diff --git a/src/ZB.MOM.WW.OtOpcUa.Core.Abstractions/DriverDataType.cs b/src/ZB.MOM.WW.OtOpcUa.Core.Abstractions/DriverDataType.cs
index f980d95..b784b0b 100644
--- a/src/ZB.MOM.WW.OtOpcUa.Core.Abstractions/DriverDataType.cs
+++ b/src/ZB.MOM.WW.OtOpcUa.Core.Abstractions/DriverDataType.cs
@@ -25,4 +25,11 @@ public enum DriverDataType
 
     /// <summary>Galaxy-style attribute reference encoded as an OPC UA String.</summary>
     Reference,
+
+    /// <summary>
+    ///     OPC UA <c>Duration</c> — a Double-encoded period in milliseconds. Subtype of Double
+    ///     in the address space; surfaced as <see cref="System.TimeSpan"/> in the driver layer.
+    ///     Used by IEC 61131-3 <c>TIME</c> / <c>TOD</c> attributes (TwinCAT et al.).
+    /// </summary>
+    Duration,
 }
diff --git a/src/ZB.MOM.WW.OtOpcUa.Driver.TwinCAT/AdsTwinCATClient.cs b/src/ZB.MOM.WW.OtOpcUa.Driver.TwinCAT/AdsTwinCATClient.cs
index 5c684c4..2043857 100644
--- a/src/ZB.MOM.WW.OtOpcUa.Driver.TwinCAT/AdsTwinCATClient.cs
+++ b/src/ZB.MOM.WW.OtOpcUa.Driver.TwinCAT/AdsTwinCATClient.cs
@@ -58,6 +58,7 @@ internal sealed class AdsTwinCATClient : ITwinCATClient
             var value = result.Value;
             if (bitIndex is int bit && type == TwinCATDataType.Bool && value is not bool)
                 value = ExtractBit(value, bit);
+            value = PostProcessIecTime(type, value);
 
             return (value, TwinCATStatusMapper.Good);
         }
@@ -143,6 +144,7 @@ internal sealed class AdsTwinCATClient : ITwinCATClient
         var value = args.Value;
         if (reg.BitIndex is int bit && reg.Type == TwinCATDataType.Bool && value is not bool)
             value = ExtractBit(value, bit);
+        value = PostProcessIecTime(reg.Type, value);
         try { reg.OnChange(reg.SymbolPath, value); } catch { /* consumer-side errors don't crash the ADS thread */ }
     }
 
@@ -249,7 +251,7 @@ internal sealed class AdsTwinCATClient : ITwinCATClient
         _ => typeof(int),
     };
 
-    private static object ConvertForWrite(TwinCATDataType type, object? value) => type switch
+    internal static object ConvertForWrite(TwinCATDataType type, object? value) => type switch
     {
         TwinCATDataType.Bool => Convert.ToBoolean(value),
         TwinCATDataType.SInt => Convert.ToSByte(value),
@@ -263,11 +265,79 @@ internal sealed class AdsTwinCATClient : ITwinCATClient
         TwinCATDataType.Real => Convert.ToSingle(value),
         TwinCATDataType.LReal => Convert.ToDouble(value),
         TwinCATDataType.String or TwinCATDataType.WString => Convert.ToString(value) ?? string.Empty,
-        TwinCATDataType.Time or TwinCATDataType.Date
-            or TwinCATDataType.DateTime or TwinCATDataType.TimeOfDay => Convert.ToUInt32(value),
+        // IEC durations (TIME / TOD) accept TimeSpan / Duration-as-Double-ms / raw UDINT.
+        // IEC timestamps (DATE / DT) accept DateTime (UTC) / raw UDINT seconds-since-epoch.
+        TwinCATDataType.Time or TwinCATDataType.TimeOfDay => DurationToUDInt(value),
+        TwinCATDataType.Date or TwinCATDataType.DateTime => DateTimeToUDInt(value),
         _ => throw new NotSupportedException($"TwinCATDataType {type} not writable."),
     };
 
+    // IEC 61131-3 epoch is 1970-01-01 UTC for DATE / DT; TIME / TOD are unsigned ms counters.
+    private static readonly DateTime IecEpochUtc = new(1970, 1, 1, 0, 0, 0, DateTimeKind.Utc);
+
+    /// <summary>
+    ///     Convert the raw UDINT wire value for IEC TIME/DATE/DT/TOD into the native CLR type
+    ///     surfaced upstream — TimeSpan for durations, DateTime (UTC) for timestamps. Other
+    ///     types pass through unchanged.
+    /// </summary>
+    internal static object? PostProcessIecTime(TwinCATDataType type, object? value)
+    {
+        if (value is null) return null;
+        var raw = TryGetUInt32(value);
+        if (raw is null) return value;
+        return type switch
+        {
+            // TIME / TOD — UDINT milliseconds.
+            TwinCATDataType.Time or TwinCATDataType.TimeOfDay
+                => TimeSpan.FromMilliseconds(raw.Value),
+            // DT — UDINT seconds since 1970-01-01 UTC.
+            TwinCATDataType.DateTime
+                => IecEpochUtc.AddSeconds(raw.Value),
+            // DATE — UDINT seconds since 1970-01-01 UTC, but TwinCAT runtimes pin the time
+            // component to midnight; pass through the same conversion so we get a date-only
+            // value at midnight UTC.
+            TwinCATDataType.Date
+                => IecEpochUtc.AddSeconds(raw.Value),
+            _ => value,
+        };
+    }
+
+    private static uint? TryGetUInt32(object value) => value switch
+    {
+        uint u => u,
+        int i when i >= 0 => (uint)i,
+        ushort us => (uint)us,
+        short s when s >= 0 => (uint)s,
+        long l when l >= 0 && l <= uint.MaxValue => (uint)l,
+        ulong ul when ul <= uint.MaxValue => (uint)ul,
+        _ => null,
+    };
+
+    private static uint DurationToUDInt(object? value) => value switch
+    {
+        TimeSpan ts => (uint)Math.Max(0, ts.TotalMilliseconds),
+        // OPC UA Duration on the wire is a Double in milliseconds.
+        double d => (uint)Math.Max(0, d),
+        float f => (uint)Math.Max(0, f),
+        _ => Convert.ToUInt32(value),
+    };
+
+    private static uint DateTimeToUDInt(object? value)
+    {
+        if (value is DateTime dt)
+        {
+            var utc = dt.Kind == DateTimeKind.Unspecified
+                ? DateTime.SpecifyKind(dt, DateTimeKind.Utc)
+                : dt.ToUniversalTime();
+            var seconds = (long)(utc - IecEpochUtc).TotalSeconds;
+            if (seconds < 0 || seconds > uint.MaxValue)
+                throw new ArgumentOutOfRangeException(nameof(value),
+                    "DATE/DT value out of UDINT epoch range (1970-01-01..2106-02-07 UTC).");
+            return (uint)seconds;
+        }
+        return Convert.ToUInt32(value);
+    }
+
     private static bool ExtractBit(object? rawWord, int bit) => rawWord switch
     {
         short s => (s & (1 << bit)) != 0,
diff --git a/src/ZB.MOM.WW.OtOpcUa.Driver.TwinCAT/TwinCATDataType.cs b/src/ZB.MOM.WW.OtOpcUa.Driver.TwinCAT/TwinCATDataType.cs
index d123451..3c25e25 100644
--- a/src/ZB.MOM.WW.OtOpcUa.Driver.TwinCAT/TwinCATDataType.cs
+++ b/src/ZB.MOM.WW.OtOpcUa.Driver.TwinCAT/TwinCATDataType.cs
@@ -42,8 +42,11 @@ public static class TwinCATDataTypeExtensions
         TwinCATDataType.Real => DriverDataType.Float32,
         TwinCATDataType.LReal => DriverDataType.Float64,
         TwinCATDataType.String or TwinCATDataType.WString => DriverDataType.String,
-        TwinCATDataType.Time or TwinCATDataType.Date
-            or TwinCATDataType.DateTime or TwinCATDataType.TimeOfDay => DriverDataType.Int32,
+        // IEC 61131-3 TIME / TOD are durations (ms); DATE / DT are absolute timestamps.
+        // The wire form is UDINT but the driver post-processes into TimeSpan / DateTime so the
+        // address space surfaces native UA Duration / DateTime instead of opaque integers.
+        TwinCATDataType.Time or TwinCATDataType.TimeOfDay => DriverDataType.Duration,
+        TwinCATDataType.Date or TwinCATDataType.DateTime => DriverDataType.DateTime,
         TwinCATDataType.Structure => DriverDataType.String,
         _ => DriverDataType.Int32,
     };
diff --git a/src/ZB.MOM.WW.OtOpcUa.Server/OpcUa/DriverNodeManager.cs b/src/ZB.MOM.WW.OtOpcUa.Server/OpcUa/DriverNodeManager.cs
index b99ad75..e1331a7 100644
--- a/src/ZB.MOM.WW.OtOpcUa.Server/OpcUa/DriverNodeManager.cs
+++ b/src/ZB.MOM.WW.OtOpcUa.Server/OpcUa/DriverNodeManager.cs
@@ -310,6 +310,7 @@ public sealed class DriverNodeManager : CustomNodeManager2, IAddressSpaceBuilder
         DriverDataType.Float64 => DataTypeIds.Double,
         DriverDataType.String => DataTypeIds.String,
         DriverDataType.DateTime => DataTypeIds.DateTime,
+        DriverDataType.Duration => DataTypeIds.Duration,
         _ => DataTypeIds.BaseDataType,
     };
 
diff --git a/tests/ZB.MOM.WW.OtOpcUa.Driver.TwinCAT.Tests/TwinCATDriverTests.cs b/tests/ZB.MOM.WW.OtOpcUa.Driver.TwinCAT.Tests/TwinCATDriverTests.cs
index caa97d1..2bdc2a5 100644
--- a/tests/ZB.MOM.WW.OtOpcUa.Driver.TwinCAT.Tests/TwinCATDriverTests.cs
+++ b/tests/ZB.MOM.WW.OtOpcUa.Driver.TwinCAT.Tests/TwinCATDriverTests.cs
@@ -89,7 +89,91 @@ public sealed class TwinCATDriverTests
         TwinCATDataType.LReal.ToDriverDataType().ShouldBe(DriverDataType.Float64);
         TwinCATDataType.String.ToDriverDataType().ShouldBe(DriverDataType.String);
         TwinCATDataType.WString.ToDriverDataType().ShouldBe(DriverDataType.String);
-        TwinCATDataType.Time.ToDriverDataType().ShouldBe(DriverDataType.Int32);
+        // IEC durations map to UA Duration; absolute timestamps map to UA DateTime.
+        TwinCATDataType.Time.ToDriverDataType().ShouldBe(DriverDataType.Duration);
+        TwinCATDataType.TimeOfDay.ToDriverDataType().ShouldBe(DriverDataType.Duration);
+        TwinCATDataType.Date.ToDriverDataType().ShouldBe(DriverDataType.DateTime);
+        TwinCATDataType.DateTime.ToDriverDataType().ShouldBe(DriverDataType.DateTime);
+    }
+
+    [Fact]
+    public void IecTime_post_process_converts_TIME_to_TimeSpan_ms()
+    {
+        var ts = (TimeSpan)AdsTwinCATClient.PostProcessIecTime(TwinCATDataType.Time, 12_345u)!;
+        ts.ShouldBe(TimeSpan.FromMilliseconds(12_345));
+    }
+
+    [Fact]
+    public void IecTime_post_process_converts_TOD_to_TimeSpan_ms()
+    {
+        var ts = (TimeSpan)AdsTwinCATClient.PostProcessIecTime(TwinCATDataType.TimeOfDay, 3_600_000u)!;
+        ts.ShouldBe(TimeSpan.FromHours(1));
+    }
+
+    [Fact]
+    public void IecTime_post_process_converts_DT_to_DateTime_utc()
+    {
+        // 1970-01-01 + 1 hour = 1970-01-01 01:00:00 UTC
+        var dt = (DateTime)AdsTwinCATClient.PostProcessIecTime(TwinCATDataType.DateTime, 3600u)!;
+        dt.ShouldBe(new DateTime(1970, 1, 1, 1, 0, 0, DateTimeKind.Utc));
+        dt.Kind.ShouldBe(DateTimeKind.Utc);
+    }
+
+    [Fact]
+    public void IecTime_post_process_converts_DATE_to_midnight_utc()
+    {
+        // 86400 seconds = exactly 1970-01-02 00:00 UTC
+        var dt = (DateTime)AdsTwinCATClient.PostProcessIecTime(TwinCATDataType.Date, 86_400u)!;
+        dt.ShouldBe(new DateTime(1970, 1, 2, 0, 0, 0, DateTimeKind.Utc));
+    }
+
+    [Fact]
+    public void IecTime_post_process_passthrough_for_non_time_types()
+    {
+        AdsTwinCATClient.PostProcessIecTime(TwinCATDataType.DInt, 42).ShouldBe(42);
+        AdsTwinCATClient.PostProcessIecTime(TwinCATDataType.LReal, 3.14).ShouldBe(3.14);
+    }
+
+    [Fact]
+    public void ConvertForWrite_TIME_accepts_TimeSpan_and_returns_UDINT_ms()
+    {
+        var raw = AdsTwinCATClient.ConvertForWrite(TwinCATDataType.Time, TimeSpan.FromMilliseconds(2_500));
+        raw.ShouldBeOfType<uint>();
+        ((uint)raw).ShouldBe(2_500u);
+    }
+
+    [Fact]
+    public void ConvertForWrite_TOD_accepts_double_ms()
+    {
+        var raw = AdsTwinCATClient.ConvertForWrite(TwinCATDataType.TimeOfDay, 60_000.0);
+        ((uint)raw).ShouldBe(60_000u);
+    }
+
+    [Fact]
+    public void ConvertForWrite_DT_accepts_DateTime_and_returns_UDINT_seconds()
+    {
+        var raw = AdsTwinCATClient.ConvertForWrite(
+            TwinCATDataType.DateTime,
+            new DateTime(1970, 1, 1, 1, 0, 0, DateTimeKind.Utc));
+        ((uint)raw).ShouldBe(3600u);
+    }
+
+    [Fact]
+    public void ConvertForWrite_DT_round_trips_via_post_process()
+    {
+        var original = new DateTime(2024, 6, 15, 12, 30, 45, DateTimeKind.Utc);
+        var raw = (uint)AdsTwinCATClient.ConvertForWrite(TwinCATDataType.DateTime, original);
+        var roundTrip = (DateTime)AdsTwinCATClient.PostProcessIecTime(TwinCATDataType.DateTime, raw)!;
+        roundTrip.ShouldBe(original);
+    }
+
+    [Fact]
+    public void ConvertForWrite_DT_rejects_pre_epoch_values()
+    {
+        Should.Throw<ArgumentOutOfRangeException>(() =>
+            AdsTwinCATClient.ConvertForWrite(
+                TwinCATDataType.DateTime,
+                new DateTime(1969, 12, 31, 23, 59, 59, DateTimeKind.Utc)));
     }
 
     [Theory]