Index: DamEngine/trunk/src/Deltares.DamEngine.Calculators/KernelWrappers/MacroStabilityCommon/MacroStabilityIo/InterfaceConversionHelper.cs
===================================================================
diff -u -r6346 -r6350
--- DamEngine/trunk/src/Deltares.DamEngine.Calculators/KernelWrappers/MacroStabilityCommon/MacroStabilityIo/InterfaceConversionHelper.cs	(.../InterfaceConversionHelper.cs)	(revision 6346)
+++ DamEngine/trunk/src/Deltares.DamEngine.Calculators/KernelWrappers/MacroStabilityCommon/MacroStabilityIo/InterfaceConversionHelper.cs	(.../InterfaceConversionHelper.cs)	(revision 6350)
@@ -174,7 +174,10 @@
         return translationTable[damCharacteristicPointType];
     }
     
-    public static SoilType ConvertToMacroStabilitySoil(Data.Geotechnics.Soil soil)
+    /// <summary>Converts to MacroStability soil.</summary>
+    /// <param name="soil">The Dam soil.</param>
+    /// <returns>The MacroStability Soil.</returns>
+    public static SoilType ConvertToMacroStabilitySoil(Soil soil)
     {
         var macroStabilitySoil = new SoilType
         {
@@ -231,6 +234,54 @@
         return macroStabilitySoil;
     }
     
+    /// <summary>Converts to Dam soil.</summary>
+    /// <param name="soil">The MacroStability soil.</param>
+    /// <returns>The Dam soil.</returns>
+    /// <exception cref="System.FormatException"></exception>
+    public static Soil ConvertToDamSoil(SoilType soil)
+    {
+        var damSoil = new Soil
+        {
+            Name = soil.Name,
+            AbovePhreaticLevel = soil.AbovePhreaticLevel,
+            BelowPhreaticLevel = soil.BelowPhreaticLevel,
+            Cohesion = soil.Cohesion,
+            FrictionAngle = soil.FrictionAngle,
+            RatioCuPc = soil.RatioCuPc,
+            StrengthIncreaseExponent = soil.StrengthIncreaseExponent,
+            //Todo #Bka We keep this as "truth" for now. But maybe Dam should become above/below too
+            ShearStrengthModel = ConvertToDamShearStrengthModel(soil.ShearStrengthAbovePhreaticLevelModel)
+        };
+
+        if (soil.SigmaTauTable != null)
+        {
+            damSoil.SigmaTauCurve = new SigmaTauCurve();
+            foreach (SoilTypeSigmaTauTablePoint point in soil.SigmaTauTable)
+            {
+                damSoil.SigmaTauCurve.Points.Add(new SigmaTauPoint
+                {
+                    Sigma = point.Sigma,
+                    Tau = point.Tau
+                });
+            }
+        }
+
+        if (soil.SuTable != null)
+        {
+            damSoil.SuTableCurve = new SuTableCurve();
+            foreach (SoilTypeSuTablePoint point in soil.SuTable)
+            {
+                damSoil.SuTableCurve.Points.Add(new SigmaSuPoint()
+                {
+                    Sigma = point.EffectiveStress,
+                    Su = point.Su
+                });
+            }
+        }
+
+        return damSoil;
+    }
+    
     /// <summary>Converts to macro stability ShearStrengthModel.</summary>
     /// <param name="damShearStrengthModel">The dam ShearStrengthModel.</param>
     /// <returns></returns>
@@ -255,11 +306,34 @@
         return translationTable[damShearStrengthModel];
     }
     
-    /// <summary>Converts to macro stability waterpressure interpolation model.</summary>
-    /// <param name="waterpressureInterpolationModel">The waterpressure interpolation model.</param>
+    /// <summary>Converts to dam ShearStrengthModel.</summary>
+    /// <param name="kernelShearStrengthModel">The kernel ShearStrengthModel.</param>
     /// <returns></returns>
-    public static WaterPressureInterpolationModelType ConvertToMacroStabilityWaterpressureInterpolationModel(WaterpressureInterpolationModel waterpressureInterpolationModel)
+    public static ShearStrengthModel ConvertToDamShearStrengthModel(ShearStrengthModelType kernelShearStrengthModel)
     {
+        var translationTable = new Dictionary<ShearStrengthModelType, ShearStrengthModel>
+        {
+            {
+                ShearStrengthModelType.MohrCoulomb, ShearStrengthModel.CPhi
+            },
+            {
+                ShearStrengthModelType.Shansep, ShearStrengthModel.SuCalculated
+            },
+            {
+                ShearStrengthModelType.SigmaTauTable, ShearStrengthModel.SigmaTauCurve
+            },
+            {
+                ShearStrengthModelType.SuTable, ShearStrengthModel.SuTable
+            }
+        };
+        return translationTable[kernelShearStrengthModel];
+    }
+    
+    /// <summary>Converts to macro stability water pressure interpolation model.</summary>
+    /// <param name="waterPressureInterpolationModel">The water pressure interpolation model.</param>
+    /// <returns></returns>
+    public static WaterPressureInterpolationModelType ConvertToMacroStabilityWaterPressureInterpolationModel(WaterpressureInterpolationModel waterPressureInterpolationModel)
+    {
         var translationTable = new Dictionary<WaterpressureInterpolationModel, WaterPressureInterpolationModelType>
         {
             {
@@ -269,6 +343,6 @@
                 WaterpressureInterpolationModel.Hydrostatic, WaterPressureInterpolationModelType.Hydrostatic
             }
         };
-        return translationTable[waterpressureInterpolationModel];
+        return translationTable[waterPressureInterpolationModel];
     }
 }
\ No newline at end of file
Index: DamEngine/trunk/src/Deltares.DamEngine.Calculators.Tests/KernelWrappers/MacroStabilityCommon/InterfaceConversionHelperTests.cs
===================================================================
diff -u
--- DamEngine/trunk/src/Deltares.DamEngine.Calculators.Tests/KernelWrappers/MacroStabilityCommon/InterfaceConversionHelperTests.cs	(revision 0)
+++ DamEngine/trunk/src/Deltares.DamEngine.Calculators.Tests/KernelWrappers/MacroStabilityCommon/InterfaceConversionHelperTests.cs	(revision 6350)
@@ -0,0 +1,129 @@
+// Copyright (C) Stichting Deltares 2024. All rights reserved.
+// 
+// This file is part of the Dam Engine.
+// 
+// The Dam Engine is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+// 
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Affero General Public License for more details.
+// 
+// You should have received a copy of the GNU Affero General Public License
+// along with this program. If not, see <http://www.gnu.org/licenses/>.
+// 
+// All names, logos, and references to "Deltares" are registered trademarks of
+// Stichting Deltares and remain full property of Stichting Deltares at all times.
+// All rights reserved.
+
+using Deltares.DamEngine.Calculators.KernelWrappers.MacroStabilityCommon.MacroStabilityIo;
+using Deltares.MacroStability.Io.XmlInput;
+using KellermanSoftware.CompareNetObjects;
+using NUnit.Framework;
+
+namespace Deltares.DamEngine.Calculators.Tests.KernelWrappers.MacroStabilityCommon;
+
+[TestFixture]
+public class InterfaceConversionHelperTests
+{
+    [Test]
+    public void GivenMacroStabilitySoilWhenConvertingToDamSoilAndBackThenResultEqualsOriginal()
+    {
+        // Given MacroStability Soil
+        var macroStabilitySoil = new SoilType()
+        {
+            Name = "MacroStabilitySoil",
+            AbovePhreaticLevel = 1.01,
+            BelowPhreaticLevel = 1.02,
+            Cohesion = 1.03,
+            FrictionAngle = 1.04,
+            Dilatancy = 1.04,
+            RatioCuPc = 1.06,
+            ShearStrengthAbovePhreaticLevelModel = ShearStrengthModelType.MohrCoulomb,
+            ShearStrengthBelowPhreaticLevelModel = ShearStrengthModelType.MohrCoulomb,
+            StrengthIncreaseExponent = 1.08,
+            UseSoilClassification = false, // must be false
+            SigmaTauTable = [],
+            SuTable = [],
+            BondStressCurve = null // must be null
+        };
+
+        // When Converting to DamSoil and back
+        Data.Geotechnics.Soil damSoil = InterfaceConversionHelper.ConvertToDamSoil(macroStabilitySoil);
+        SoilType actualMacroStabilitySoil = InterfaceConversionHelper.ConvertToMacroStabilitySoil(damSoil);
+
+        // Then result equals original
+        var compare = new CompareLogic
+        {
+            Config =
+            {
+                MaxDifferences = 100
+            }
+        };
+        ComparisonResult result = compare.Compare(macroStabilitySoil, actualMacroStabilitySoil);
+        Assert.That(result.Differences, Is.Empty, "Differences found converting/reconverting Soil but this ok now if diff = 3");
+    }
+    
+    [Test]
+    public void GivenMacroStabilitySoilWithSuAndSigmaTauTableWhenConvertingToDamSoilAndBackThenResultEqualsOriginal()
+    {
+        // Given MacroStability Soil with filled Su and SigmaTau table
+        var sigmaTauTable = new SoilTypeSigmaTauTablePoint[2];
+        sigmaTauTable[0] = new SoilTypeSigmaTauTablePoint
+        {
+            Sigma = 1.1,
+            Tau = 2.1
+        };
+        sigmaTauTable[1] = new SoilTypeSigmaTauTablePoint
+        {
+            Sigma = 2.1,
+            Tau = 3.1
+        };
+        var suTable = new SoilTypeSuTablePoint[2];
+        suTable[0] = new SoilTypeSuTablePoint
+        {
+            Su = 0.1,
+            EffectiveStress = 10.1
+        };
+        suTable[1] = new SoilTypeSuTablePoint
+        {
+            Su = 1.21,
+            EffectiveStress = 13.4
+        };
+        var macroStabilitySoil = new SoilType()
+        {
+            Name = "MacroStabilitySoil",
+            AbovePhreaticLevel = 1.01,
+            BelowPhreaticLevel = 1.02,
+            Cohesion = 1.03,
+            FrictionAngle = 1.04,
+            Dilatancy = 1.04,
+            RatioCuPc = 1.06,
+            ShearStrengthAbovePhreaticLevelModel = ShearStrengthModelType.MohrCoulomb,
+            ShearStrengthBelowPhreaticLevelModel = ShearStrengthModelType.MohrCoulomb,
+            StrengthIncreaseExponent = 1.08,
+            UseSoilClassification = false, // must be false
+            SigmaTauTable = sigmaTauTable,
+            SuTable = suTable,
+            BondStressCurve = null // must be null
+        };
+
+        // When Converting to DamSoil and back
+        Data.Geotechnics.Soil damSoil = InterfaceConversionHelper.ConvertToDamSoil(macroStabilitySoil);
+        SoilType actualMacroStabilitySoil = InterfaceConversionHelper.ConvertToMacroStabilitySoil(damSoil);
+
+        // Then result equals original
+        var compare = new CompareLogic
+        {
+            Config =
+            {
+                MaxDifferences = 100
+            }
+        };
+        ComparisonResult result = compare.Compare(macroStabilitySoil, actualMacroStabilitySoil);
+        Assert.That(result.Differences, Is.Empty, "Differences found converting/reconverting Soil but this ok now if diff = 3");
+    }
+}
\ No newline at end of file
Index: DamEngine/trunk/src/Deltares.DamEngine.Calculators/KernelWrappers/MacroStabilityCommon/MacroStabilityIo/FillMacroStabilityInterfaceInputFromEngine.cs
===================================================================
diff -u -r6346 -r6350
--- DamEngine/trunk/src/Deltares.DamEngine.Calculators/KernelWrappers/MacroStabilityCommon/MacroStabilityIo/FillMacroStabilityInterfaceInputFromEngine.cs	(.../FillMacroStabilityInterfaceInputFromEngine.cs)	(revision 6346)
+++ DamEngine/trunk/src/Deltares.DamEngine.Calculators/KernelWrappers/MacroStabilityCommon/MacroStabilityIo/FillMacroStabilityInterfaceInputFromEngine.cs	(.../FillMacroStabilityInterfaceInputFromEngine.cs)	(revision 6350)
@@ -458,7 +458,7 @@
                 GeometrySurface = registry.GetId(damSoilLayer2D.GeometrySurface),
                 Soil = registry.GetId(damSoilLayer2D.Soil),
                 WaterPressureInterpolationModelSpecified = true,
-                WaterPressureInterpolationModel = InterfaceConversionHelper.ConvertToMacroStabilityWaterpressureInterpolationModel(damSoilLayer2D
+                WaterPressureInterpolationModel = InterfaceConversionHelper.ConvertToMacroStabilityWaterPressureInterpolationModel(damSoilLayer2D
                                                                                                                                        .WaterpressureInterpolationModel)
             };
             kernelSoilProfile.SoilSurfaces[i] = kernelSoilLayer2D;