/Hardware/WaterMeter/MechanicalMeter/FM2014/FM2014Core/FM2014.cs
@@ -1131,7 +1131,6 @@ namespace Sensus.Common.Hardware.WaterMeter.MechanicalMeter.FM2014.FM2014Core
         private Boolean Read(CmdName cmdName, out String responseStr)
         {
             responseStr = "";
-            var cmdCodeStr = GetCmdStr(cmdName);
             var info = $"{Resources.StrCommResponse}: {GetCmdInfo(cmdName)}";
             var statusReturn = StatusReturn.Failed;
 
diff --git a/MiniPrf/Ui/FrmMainMiniPrf.Designer.cs b/MiniPrf/Ui/FrmMainMiniPrf.Designer.cs
index 3c01eb49..5039cd5d 100644
--- a/MiniPrf/Ui/FrmMainMiniPrf.Designer.cs
+++ b/MiniPrf/Ui/FrmMainMiniPrf.Designer.cs
@@ -316,6 +316,7 @@
             this.cbxAttenuation.TabIndex = 6;
             this.cbxAttenuation.Text = "3";
             this.cbxAttenuation.SelectedIndexChanged += new System.EventHandler(this.cbxAttenuation_SelectedIndexChanged);
+            this.cbxAttenuation.KeyDown += new System.Windows.Forms.KeyEventHandler(this.cbxAttenuation_KeyDown);
             // 
             // lblRefPulsePerVolume
             // 
diff --git a/MiniPrf/Ui/FrmMainMiniPrf.cs b/MiniPrf/Ui/FrmMainMiniPrf.cs
index cb204144..58553179 100644
--- a/MiniPrf/Ui/FrmMainMiniPrf.cs
+++ b/MiniPrf/Ui/FrmMainMiniPrf.cs
@@ -42,6 +42,8 @@ using System.IO;
 using System.IO.Ports;
 using System.Linq;
 using System.Reflection;
+using System.Text.RegularExpressions;
+using System.Threading;
 using System.Threading.Tasks;
 using System.Windows.Forms;
 using Sensus.Common.Hardware.WaterMeter.MechanicalMeter.FM2014.FM2014Core.Consts;
@@ -582,16 +584,18 @@ namespace Sensus.MiniPrf.Ui
             tbxScaleRefToDut.Text = $@"{Fm2014.RefToDutScale_norm:F4}";
 
             // Display error if scale doesn't fit
-            if (Math.Abs(Fm2014.RefToDutScale_norm -
-                (Single)Fm2014.Ref_pulse_per_cm / Fm2014.Dut_pulse_per_cm) > FM2014.RefToDutScaleMin ||
+            var tempRefToDutScale_norm = (Double)Fm2014.Ref_pulse_per_cm / Fm2014.Dut_pulse_per_cm;
+            if (tempRefToDutScale_norm < FM2014.RefToDutScaleMin ||
+                tempRefToDutScale_norm > FM2014.RefToDutScaleMax ||
                 Fm2014.RefToDutScale_norm < FM2014.RefToDutScaleMin ||
                 Fm2014.RefToDutScale_norm > FM2014.RefToDutScaleMax)
-            {
+            { 
                 tbxScaleRefToDut.BackColor = ColorProcessFailed;
                 tbxScaleRefToDut.Text = Resources.StrError;
                 btnSaveRegulationSetup.Enabled = false;
                 return false;
             }
+
             return true;
         }
 
@@ -853,14 +857,35 @@ namespace Sensus.MiniPrf.Ui
         /// </summary>
         /// <param name="sender"></param>
         /// <param name="e"></param>
-        /// <remarks date="2023-Jan-14..18" author="Thomas Wiedebusch">
+        /// <remarks date="2023-Jan-14..24" author="Thomas Wiedebusch">
         /// - Initial.
         /// </remarks>
         private void tbxRefPulsesPerCm_KeyDown(Object sender, KeyEventArgs e)
         {
+            // Catch the enter key, recalculate all settings
             if (e.KeyCode == Keys.Enter)
             {
                 tbxRefPulsesPerCm_Leave(this, null);
+                SelectNextControl(ActiveControl, true, true, true, true);
+            }
+
+            else if (e.KeyCode != Keys.Back && 
+                     e.KeyCode != Keys.Left &&
+                     e.KeyCode != Keys.Right &&
+                     !Regex.IsMatch($"{e.KeyCode}", @"[0-9]"))
+            {
+                e.SuppressKeyPress = true;
+            }
+            else
+            {
+                // Take the new input and calculate the results after the input has been taken after this event!
+                Task.Factory.StartNew(() =>
+                {
+                    Thread.Sleep(1);
+                }).ContinueWith(delegate
+                {
+                    tbxRefPulsesPerCm_Leave(this, null);
+                });
             }
         }
 
@@ -869,157 +894,35 @@ namespace Sensus.MiniPrf.Ui
         /// </summary>
         /// <param name="sender"></param>
         /// <param name="e"></param>
-        /// <remarks date="2023-Jan-14..20" author="Thomas Wiedebusch">
+        /// <remarks date="2023-Jan-14..24" author="Thomas Wiedebusch">
         /// - Initial.
         /// </remarks>
         private void tbxRefPulsesPerCm_Leave(Object sender, EventArgs e)
         {
-            // Setup FM2014
-            if (Fm2014 != null && int.TryParse(tbxRefPulsePerCm.Text, out var pulses_per_cm))
+            Invoke(new Action(() =>
             {
-                //Backup the actual setting to detect changes
-                var backupPulses_per_cm = Fm2014.Ref_pulse_per_cm;
-
-                Fm2014.Ref_pulse_per_cm = (UInt32)pulses_per_cm;
-                // Output the Fm2014 setting to avoid wrong display of invalid ranges as this will be
-                // limited during the setup of the FM2014 property!
-                tbxRefPulsePerCm.Text = $@"{Fm2014.Ref_pulse_per_cm:D}";
-                // During setup of the 'Ref_pulse_per_cm' the 'RefToDutScaleStr' will be generated
-                if (!UpdateRefToDutScale())
-                {
-                    tbxRefPulsePerCm.BackColor = ColorProcessFailed;
+                if (Fm2014 == null) 
                     return;
-                }
-                // Check if values have changed and need to be updated in the standalone setup
-                if (backupPulses_per_cm != Fm2014.Ref_pulse_per_cm)
+
+                if (string.IsNullOrEmpty(tbxRefPulsePerCm.Text))
                 {
-                    SetupHasChanged();
-                }
-
-                // SPECIAL BACKUP AND RESTORE FOR REF CALIBRATION
-
-                // If the REF pulses per cubic meter have been changed manually, the 'Manual REF Calibration'
-                // fields have to be cleared if those are different. A backup to restore it may be useful.
-                if (!tbxRefPulsePerCm.Text.Equals(tbxRefCalibrationResultPulsePerCm.Text) &&
-                    !string.IsNullOrEmpty(tbxRefCalibrationResultPulsePerCm.Text))
-                {
-                    _backupMeasuredRefPulsesStr = tbxMeasuredRefPulses.Text;
-                    tbxMeasuredRefPulses.Text = "";
-                    _backupRefCalibrationResultPulsePerCmStr = tbxRefCalibrationResultPulsePerCm.Text;
-                    tbxRefCalibrationResultPulsePerCm.Text = "";
-                    _backupWeightScaleVolumeLitersStr = tbxManualInputVolumeLiters.Text;
-                    tbxManualInputVolumeLiters.Text = "";
-                }
-                // Restore values if REF pulses per cubic meters is back to the calibrated one
-                else if (tbxRefPulsePerCm.Text.Equals(_backupRefCalibrationResultPulsePerCmStr))
-                {
-                    tbxMeasuredRefPulses.Text = _backupMeasuredRefPulsesStr;
-                    tbxRefCalibrationResultPulsePerCm.Text = _backupRefCalibrationResultPulsePerCmStr;
-                    tbxManualInputVolumeLiters.Text = _backupWeightScaleVolumeLitersStr;
-                }
-            }
-        }
-        /// <summary>
-        /// Redirect keystroke 'Enter' to leaving the cell event
-        /// </summary>
-        /// <param name="sender"></param>
-        /// <param name="e"></param>
-        /// <remarks date="2023-Jan-14" author="Thomas Wiedebusch">
-        /// - Initial.
-        /// </remarks>
-        private void tbxDutPulsesPerCm_KeyDown(Object sender, KeyEventArgs e)
-        {
-            if (e.KeyCode == Keys.Enter)
-            {
-                tbxDutPulsesPerCm_Leave(this, null);
-            }
-        }
-        /// <summary>
-        /// After manual input of the DUT pulses per cubic meter the scale REF to DUT has to be recalculated
-        /// </summary>
-        /// <param name="sender"></param>
-        /// <param name="e"></param>
-        /// <remarks date="2023-Jan-14..20" author="Thomas Wiedebusch">
-        /// - Initial.
-        /// </remarks>
-        private void tbxDutPulsesPerCm_Leave(Object sender, EventArgs e)
-        {
-            // Setup FM2014
-            if (Fm2014 != null && int.TryParse(tbxDutPulsePerCm.Text, out var pulses_per_cm))
-            {
-                //Backup the actual setting to detect changes
-                var backupPulses_per_cm = Fm2014.Dut_pulse_per_cm;
-                // Try to set the new calculated REF pulses limited by the property setter
-                Fm2014.Dut_pulse_per_cm = (UInt32)pulses_per_cm;
-                // Output the Fm2014 setting to avoid wrong display of invalid ranges as this will be
-                // limited during the setup of the FM2014 property!
-                tbxDutPulsePerCm.Text = $@"{Fm2014.Dut_pulse_per_cm:D}";
-                // During setup of the 'Dut_pulse_per_cm' the 'RefToDutScaleStr' will be generated
-                if (!UpdateRefToDutScale())
-                {
-                    tbxDutPulsePerCm.BackColor = ColorProcessFailed;
-                    return;
-                }
-
-                // Check if values have changed and need to be updated in the standalone setup
-                if (backupPulses_per_cm != Fm2014.Dut_pulse_per_cm)
-                {
-                    SetupHasChanged();
-                }
-            }
-        }
-
-        /// <summary>
-        /// Redirect keystroke 'Enter' to leaving the cell event
-        /// </summary>
-        /// <param name="sender"></param>
-        /// <param name="e"></param>
-        /// <remarks date="2023-Jan-15" author="Thomas Wiedebusch">
-        /// - Initial.
-        /// </remarks>
-        private void tbxManualInputVolumeLiters_KeyStoke(Object sender, KeyEventArgs e)
-        {
-            if (e.KeyCode == Keys.Enter)
-            {
-                tbxManualInputVolumeLiters_Leave(this, null);
-            }
-        }
-        /// <summary>
-        /// After manual input of measured weight scale or reservoir in liters this will calculate the
-        /// REF pulses per cubic meter and copy from REF pulses per cubic meter in 'Manual REF Calibration'
-        /// to 'Regulation Setup'.
-        /// </summary>
-        /// <param name="sender"></param>
-        /// <param name="e"></param>
-        /// <remarks date="2023-Jan-15..20" author="Thomas Wiedebusch">
-        /// - Initial.
-        /// </remarks>
-        private void tbxManualInputVolumeLiters_Leave(Object sender, EventArgs e)
-        {
-            // Calculate REF pulses per cubic meter
-            if (int.TryParse(tbxMeasuredRefPulses.Text, out var pulses) && pulses > 0 &&
-                int.TryParse(tbxManualInputVolumeLiters.Text, out var liters) && liters > 0)
-            {
-                //Backup the actual setting to detect changes
-                var backupPulses_per_cm = Fm2014.Ref_pulse_per_cm;
-
-                // Calculate the new pulse ratio based on the manual calibration
-                var pulses_per_cm = (UInt16)(pulses / (liters / 1000.0f));
-
-                // Try to set the new calculated REF pulses limited by the property setter
-                Fm2014.Ref_pulse_per_cm = pulses_per_cm;
-
-                // If this succeeded, then update the new manual calibrated value
-                if (pulses_per_cm == Fm2014.Ref_pulse_per_cm)
-                {
-                    tbxRefCalibrationResultPulsePerCm.Text = $@"{Fm2014.Ref_pulse_per_cm:D}";
                     tbxRefPulsePerCm.Text = $@"{Fm2014.Ref_pulse_per_cm:D}";
-                    tbxManualInputVolumeLiters.BackColor = ColorStandardInputField;
-                    tbxRefCalibrationResultPulsePerCm.BackColor = ColorStandardDisplayField;
+                }
 
+                // Setup FM2014
+                if (int.TryParse(tbxRefPulsePerCm.Text, out var pulses_per_cm))
+                {
+                    //Backup the actual setting to detect changes
+                    var backupPulses_per_cm = Fm2014.Ref_pulse_per_cm;
+
+                    Fm2014.Ref_pulse_per_cm = (UInt32)pulses_per_cm;
+                    // Output the Fm2014 setting to avoid wrong display of invalid ranges as this will be
+                    // limited during the setup of the FM2014 property!
+                    tbxRefPulsePerCm.Text = $@"{Fm2014.Ref_pulse_per_cm:D}";
+                    // During setup of the 'Ref_pulse_per_cm' the 'RefToDutScaleStr' will be generated
                     if (!UpdateRefToDutScale())
                     {
-                        tbxManualInputVolumeLiters.BackColor = ColorProcessFailed;
+                        tbxRefPulsePerCm.BackColor = ColorProcessFailed;
                         return;
                     }
 
@@ -1028,14 +931,213 @@ namespace Sensus.MiniPrf.Ui
                     {
                         SetupHasChanged();
                     }
+
+                    // SPECIAL BACKUP AND RESTORE FOR REF CALIBRATION
+
+                    // If the REF pulses per cubic meter have been changed manually, the 'Manual REF Calibration'
+                    // fields have to be cleared if those are different. A backup to restore it may be useful.
+                    if (!tbxRefPulsePerCm.Text.Equals(tbxRefCalibrationResultPulsePerCm.Text) &&
+                        !string.IsNullOrEmpty(tbxRefCalibrationResultPulsePerCm.Text))
+                    {
+                        _backupMeasuredRefPulsesStr = tbxMeasuredRefPulses.Text;
+                        tbxMeasuredRefPulses.Text = "";
+                        _backupRefCalibrationResultPulsePerCmStr = tbxRefCalibrationResultPulsePerCm.Text;
+                        tbxRefCalibrationResultPulsePerCm.Text = "";
+                        _backupWeightScaleVolumeLitersStr = tbxManualInputVolumeLiters.Text;
+                        tbxManualInputVolumeLiters.Text = "";
+                    }
+                    // Restore values if REF pulses per cubic meters is back to the calibrated one
+                    else if (tbxRefPulsePerCm.Text.Equals(_backupRefCalibrationResultPulsePerCmStr))
+                    {
+                        tbxMeasuredRefPulses.Text = _backupMeasuredRefPulsesStr;
+                        tbxRefCalibrationResultPulsePerCm.Text = _backupRefCalibrationResultPulsePerCmStr;
+                        tbxManualInputVolumeLiters.Text = _backupWeightScaleVolumeLitersStr;
+                    }
                 }
-                else
-                {
-                    tbxManualInputVolumeLiters.BackColor = ColorProcessFailed;
-                    tbxRefCalibrationResultPulsePerCm.BackColor = ColorProcessFailed;
-                    tbxRefCalibrationResultPulsePerCm.Text = Resources.StrError;
-                }
+            }));
+        }
+        /// <summary>
+        /// Redirect keystroke 'Enter' to leaving the cell event
+        /// </summary>
+        /// <param name="sender"></param>
+        /// <param name="e"></param>
+        /// <remarks date="2023-Jan-14..24" author="Thomas Wiedebusch">
+        /// - Initial.
+        /// </remarks>
+        private void tbxDutPulsesPerCm_KeyDown(Object sender, KeyEventArgs e)
+        {
+            // Catch the enter key, recalculate all settings
+            if (e.KeyCode == Keys.Enter)
+            {
+                tbxDutPulsesPerCm_Leave(this, null);
+                SelectNextControl(ActiveControl, true, true, true, true);
             }
+
+            else if (e.KeyCode != Keys.Back && 
+                     e.KeyCode != Keys.Left &&
+                     e.KeyCode != Keys.Right &&
+                     !Regex.IsMatch($"{e.KeyCode}", @"[0-9]"))
+            {
+                e.SuppressKeyPress = true;
+            }
+            else
+            {
+                // Take the new input and calculate the results after the input has been taken after this event!
+                Task.Factory.StartNew(() =>
+                {
+                    Thread.Sleep(1);
+                }).ContinueWith(delegate
+                {
+                    tbxDutPulsesPerCm_Leave(this, null);
+                });
+            }
+        }
+
+        /// <summary>
+        /// After manual input of the DUT pulses per cubic meter the scale REF to DUT has to be recalculated
+        /// </summary>
+        /// <param name="sender"></param>
+        /// <param name="e"></param>
+        /// <remarks date="2023-Jan-14..24" author="Thomas Wiedebusch">
+        /// - Initial.
+        /// </remarks>
+        private void tbxDutPulsesPerCm_Leave(Object sender, EventArgs e)
+        {
+            Invoke(new Action(() =>
+            {
+                if (Fm2014 == null) 
+                    return;
+
+                if (string.IsNullOrEmpty(tbxDutPulsePerCm.Text))
+                {
+                    tbxDutPulsePerCm.Text = $@"{Fm2014.Dut_pulse_per_cm:D}";
+                }
+                // Setup FM2014
+                if (int.TryParse(tbxDutPulsePerCm.Text, out var pulses_per_cm))
+                {
+                    //Backup the actual setting to detect changes
+                    var backupPulses_per_cm = Fm2014.Dut_pulse_per_cm;
+                    // Try to set the new calculated REF pulses limited by the property setter
+                    Fm2014.Dut_pulse_per_cm = (UInt32)pulses_per_cm;
+                    // Output the Fm2014 setting to avoid wrong display of invalid ranges as this will be
+                    // limited during the setup of the FM2014 property!
+                    tbxDutPulsePerCm.Text = $@"{Fm2014.Dut_pulse_per_cm:D}";
+                    // During setup of the 'Dut_pulse_per_cm' the 'RefToDutScaleStr' will be generated
+                    if (!UpdateRefToDutScale())
+                    {
+                        tbxDutPulsePerCm.BackColor = ColorProcessFailed;
+                        return;
+                    }
+
+                    // Check if values have changed and need to be updated in the standalone setup
+                    if (backupPulses_per_cm != Fm2014.Dut_pulse_per_cm)
+                    {
+                        SetupHasChanged();
+                    }
+                }
+            }));
+        }
+
+        /// <summary>
+        /// Redirect keystroke 'Enter' to leaving the cell event
+        /// </summary>
+        /// <param name="sender"></param>
+        /// <param name="e"></param>
+        /// <remarks date="2023-Jan-15..24" author="Thomas Wiedebusch">
+        /// - Initial.
+        /// </remarks>
+        private void tbxManualInputVolumeLiters_KeyStoke(Object sender, KeyEventArgs e)
+        {
+            // Catch the enter key, recalculate all settings
+            if (e.KeyCode == Keys.Enter)
+            {
+                tbxManualInputVolumeLiters_Leave(this, null);
+                SelectNextControl(ActiveControl, true, true, true, true);
+            }
+
+            else if (e.KeyCode != Keys.Back && 
+                     e.KeyCode != Keys.Left &&
+                     e.KeyCode != Keys.Right &&
+                     !Regex.IsMatch($"{e.KeyCode}", @"[0-9]"))
+            {
+                e.SuppressKeyPress = true;
+            }
+            else
+            {
+                // Take the new input and calculate the results after the input has been taken after this event!
+                Task.Factory.StartNew(() =>
+                {
+                    Thread.Sleep(1);
+                }).ContinueWith(delegate
+                {
+                    tbxManualInputVolumeLiters_Leave(this, null);
+                });
+            }
+        }
+
+        /// <summary>
+        /// After manual input of measured weight scale or reservoir in liters this will calculate the
+        /// REF pulses per cubic meter and copy from REF pulses per cubic meter in 'Manual REF Calibration'
+        /// to 'Regulation Setup'.
+        /// </summary>
+        /// <param name="sender"></param>
+        /// <param name="e"></param>
+        /// <remarks date="2023-Jan-15..24" author="Thomas Wiedebusch">
+        /// - Initial.
+        /// </remarks>
+        private void tbxManualInputVolumeLiters_Leave(Object sender, EventArgs e)
+        {
+            Invoke(new Action(() =>
+            {
+                if (Fm2014 == null) 
+                    return;
+
+                if (string.IsNullOrEmpty(tbxRefPulsePerCm.Text))
+                {
+                    tbxManualInputVolumeLiters.Text = @"0";
+                }
+                // Calculate REF pulses per cubic meter
+                if (int.TryParse(tbxMeasuredRefPulses.Text, out var pulses) && pulses > 0 &&
+                    int.TryParse(tbxManualInputVolumeLiters.Text, out var liters) && liters > 0)
+                {
+                    //Backup the actual setting to detect changes
+                    var backupPulses_per_cm = Fm2014.Ref_pulse_per_cm;
+
+                    // Calculate the new pulse ratio based on the manual calibration
+                    var pulses_per_cm = (UInt16)(pulses / (liters / 1000.0f));
+
+                    // Try to set the new calculated REF pulses limited by the property setter
+                    Fm2014.Ref_pulse_per_cm = pulses_per_cm;
+
+                    // If this succeeded, then update the new manual calibrated value
+                    if (pulses_per_cm == Fm2014.Ref_pulse_per_cm)
+                    {
+                        tbxRefCalibrationResultPulsePerCm.Text = $@"{Fm2014.Ref_pulse_per_cm:D}";
+                        tbxRefPulsePerCm.Text = $@"{Fm2014.Ref_pulse_per_cm:D}";
+                        tbxManualInputVolumeLiters.BackColor = ColorStandardInputField;
+                        tbxRefCalibrationResultPulsePerCm.BackColor = ColorStandardDisplayField;
+
+                        if (!UpdateRefToDutScale())
+                        {
+                            tbxManualInputVolumeLiters.BackColor = ColorProcessFailed;
+                            return;
+                        }
+
+                        // Check if values have changed and need to be updated in the standalone setup
+                        if (backupPulses_per_cm != Fm2014.Ref_pulse_per_cm)
+                        {
+                            SetupHasChanged();
+                        }
+                    }
+                    else
+                    {
+                        tbxManualInputVolumeLiters.BackColor = ColorProcessFailed;
+                        tbxRefCalibrationResultPulsePerCm.BackColor = ColorProcessFailed;
+                        tbxRefCalibrationResultPulsePerCm.Text = Resources.StrError;
+                    }
+                }
+            }));
+
         }
 
         /// <summary>
@@ -1054,6 +1156,19 @@ namespace Sensus.MiniPrf.Ui
 
         }
 
+        /// <summary>
+        /// Select next control on enter key pressed
+        /// </summary>
+        /// <param name="sender"></param>
+        /// <param name="e"></param>
+        private void cbxAttenuation_KeyDown(Object sender, KeyEventArgs e)
+        {
+            if (e.KeyCode == Keys.Enter)
+            {
+                SelectNextControl(ActiveControl, true, true, true, true);
+            }
+        }
+
         #endregion Buttons and Controls
 
         #region Event handler
@@ -1178,5 +1293,6 @@ namespace Sensus.MiniPrf.Ui
 
         }
         #endregion
+
     }
 }