diff --git a/docs/drivers/AbCip.md b/docs/drivers/AbCip.md
index ff97cbb4..d3c6e69b 100644
--- a/docs/drivers/AbCip.md
+++ b/docs/drivers/AbCip.md
@@ -76,7 +76,7 @@ the driver's `DriverConfig` JSON. Key fields:
 - **`Devices`** — one `AbCipDeviceOptions` per PLC (`HostAddress`, `PlcFamily`, optional `DeviceName`, per-device `AllowPacking` / `ConnectionSize` overrides).
 - **`Tags`** — pre-declared `AbCipTagDefinition` list; `Members` for UDT fan-out, `SafetyTag` for GuardLogix safety-partition tags.
 - **`Probe`** — connectivity-probe `Enabled` / `Interval` / `Timeout` / `ProbeTagPath`. A driver created from the AdminUI starts with the probe **off** (an enabled probe with no tag path only logs a warning); an absent `probe` key in a stored config still means enabled to the driver.
-- AdminUI driver forms (AbCip/AbLegacy) overlay only the keys they edit onto the stored JSON, so unmodelled keys survive a save (#576).
+- AdminUI driver forms (AbCip/AbLegacy) overlay only the keys they edit onto the stored JSON, so unmodelled keys survive a save (#576). They also write durations as the integer-millisecond keys the factory binds (`timeoutMs`, `alarmPollIntervalMs`, `probe.intervalMs`, `probe.timeoutMs`); a legacy TimeSpan-string key (`timeout`: "00:00:05") is loaded and migrated on save.
 - **`Transport`** — absent (default ⇒ `Native`), `Native`, or `Libplctag` (fallback); see [Transport](#transport-transport-option).
 - **Discovery** — `EnableControllerBrowse` (`@tags` walk) and `EnableDeclarationOnlyUdtGrouping` (whole-UDT read fast path).
 - **Alarms** — `EnableAlarmProjection` + `AlarmPollInterval` for the ALMD projection.
diff --git a/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbCip/ZB.MOM.WW.OtOpcUa.Driver.AbCip.csproj b/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbCip/ZB.MOM.WW.OtOpcUa.Driver.AbCip.csproj
index 59436b5e..8a42ca70 100644
--- a/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbCip/ZB.MOM.WW.OtOpcUa.Driver.AbCip.csproj
+++ b/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbCip/ZB.MOM.WW.OtOpcUa.Driver.AbCip.csproj
@@ -28,6 +28,7 @@
 
     <ItemGroup>
         <InternalsVisibleTo Include="ZB.MOM.WW.OtOpcUa.Driver.AbCip.Tests"/>
+        <InternalsVisibleTo Include="ZB.MOM.WW.OtOpcUa.AdminUI.Tests"/>
         <InternalsVisibleTo Include="ZB.MOM.WW.OtOpcUa.Driver.AbCip.IntegrationTests"/>
     </ItemGroup>
 
diff --git a/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.csproj b/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.csproj
index b4fe82f3..fa98205f 100644
--- a/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.csproj
+++ b/src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.csproj
@@ -28,6 +28,7 @@
 
     <ItemGroup>
         <InternalsVisibleTo Include="ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.Tests"/>
+        <InternalsVisibleTo Include="ZB.MOM.WW.OtOpcUa.AdminUI.Tests"/>
     </ItemGroup>
 
 </Project>
diff --git a/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Shared/Drivers/DriverConfigJsonOverlay.cs b/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Shared/Drivers/DriverConfigJsonOverlay.cs
index 09901ccd..ddc10468 100644
--- a/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Shared/Drivers/DriverConfigJsonOverlay.cs
+++ b/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Shared/Drivers/DriverConfigJsonOverlay.cs
@@ -16,15 +16,37 @@ internal static class DriverConfigJsonOverlay
     /// <param name="originalJson">The stored config as loaded; blank or non-object input yields <paramref name="typedJson"/> unchanged.</param>
     /// <param name="typedJson">The form's own serialised options.</param>
     /// <param name="ownedPaths">Dot-separated, case-insensitive property paths the form edits (e.g. <c>transport</c>, <c>probe.enabled</c>).</param>
-    public static string Apply(string? originalJson, string typedJson, IEnumerable<string> ownedPaths)
+    /// <param name="timeSpanToMs">
+    ///     (TimeSpan-string path, integer-millisecond path) pairs. The typed options serialise durations as
+    ///     <c>"00:00:05"</c> but the driver factories bind <c>*Ms</c> integers (#576); each pair is rewritten
+    ///     in the typed output (and the legacy TimeSpan path becomes owned, so a stale one is removed).
+    /// </param>
+    public static string Apply(string? originalJson, string typedJson, IEnumerable<string> ownedPaths,
+        IReadOnlyList<(string TimeSpanPath, string MsPath)>? timeSpanToMs = null)
     {
-        if (string.IsNullOrWhiteSpace(originalJson)) return typedJson;
-        JsonObject? original;
-        try { original = JsonNode.Parse(originalJson) as JsonObject; }
-        catch (JsonException) { return typedJson; }
-        if (original is null || JsonNode.Parse(typedJson) is not JsonObject typed) return typedJson;
+        if (JsonNode.Parse(typedJson) is not JsonObject typed) return typedJson;
+        var owned = ownedPaths.ToList();
+        foreach (var (tsPath, msPath) in timeSpanToMs ?? [])
+        {
+            owned.Add(tsPath);
+            owned.Add(msPath);
+            if (Get(typed, tsPath) is JsonValue v && v.TryGetValue<string>(out var text)
+                && TimeSpan.TryParse(text, System.Globalization.CultureInfo.InvariantCulture, out var ts))
+            {
+                RemovePath(typed, tsPath);
+                Set(typed, msPath, (int)ts.TotalMilliseconds);
+            }
+        }
 
-        foreach (var path in ownedPaths)
+        JsonObject? original = null;
+        if (!string.IsNullOrWhiteSpace(originalJson))
+        {
+            try { original = JsonNode.Parse(originalJson) as JsonObject; }
+            catch (JsonException) { /* unusable original: fall through to the typed output */ }
+        }
+        if (original is null) return typed.ToJsonString();
+
+        foreach (var path in owned)
         {
             var segments = path.Split('.');
             JsonObject? from = typed;
@@ -50,6 +72,35 @@ internal static class DriverConfigJsonOverlay
         return original.ToJsonString();
     }
 
+    private static JsonNode? Get(JsonObject root, string path)
+    {
+        JsonNode? cur = root;
+        foreach (var seg in path.Split('.'))
+            cur = cur is JsonObject o ? Find(o, seg) : null;
+        return cur;
+    }
+
+    private static void RemovePath(JsonObject root, string path)
+    {
+        var segs = path.Split('.');
+        JsonObject? cur = root;
+        for (var i = 0; i < segs.Length - 1 && cur is not null; i++)
+            cur = Find(cur, segs[i]) as JsonObject;
+        if (cur is not null) Remove(cur, segs[^1]);
+    }
+
+    private static void Set(JsonObject root, string path, JsonNode value)
+    {
+        var segs = path.Split('.');
+        var cur = root;
+        for (var i = 0; i < segs.Length - 1; i++)
+        {
+            if (Find(cur, segs[i]) is not JsonObject next) { next = []; cur[segs[i]] = next; }
+            cur = next;
+        }
+        cur[segs[^1]] = value;
+    }
+
     private static JsonNode? Find(JsonObject o, string key)
     {
         foreach (var kv in o)
diff --git a/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Shared/Drivers/DriverConfigMs.cs b/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Shared/Drivers/DriverConfigMs.cs
new file mode 100644
index 00000000..34250323
--- /dev/null
+++ b/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Shared/Drivers/DriverConfigMs.cs
@@ -0,0 +1,39 @@
+using System.Text.Json;
+using System.Text.Json.Nodes;
+
+namespace ZB.MOM.WW.OtOpcUa.AdminUI.Components.Shared.Drivers;
+
+/// <summary>
+///     Shared millisecond helpers for the AB forms (#576): the driver factories bind <c>*Ms</c> integers
+///     while the forms edit whole seconds, so a sub-second stored value must survive an edit of an
+///     unrelated field.
+/// </summary>
+internal static class DriverConfigMs
+{
+    /// <summary>Reads an integer-millisecond key at <paramref name="path"/> from <paramref name="json"/>, or null.</summary>
+    public static int? Read(string? json, string path)
+    {
+        if (string.IsNullOrWhiteSpace(json)) return null;
+        try
+        {
+            JsonNode? cur = JsonNode.Parse(json);
+            foreach (var seg in path.Split('.'))
+            {
+                if (cur is not JsonObject o) return null;
+                cur = o.FirstOrDefault(kv => string.Equals(kv.Key, seg, StringComparison.OrdinalIgnoreCase)).Value;
+            }
+            return cur is JsonValue v && v.TryGetValue<int>(out var ms) ? ms : null;
+        }
+        catch (JsonException) { return null; }
+    }
+
+    /// <summary>Whole seconds for display (truncating, like the pre-#576 forms).</summary>
+    public static int ToSeconds(TimeSpan t) => (int)t.TotalSeconds;
+
+    /// <summary>
+    ///     The duration to save: the loaded value when the operator left the seconds field unchanged
+    ///     (keeps 500 ms from collapsing to 0 s), else the edited whole seconds.
+    /// </summary>
+    public static TimeSpan Save(int seconds, TimeSpan? loaded)
+        => loaded is { } l && ToSeconds(l) == seconds ? l : TimeSpan.FromSeconds(seconds);
+}
diff --git a/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Shared/Drivers/Forms/AbCipDriverForm.razor b/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Shared/Drivers/Forms/AbCipDriverForm.razor
index e3e765c7..093822d8 100644
--- a/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Shared/Drivers/Forms/AbCipDriverForm.razor
+++ b/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Shared/Drivers/Forms/AbCipDriverForm.razor
@@ -139,9 +139,16 @@
     /// <summary>Top-level/nested JSON paths this form edits; everything else in the stored config is preserved.</summary>
     internal static readonly string[] OwnedPaths =
     [
-        "timeout", "transport", "enableControllerBrowse", "enableDeclarationOnlyUdtGrouping",
-        "enableAlarmProjection", "alarmPollInterval", "maxConcurrentReads", "probeTimeoutSeconds",
-        "probe.enabled", "probe.interval", "probe.timeout", "probe.probeTagPath",
+        "transport", "enableControllerBrowse", "enableDeclarationOnlyUdtGrouping",
+        "enableAlarmProjection", "maxConcurrentReads", "probeTimeoutSeconds",
+        "probe.enabled", "probe.probeTagPath",
+    ];
+
+    /// <summary>The factory binds integer-millisecond keys, not the TimeSpan strings the typed options serialise (#576).</summary>
+    internal static readonly (string TimeSpanPath, string MsPath)[] TimeSpanToMs =
+    [
+        ("timeout", "timeoutMs"), ("alarmPollInterval", "alarmPollIntervalMs"),
+        ("probe.interval", "probe.intervalMs"), ("probe.timeout", "probe.timeoutMs"),
     ];
 
     // Preserve the driver's existing Devices across a load→save (the device form authors the real endpoints;
@@ -154,7 +161,7 @@
         if (!string.Equals(_lastParsed, DriverConfigJson, StringComparison.Ordinal))
         {
             var opts = TryDeserialize(DriverConfigJson) ?? new AbCipDriverOptions();
-            _form = FormModel.FromOptions(opts);
+            _form = FormModel.FromJson(DriverConfigJson, opts);
             // #577: a brand-new driver (nothing authored yet) must not default the probe ON with no tag path —
             // that logs an operator warning per driver and runs no probe. An existing config keeps whatever
             // it stores (an absent "probe" key still means "enabled" to the driver, so don't flip it on edit).
@@ -173,7 +180,7 @@
 
     /// <summary>Serializes options with the form's JSON settings (camelCase, enums as strings).</summary>
     internal static string Serialize(AbCipDriverOptions options, string? originalJson = null)
-        => DriverConfigJsonOverlay.Apply(originalJson, JsonSerializer.Serialize(options, _jsonOpts), OwnedPaths);
+        => DriverConfigJsonOverlay.Apply(originalJson, JsonSerializer.Serialize(options, _jsonOpts), OwnedPaths, TimeSpanToMs);
 
     private async Task EmitAsync()
     {
@@ -222,8 +229,31 @@
         // Admin UI probe timeout
         public int AdminProbeTimeoutSeconds { get; set; } = 5;
 
+        // The loaded durations, so an unchanged seconds field saves the exact stored value (sub-second safe).
+        private TimeSpan? _loadedTimeout, _loadedAlarmPoll, _loadedProbeInterval, _loadedProbeTimeout;
+
+        /// <summary>Loads from the stored JSON: the factory's <c>*Ms</c> keys win; a legacy TimeSpan-string key is the fallback.</summary>
+        public static FormModel FromJson(string? json, AbCipDriverOptions o)
+        {
+            static TimeSpan? Ms(string? j, string path) => DriverConfigMs.Read(j, path) is int ms ? TimeSpan.FromMilliseconds(ms) : null;
+            var f = FromOptions(o);
+            f._loadedTimeout = Ms(json, "timeoutMs") ?? f._loadedTimeout;
+            f._loadedAlarmPoll = Ms(json, "alarmPollIntervalMs") ?? f._loadedAlarmPoll;
+            f._loadedProbeInterval = Ms(json, "probe.intervalMs") ?? f._loadedProbeInterval;
+            f._loadedProbeTimeout = Ms(json, "probe.timeoutMs") ?? f._loadedProbeTimeout;
+            f.TimeoutSeconds = DriverConfigMs.ToSeconds(f._loadedTimeout ?? o.Timeout);
+            f.AlarmPollIntervalSeconds = DriverConfigMs.ToSeconds(f._loadedAlarmPoll ?? o.AlarmPollInterval);
+            f.ProbeIntervalSeconds = DriverConfigMs.ToSeconds(f._loadedProbeInterval ?? o.Probe.Interval);
+            f.ProbeTimeoutSeconds = DriverConfigMs.ToSeconds(f._loadedProbeTimeout ?? o.Probe.Timeout);
+            return f;
+        }
+
         public static FormModel FromOptions(AbCipDriverOptions o) => new()
         {
+            _loadedTimeout = o.Timeout,
+            _loadedAlarmPoll = o.AlarmPollInterval,
+            _loadedProbeInterval = o.Probe.Interval,
+            _loadedProbeTimeout = o.Probe.Timeout,
             TimeoutSeconds = (int)o.Timeout.TotalSeconds,
             Transport = o.Transport,
             MaxConcurrentReads = o.MaxConcurrentReads,
@@ -245,16 +275,16 @@
             Probe = new AbCipProbeOptions
             {
                 Enabled = ProbeEnabled,
-                Interval = TimeSpan.FromSeconds(ProbeIntervalSeconds),
-                Timeout = TimeSpan.FromSeconds(ProbeTimeoutSeconds),
+                Interval = DriverConfigMs.Save(ProbeIntervalSeconds, _loadedProbeInterval),
+                Timeout = DriverConfigMs.Save(ProbeTimeoutSeconds, _loadedProbeTimeout),
                 ProbeTagPath = string.IsNullOrWhiteSpace(ProbeTagPath) ? null : ProbeTagPath,
             },
-            Timeout = TimeSpan.FromSeconds(TimeoutSeconds),
+            Timeout = DriverConfigMs.Save(TimeoutSeconds, _loadedTimeout),
             Transport = Transport,
             MaxConcurrentReads = MaxConcurrentReads,
             EnableControllerBrowse = EnableControllerBrowse,
             EnableAlarmProjection = EnableAlarmProjection,
-            AlarmPollInterval = TimeSpan.FromSeconds(AlarmPollIntervalSeconds),
+            AlarmPollInterval = DriverConfigMs.Save(AlarmPollIntervalSeconds, _loadedAlarmPoll),
             EnableDeclarationOnlyUdtGrouping = EnableDeclarationOnlyUdtGrouping,
             ProbeTimeoutSeconds = AdminProbeTimeoutSeconds,
         };
diff --git a/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Shared/Drivers/Forms/AbLegacyDriverForm.razor b/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Shared/Drivers/Forms/AbLegacyDriverForm.razor
index 972648de..9db2085a 100644
--- a/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Shared/Drivers/Forms/AbLegacyDriverForm.razor
+++ b/src/Server/ZB.MOM.WW.OtOpcUa.AdminUI/Components/Shared/Drivers/Forms/AbLegacyDriverForm.razor
@@ -97,8 +97,14 @@
     /// <summary>JSON paths this form edits; everything else in the stored config is preserved.</summary>
     internal static readonly string[] OwnedPaths =
     [
-        "timeout", "transport", "probeTimeoutSeconds",
-        "probe.enabled", "probe.interval", "probe.timeout", "probe.probeAddress",
+        "transport", "probeTimeoutSeconds",
+        "probe.enabled", "probe.probeAddress",
+    ];
+
+    /// <summary>The factory binds integer-millisecond keys, not the TimeSpan strings the typed options serialise (#576).</summary>
+    internal static readonly (string TimeSpanPath, string MsPath)[] TimeSpanToMs =
+    [
+        ("timeout", "timeoutMs"), ("probe.interval", "probe.intervalMs"), ("probe.timeout", "probe.timeoutMs"),
     ];
 
     // Devices are separate v3 entities — this form doesn't edit them, but preserves the driver's existing
@@ -111,7 +117,7 @@
         if (!string.Equals(_lastParsed, DriverConfigJson, StringComparison.Ordinal))
         {
             var opts = TryDeserialize(DriverConfigJson) ?? new AbLegacyDriverOptions();
-            _form = FormModel.FromOptions(opts);
+            _form = FormModel.FromJson(DriverConfigJson, opts);
             _originalJson = DriverConfigJson;
             _preservedDevices = opts.Devices;
             _lastParsed = DriverConfigJson;
@@ -125,7 +131,7 @@
 
     /// <summary>Serializes options with the form's JSON settings (camelCase, enums as strings).</summary>
     internal static string Serialize(AbLegacyDriverOptions options, string? originalJson = null)
-        => DriverConfigJsonOverlay.Apply(originalJson, JsonSerializer.Serialize(options, _jsonOpts), OwnedPaths);
+        => DriverConfigJsonOverlay.Apply(originalJson, JsonSerializer.Serialize(options, _jsonOpts), OwnedPaths, TimeSpanToMs);
 
     private async Task EmitAsync()
     {
@@ -171,8 +177,27 @@
         public string? ResilienceConfig { get; set; }
         public byte[] RowVersion { get; set; } = [];
 
+        private TimeSpan? _loadedTimeout, _loadedProbeInterval, _loadedProbeTimeout;
+
+        /// <summary>Loads from the stored JSON: the factory's <c>*Ms</c> keys win; a legacy TimeSpan-string key is the fallback.</summary>
+        public static FormModel FromJson(string? json, AbLegacyDriverOptions o)
+        {
+            static TimeSpan? Ms(string? j, string path) => DriverConfigMs.Read(j, path) is int ms ? TimeSpan.FromMilliseconds(ms) : null;
+            var f = FromOptions(o);
+            f._loadedTimeout = Ms(json, "timeoutMs") ?? f._loadedTimeout;
+            f._loadedProbeInterval = Ms(json, "probe.intervalMs") ?? f._loadedProbeInterval;
+            f._loadedProbeTimeout = Ms(json, "probe.timeoutMs") ?? f._loadedProbeTimeout;
+            f.TimeoutSeconds = DriverConfigMs.ToSeconds(f._loadedTimeout ?? o.Timeout);
+            f.ProbeIntervalSeconds = DriverConfigMs.ToSeconds(f._loadedProbeInterval ?? o.Probe.Interval);
+            f.ProbeTimeoutSeconds = DriverConfigMs.ToSeconds(f._loadedProbeTimeout ?? o.Probe.Timeout);
+            return f;
+        }
+
         public static FormModel FromOptions(AbLegacyDriverOptions o) => new()
         {
+            _loadedTimeout = o.Timeout,
+            _loadedProbeInterval = o.Probe.Interval,
+            _loadedProbeTimeout = o.Probe.Timeout,
             TimeoutSeconds = (int)o.Timeout.TotalSeconds,
             Transport = o.Transport,
             ProbeEnabled = o.Probe.Enabled,
@@ -189,11 +214,11 @@
             Probe = new AbLegacyProbeOptions
             {
                 Enabled = ProbeEnabled,
-                Interval = TimeSpan.FromSeconds(ProbeIntervalSeconds),
-                Timeout = TimeSpan.FromSeconds(ProbeTimeoutSeconds),
+                Interval = DriverConfigMs.Save(ProbeIntervalSeconds, _loadedProbeInterval),
+                Timeout = DriverConfigMs.Save(ProbeTimeoutSeconds, _loadedProbeTimeout),
                 ProbeAddress = string.IsNullOrWhiteSpace(ProbeAddress) ? null : ProbeAddress,
             },
-            Timeout = TimeSpan.FromSeconds(TimeoutSeconds),
+            Timeout = DriverConfigMs.Save(TimeoutSeconds, _loadedTimeout),
             Transport = Transport,
             ProbeTimeoutSeconds = AdminProbeTimeoutSeconds,
         };
diff --git a/tests/Server/ZB.MOM.WW.OtOpcUa.AdminUI.Tests/AbCipDriverPageFormSerializationTests.cs b/tests/Server/ZB.MOM.WW.OtOpcUa.AdminUI.Tests/AbCipDriverPageFormSerializationTests.cs
index 426d0bb4..9ac7ee98 100644
--- a/tests/Server/ZB.MOM.WW.OtOpcUa.AdminUI.Tests/AbCipDriverPageFormSerializationTests.cs
+++ b/tests/Server/ZB.MOM.WW.OtOpcUa.AdminUI.Tests/AbCipDriverPageFormSerializationTests.cs
@@ -141,7 +141,7 @@ public sealed class AbCipDriverPageFormSerializationTests
         var json = AbCipDriverForm.Serialize(form.ToOptions(loaded.Devices));
 
         json.ShouldContain($"\"transport\":\"{savedValue}\"");
-        json.ShouldContain("\"timeout\":\"00:00:07\"");
+        json.ShouldContain("\"timeoutMs\":7000");
     }
 
     [Fact]
@@ -158,7 +158,7 @@ public sealed class AbCipDriverPageFormSerializationTests
         form.TimeoutSeconds = 7;
         var json = AbCipDriverForm.Serialize(form.ToOptions(loaded.Devices));
         json.ShouldNotContain("transport", Case.Insensitive);
-        json.ShouldContain("\"timeout\":\"00:00:07\"");
+        json.ShouldContain("\"timeoutMs\":7000");
     }
 
     [Fact]
@@ -195,17 +195,18 @@ public sealed class AbCipDriverPageFormSerializationTests
         var root = System.Text.Json.Nodes.JsonNode.Parse(
             AbCipDriverForm.Serialize(form.ToOptions(loaded.Devices), FullConfig))!.AsObject();
 
-        root["timeout"]!.GetValue<string>().ShouldBe("00:00:09");
+        root["timeoutMs"]!.GetValue<int>().ShouldBe(9000);
+        root.ContainsKey("timeout").ShouldBeFalse();
         root["maxConcurrentReads"]!.GetValue<int>().ShouldBe(3); // was reset to 8 before #576
         root["transport"]!.GetValue<string>().ShouldBe("Native");
         root["enableControllerBrowse"]!.GetValue<bool>().ShouldBeTrue();
         root["enableDeclarationOnlyUdtGrouping"]!.GetValue<bool>().ShouldBeTrue();
         root["enableAlarmProjection"]!.GetValue<bool>().ShouldBeTrue();
-        root["alarmPollInterval"]!.GetValue<string>().ShouldBe("00:00:02");
+        root["alarmPollIntervalMs"]!.GetValue<int>().ShouldBe(2000);
         root["probeTimeoutSeconds"]!.GetValue<int>().ShouldBe(12);
         root["probe"]!["enabled"]!.GetValue<bool>().ShouldBeTrue();
-        root["probe"]!["interval"]!.GetValue<string>().ShouldBe("00:00:10");
-        root["probe"]!["timeout"]!.GetValue<string>().ShouldBe("00:00:03");
+        root["probe"]!["intervalMs"]!.GetValue<int>().ShouldBe(10000);
+        root["probe"]!["timeoutMs"]!.GetValue<int>().ShouldBe(3000);
         root["probe"]!["probeTagPath"]!.GetValue<string>().ShouldBe("Program:Main.Hb");
         // unknown keys at every level survive
         root["probe"]!["futureProbeKnob"]!.GetValue<int>().ShouldBe(7);
@@ -245,4 +246,64 @@ public sealed class AbCipDriverPageFormSerializationTests
         json.ShouldContain("\"transport\":\"Libplctag\"");
         json.ShouldContain("futureOption");
     }
+
+    // ---- #576: the saved JSON must be what the driver FACTORY binds (integer-ms keys) ----
+
+    [Fact]
+    public void An_edited_timeout_reaches_the_factory_bound_options()
+    {
+        var original = """{"timeoutMs":5000,"alarmPollIntervalMs":500,"probe":{"enabled":true,"intervalMs":7000,"timeoutMs":1500,"probeTagPath":"Program:Main.Hb"},"devices":[{"hostAddress":"ab://10.0.0.1/1,0"}]}""";
+        var loaded = AbCipDriverForm.TryDeserialize(original)!;
+        var form = AbCipDriverForm.FormModel.FromJson(original, loaded);
+        form.TimeoutSeconds.ShouldBe(5); // the form SEES the factory-keyed value
+        form.TimeoutSeconds = 11;
+
+        var saved = AbCipDriverForm.Serialize(form.ToOptions(loaded.Devices), original);
+        var bound = ZB.MOM.WW.OtOpcUa.Driver.AbCip.AbCipDriverFactoryExtensions.ParseOptions("t", saved);
+
+        bound.Timeout.ShouldBe(TimeSpan.FromSeconds(11));
+        // untouched durations keep their exact stored value, including sub-second ones
+        bound.AlarmPollInterval.ShouldBe(TimeSpan.FromMilliseconds(500));
+        bound.Probe.Interval.ShouldBe(TimeSpan.FromSeconds(7));
+        bound.Probe.Timeout.ShouldBe(TimeSpan.FromMilliseconds(1500));
+        bound.Probe.ProbeTagPath.ShouldBe("Program:Main.Hb");
+    }
+
+    [Fact]
+    public void A_legacy_TimeSpan_string_key_is_loaded_then_migrated_to_ms_and_removed()
+    {
+        var original = """{"timeout":"00:00:05","alarmPollInterval":"00:00:02","probe":{"interval":"00:00:10","timeout":"00:00:03"}}""";
+        var loaded = AbCipDriverForm.TryDeserialize(original)!;
+        var form = AbCipDriverForm.FormModel.FromJson(original, loaded);
+        form.TimeoutSeconds.ShouldBe(5);
+        form.TimeoutSeconds = 6;
+
+        var saved = AbCipDriverForm.Serialize(form.ToOptions(loaded.Devices), original);
+        var root = System.Text.Json.Nodes.JsonNode.Parse(saved)!.AsObject();
+        root.ContainsKey("timeout").ShouldBeFalse();
+        root.ContainsKey("alarmPollInterval").ShouldBeFalse();
+        root["probe"]!.AsObject().ContainsKey("interval").ShouldBeFalse();
+        root["probe"]!.AsObject().ContainsKey("timeout").ShouldBeFalse();
+
+        var bound = ZB.MOM.WW.OtOpcUa.Driver.AbCip.AbCipDriverFactoryExtensions.ParseOptions("t", saved);
+        bound.Timeout.ShouldBe(TimeSpan.FromSeconds(6));
+        bound.AlarmPollInterval.ShouldBe(TimeSpan.FromSeconds(2));
+        bound.Probe.Interval.ShouldBe(TimeSpan.FromSeconds(10));
+        bound.Probe.Timeout.ShouldBe(TimeSpan.FromSeconds(3));
+    }
+
+    [Fact]
+    public void A_form_saved_config_is_still_accepted_by_the_Test_Connect_probe_parse()
+    {
+        // The probe deserialises the typed options and skips unmapped keys, so the ms keys must not break it.
+        var original = """{"timeoutMs":5000,"devices":[{"hostAddress":"ab://10.0.0.1/1,0"}]}""";
+        var loaded = AbCipDriverForm.TryDeserialize(original)!;
+        var form = AbCipDriverForm.FormModel.FromJson(original, loaded);
+        form.TimeoutSeconds = 8;
+        var saved = AbCipDriverForm.Serialize(form.ToOptions(loaded.Devices), original);
+
+        var opts = System.Text.Json.JsonSerializer.Deserialize<AbCipDriverOptions>(saved, TestJsonOpts);
+        opts.ShouldNotBeNull();
+        opts.Devices[0].HostAddress.ShouldBe("ab://10.0.0.1/1,0");
+    }
 }
diff --git a/tests/Server/ZB.MOM.WW.OtOpcUa.AdminUI.Tests/AbLegacyDriverPageFormSerializationTests.cs b/tests/Server/ZB.MOM.WW.OtOpcUa.AdminUI.Tests/AbLegacyDriverPageFormSerializationTests.cs
index 2df3c36b..f4297127 100644
--- a/tests/Server/ZB.MOM.WW.OtOpcUa.AdminUI.Tests/AbLegacyDriverPageFormSerializationTests.cs
+++ b/tests/Server/ZB.MOM.WW.OtOpcUa.AdminUI.Tests/AbLegacyDriverPageFormSerializationTests.cs
@@ -137,7 +137,7 @@ public sealed class AbLegacyDriverPageFormSerializationTests
         var json = AbLegacyDriverForm.Serialize(form.ToOptions(loaded.Devices));
 
         json.ShouldContain($"\"transport\":\"{savedValue}\"");
-        json.ShouldContain("\"timeout\":\"00:00:07\"");
+        json.ShouldContain("\"timeoutMs\":7000");
     }
 
     [Fact]
@@ -153,7 +153,7 @@ public sealed class AbLegacyDriverPageFormSerializationTests
         form.TimeoutSeconds = 7;
         var json = AbLegacyDriverForm.Serialize(form.ToOptions(loaded.Devices));
         json.ShouldNotContain("transport", Case.Insensitive);
-        json.ShouldContain("\"timeout\":\"00:00:07\"");
+        json.ShouldContain("\"timeoutMs\":7000");
     }
 
     [Fact]
@@ -208,12 +208,13 @@ public sealed class AbLegacyDriverPageFormSerializationTests
         var root = System.Text.Json.Nodes.JsonNode.Parse(
             AbLegacyDriverForm.Serialize(form.ToOptions(loaded.Devices), FullConfig))!.AsObject();
 
-        root["timeout"]!.GetValue<string>().ShouldBe("00:00:09");
+        root["timeoutMs"]!.GetValue<int>().ShouldBe(9000);
+        root.ContainsKey("timeout").ShouldBeFalse();
         root["transport"]!.GetValue<string>().ShouldBe("Native");
         root["probeTimeoutSeconds"]!.GetValue<int>().ShouldBe(12);
         root["probe"]!["enabled"]!.GetValue<bool>().ShouldBeTrue();
-        root["probe"]!["interval"]!.GetValue<string>().ShouldBe("00:00:10");
-        root["probe"]!["timeout"]!.GetValue<string>().ShouldBe("00:00:03");
+        root["probe"]!["intervalMs"]!.GetValue<int>().ShouldBe(10000);
+        root["probe"]!["timeoutMs"]!.GetValue<int>().ShouldBe(3000);
         root["probe"]!["probeAddress"]!.GetValue<string>().ShouldBe("S:1");
         root["probe"]!["futureProbeKnob"]!.GetValue<int>().ShouldBe(7);
         root["devices"]![0]!["futureDeviceKey"]!.GetValue<string>().ShouldBe("keep");
@@ -234,4 +235,45 @@ public sealed class AbLegacyDriverPageFormSerializationTests
         root.ContainsKey("transport").ShouldBeFalse();
         root["futureOption"].ShouldNotBeNull();
     }
+
+    // ---- #576: the saved JSON must be what the driver FACTORY binds (integer-ms keys) ----
+
+    [Fact]
+    public void An_edited_timeout_reaches_the_factory_bound_options()
+    {
+        var original = """{"timeoutMs":5000,"probe":{"enabled":true,"intervalMs":7000,"timeoutMs":1500,"probeAddress":"S:1"},"devices":[{"hostAddress":"ab://10.0.0.1/1,0","plcFamily":"Slc500"}]}""";
+        var loaded = AbLegacyDriverForm.TryDeserialize(original)!;
+        var form = AbLegacyDriverForm.FormModel.FromJson(original, loaded);
+        form.TimeoutSeconds.ShouldBe(5);
+        form.TimeoutSeconds = 11;
+
+        var saved = AbLegacyDriverForm.Serialize(form.ToOptions(loaded.Devices), original);
+        var bound = ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.AbLegacyDriverFactoryExtensions.ParseOptions("t", saved);
+
+        bound.Timeout.ShouldBe(TimeSpan.FromSeconds(11));
+        bound.Probe.Interval.ShouldBe(TimeSpan.FromSeconds(7));
+        bound.Probe.Timeout.ShouldBe(TimeSpan.FromMilliseconds(1500));
+        bound.Probe.ProbeAddress.ShouldBe("S:1");
+    }
+
+    [Fact]
+    public void A_legacy_TimeSpan_string_key_is_loaded_then_migrated_to_ms_and_removed()
+    {
+        var original = """{"timeout":"00:00:05","probe":{"interval":"00:00:10","timeout":"00:00:03"}}""";
+        var loaded = AbLegacyDriverForm.TryDeserialize(original)!;
+        var form = AbLegacyDriverForm.FormModel.FromJson(original, loaded);
+        form.TimeoutSeconds.ShouldBe(5);
+        form.TimeoutSeconds = 6;
+
+        var saved = AbLegacyDriverForm.Serialize(form.ToOptions(loaded.Devices), original);
+        var root = System.Text.Json.Nodes.JsonNode.Parse(saved)!.AsObject();
+        root.ContainsKey("timeout").ShouldBeFalse();
+        root["probe"]!.AsObject().ContainsKey("interval").ShouldBeFalse();
+        root["probe"]!.AsObject().ContainsKey("timeout").ShouldBeFalse();
+
+        var bound = ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.AbLegacyDriverFactoryExtensions.ParseOptions("t", saved);
+        bound.Timeout.ShouldBe(TimeSpan.FromSeconds(6));
+        bound.Probe.Interval.ShouldBe(TimeSpan.FromSeconds(10));
+        bound.Probe.Timeout.ShouldBe(TimeSpan.FromSeconds(3));
+    }
 }
diff --git a/tests/Server/ZB.MOM.WW.OtOpcUa.AdminUI.Tests/ZB.MOM.WW.OtOpcUa.AdminUI.Tests.csproj b/tests/Server/ZB.MOM.WW.OtOpcUa.AdminUI.Tests/ZB.MOM.WW.OtOpcUa.AdminUI.Tests.csproj
index ba5aba32..742ab993 100644
--- a/tests/Server/ZB.MOM.WW.OtOpcUa.AdminUI.Tests/ZB.MOM.WW.OtOpcUa.AdminUI.Tests.csproj
+++ b/tests/Server/ZB.MOM.WW.OtOpcUa.AdminUI.Tests/ZB.MOM.WW.OtOpcUa.AdminUI.Tests.csproj
@@ -37,6 +37,9 @@
              project referencing a runtime driver is fine — tests are not in the AdminUI's deploy
              graph, which is the whole thing #526 was about. -->
         <ProjectReference Include="..\..\..\src\Drivers\ZB.MOM.WW.OtOpcUa.Driver.Sql\ZB.MOM.WW.OtOpcUa.Driver.Sql.csproj"/>
+        <!-- #576: the AB form tests deserialise the saved JSON through the drivers' own factory parse. -->
+        <ProjectReference Include="..\..\..\src\Drivers\ZB.MOM.WW.OtOpcUa.Driver.AbCip\ZB.MOM.WW.OtOpcUa.Driver.AbCip.csproj"/>
+        <ProjectReference Include="..\..\..\src\Drivers\ZB.MOM.WW.OtOpcUa.Driver.AbLegacy\ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.csproj"/>
     </ItemGroup>
 
 </Project>