fix(focas): decode servo/spindle meters by their base/exponent envelope; MaxRpm -> MotorSpeedPct

Servo (0x0056) and spindle (0x0040) meter records are 8 bytes:
[i32 value][u16 base][u16 exponent], the same self-describing envelope as the
position blocks.

Servo: offset 4 was read as a decimal count. It is the BASE (a steady 10), so
every load was divided by 10^10 and published ~0 -- the sister ignitionoee panel
read servo 0% on every axis of a Makino cutting at 20,000 rpm. Loads are now
value / base^exponent, a direct percentage.

Spindle: the raw meter is a 1/16384 fraction of full scale. Settled on the real
Z-34184 by regressing the type-1 meter against cnc_rddynamic2 spindle speed over
596..20,000 rpm (rpm = 1.220749 x meter; 16384 x 1.220749 = 20000.75). So:
- Spindle/{name}/Load publishes % of rated load (Float64; was the raw Int32
  count -- a reading of 9155 meant 55.9%).
- Spindle/{name}/MaxRpm is RENAMED Spindle/{name}/MotorSpeedPct (Float64, % of
  maximum speed) and is polled with Load. The old node was actively wrong: the
  type-1 meter is the live motor speed, and it was read once at bootstrap and
  served forever as if it were a max-RPM constant. Client-visible: FIXED: tags
  on .../MaxRpm must be re-pointed.
- The spindle read no longer stops at the first zero after slot 1 (which dropped
  an idle second spindle and kept non-zero residue); every slot is returned.

A record whose envelope is undescribable (base not 2/10, exponent > 18 -- e.g.
residue past the configured axis/spindle count) publishes BadNoData, never a Good 0.

Ported from the sister ignitionoee FOCAS driver v0.17.2/v0.17.3 (Focas.Wire-019);
live captures live-spmeter-{load,maxrpm}-0x0040.bin added as fixtures.

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.FOCAS/FocasDriver.cs

@@ -643,7 +643,8 @@ public sealed class FocasDriver : IDriver, IReadable, IWritable, ITagDiscovery,
 
                 // Spindle subtree — one folder per discovered spindle, suppressed
                 // entirely on series that don't export cnc_rdspdlname. Per-spindle
-                // Load + MaxRpm each gated on their own capability probe.
+                // Load + MotorSpeedPct (both cnc_rdspmeter percentages of full scale)
+                // each gated on their own capability probe.
                 if (cache.Capabilities.Spindles)
                 {
                     var spindleRoot = deviceFolder.Folder("Spindle", "Spindle");
@@ -652,9 +653,9 @@ public sealed class FocasDriver : IDriver, IReadable, IWritable, ITagDiscovery,
                         var name = cache.SpindleSegments[i];
                         var spindleFolder = spindleRoot.Folder(name, name);
                         if (cache.Capabilities.SpindleLoad)
-                            EmitFixedVariable(spindleFolder, $"Spindle/{name}", "Load", DriverDataType.Int32);
+                            EmitFixedVariable(spindleFolder, $"Spindle/{name}", "Load", DriverDataType.Float64);
-                        if (cache.Capabilities.SpindleMaxRpm && i < cache.SpindleMaxRpms.Count)
+                        if (cache.Capabilities.SpindleMotorSpeed)
-                            EmitFixedVariable(spindleFolder, $"Spindle/{name}", "MaxRpm", DriverDataType.Int32);
+                            EmitFixedVariable(spindleFolder, $"Spindle/{name}", "MotorSpeedPct", DriverDataType.Float64);
                     }
                 }
 
@@ -927,7 +928,7 @@ public sealed class FocasDriver : IDriver, IReadable, IWritable, ITagDiscovery,
 
                 // Optional-API probes — each returns empty / throws when unsupported.
                 var spindles = await SafeProbe(() => client.GetSpindleNamesAsync(ct), []);
-                var spindleMaxRpms = await SafeProbe(() => client.GetSpindleMaxRpmsAsync(ct), []);
+                var spindleMotorSpeeds = await SafeProbe(() => client.GetSpindleMotorSpeedsAsync(ct), []);
                 var servoLoads = await SafeProbe(() => client.GetServoLoadsAsync(ct), []);
                 var programInfo = await SafeTryProbe(() => client.GetProgramInfoAsync(ct));
                 var timer = await SafeTryProbe(() => client.GetTimerAsync(FocasTimerKind.PowerOn, ct));
@@ -936,13 +937,12 @@ public sealed class FocasDriver : IDriver, IReadable, IWritable, ITagDiscovery,
                 var caps = new FocasFixedTreeCapabilities(
                     Spindles: spindles.Count > 0,
                     SpindleLoad: spindleLoad.Count > 0,
-                    SpindleMaxRpm: spindleMaxRpms.Count > 0,
+                    SpindleMotorSpeed: spindleMotorSpeeds.Count > 0,
                     ServoLoad: servoLoads.Count > 0,
                     ProgramInfo: programInfo is not null,
                     Timers: timer is not null);
 
-                state.FixedTreeCache = new FocasFixedTreeCache(
+                state.FixedTreeCache = new FocasFixedTreeCache(sys, [.. axes], [.. spindles], caps);
-                    sys, [.. axes], [.. spindles], [.. spindleMaxRpms], caps);
                 // The bootstrap IS an answer from the device, and Identity comes entirely from it —
                 // so stamp liveness here as well as per tick, or a CNC whose axis poll never
                 // succeeds would serve a perfectly valid sysinfo as stale.
@@ -958,15 +958,14 @@ public sealed class FocasDriver : IDriver, IReadable, IWritable, ITagDiscovery,
             }
         }
 
-        // Prime the spindle-loads cache from bootstrap if supported — avoids a
+        // Prime the spindle-meter caches from bootstrap if supported — avoids a
         // "tree is there but reads say BadNodeIdUnknown" window on startup.
-        if (state.FixedTreeCache?.Capabilities is { SpindleLoad: true })
+        if (state.FixedTreeCache?.Capabilities is { SpindleLoad: true } or { SpindleMotorSpeed: true })
         {
             try
             {
                 var client2 = await EnsureConnectedAsync(state, ct).ConfigureAwait(false);
-                var loads = await client2.GetSpindleLoadsAsync(ct).ConfigureAwait(false);
+                await PollSpindleMetersAsync(state, client2, ct).ConfigureAwait(false);
-                for (var i = 0; i < loads.Count; i++) state.LastSpindleLoads[i] = loads[i];
             }
             catch (Exception ex)
             {
@@ -1019,17 +1018,16 @@ public sealed class FocasDriver : IDriver, IReadable, IWritable, ITagDiscovery,
                             state.Options.HostAddress);
                     }
                 }
-                if (cache.Capabilities.SpindleLoad)
+                if (cache.Capabilities.SpindleLoad || cache.Capabilities.SpindleMotorSpeed)
                 {
                     try
                     {
-                        var loads = await client.GetSpindleLoadsAsync(ct).ConfigureAwait(false);
+                        await PollSpindleMetersAsync(state, client, ct).ConfigureAwait(false);
-                        for (var i = 0; i < loads.Count; i++) state.LastSpindleLoads[i] = loads[i];
                     }
                     catch (Exception ex)
                     {
                         /* transient */
-                        _logger.LogDebug(ex, "FOCAS spindle-loads poll failed for {Host}",
+                        _logger.LogDebug(ex, "FOCAS spindle-meter poll failed for {Host}",
                             state.Options.HostAddress);
                     }
                 }
@@ -1148,7 +1146,27 @@ public sealed class FocasDriver : IDriver, IReadable, IWritable, ITagDiscovery,
     {
         var segments = FixedTreeNames.Disambiguate(loads.Select(l => l.AxisName));
         for (var i = 0; i < loads.Count; i++)
-            state.LastServoLoads[segments[i]] = loads[i].LoadPercent;
+            state.LastServoLoads[segments[i]] = loads[i].LoadPercent ?? NoValue;
+    }
+
+    /// <summary>
+    ///     Read and cache both spindle meters (load, motor speed) — each a <c>cnc_rdspmeter</c>
+    ///     percentage of full scale (16384 = 100%) — for every spindle slot, as capability allows.
+    ///     A slot whose record describes no value is cached as <see cref="NoValue"/> (BadNoData).
+    /// </summary>
+    private static async Task PollSpindleMetersAsync(DeviceState state, IFocasClient client, CancellationToken ct)
+    {
+        var caps = state.FixedTreeCache?.Capabilities;
+        if (caps is { SpindleLoad: true })
+        {
+            var loads = await client.GetSpindleLoadsAsync(ct).ConfigureAwait(false);
+            for (var i = 0; i < loads.Count; i++) state.LastSpindleLoads[i] = loads[i] ?? NoValue;
+        }
+        if (caps is { SpindleMotorSpeed: true })
+        {
+            var speeds = await client.GetSpindleMotorSpeedsAsync(ct).ConfigureAwait(false);
+            for (var i = 0; i < speeds.Count; i++) state.LastSpindleMotorSpeeds[i] = speeds[i] ?? NoValue;
+        }
     }
 
     private static object? TimerValue(DeviceState state, FocasTimerKind kind) =>
@@ -1240,7 +1258,7 @@ public sealed class FocasDriver : IDriver, IReadable, IWritable, ITagDiscovery,
                 return CachedDouble(load, status, sourceUtc, now);
         }
 
-        // Spindle matches: "Spindle/{name}/Load" + "Spindle/{name}/MaxRpm"
+        // Spindle matches: "Spindle/{name}/Load" + "Spindle/{name}/MotorSpeedPct"
         if (suffixFull.StartsWith("Spindle/", StringComparison.Ordinal)
             && state.FixedTreeCache is { } spindleCache)
         {
@@ -1259,14 +1277,14 @@ public sealed class FocasDriver : IDriver, IReadable, IWritable, ITagDiscovery,
                 }
                 if (idx >= 0)
                 {
-                    object? value = field switch
+                    var meters = field switch
                     {
-                        "Load" => state.LastSpindleLoads.TryGetValue(idx, out var l) ? (object)l : null,
+                        "Load" => state.LastSpindleLoads,
-                        "MaxRpm" => idx < spindleCache.SpindleMaxRpms.Count ? (object)spindleCache.SpindleMaxRpms[idx] : null,
+                        "MotorSpeedPct" => state.LastSpindleMotorSpeeds,
                         _ => null,
                     };
-                    if (value is not null)
+                    if (meters is not null && meters.TryGetValue(idx, out var pct))
-                        return new DataValueSnapshot(value, status, sourceUtc, now);
+                        return CachedDouble(pct, status, sourceUtc, now);
                 }
             }
         }
@@ -1477,7 +1495,6 @@ public sealed class FocasDriver : IDriver, IReadable, IWritable, ITagDiscovery,
         FocasSysInfo SysInfo,
         IReadOnlyList<FocasAxisName> Axes,
         IReadOnlyList<FocasSpindleName> Spindles,
-        IReadOnlyList<int> SpindleMaxRpms,
         FocasFixedTreeCapabilities Capabilities)
     {
         /// <summary>
@@ -1503,14 +1520,14 @@ public sealed class FocasDriver : IDriver, IReadable, IWritable, ITagDiscovery,
     /// <summary>
     ///     Per-device optional-API capability flags — which of the "this may or may not
     ///     exist on this CNC series" calls succeeded at bootstrap. Drives per-series
-    ///     node suppression so a 16i that doesn't export <c>cnc_rdspmaxrpm</c> simply
+    ///     node suppression so a 16i that doesn't export <c>cnc_rdspmeter</c> simply
-    ///     doesn't get a <c>Spindle/{name}/MaxRpm</c> node (instead of surfacing
+    ///     doesn't get a <c>Spindle/{name}/MotorSpeedPct</c> node (instead of surfacing
     ///     <c>BadDeviceFailure</c> on every read).
     /// </summary>
     internal sealed record FocasFixedTreeCapabilities(
         bool Spindles,          // cnc_rdspdlname returned 1+ spindle names
-        bool SpindleLoad,       // cnc_rdspload bootstrap probe succeeded
+        bool SpindleLoad,       // cnc_rdspmeter type 0 (load) bootstrap probe succeeded
-        bool SpindleMaxRpm,     // cnc_rdspmaxrpm bootstrap probe succeeded
+        bool SpindleMotorSpeed, // cnc_rdspmeter type 1 (motor speed) bootstrap probe succeeded
         bool ServoLoad,         // cnc_rdsvmeter bootstrap probe returned data
         bool ProgramInfo,       // cnc_exeprgname2 + cnc_rdblkcount + cnc_rdopmode work
         bool Timers);           // cnc_rdtimer works for at least PowerOn
@@ -1580,8 +1597,16 @@ public sealed class FocasDriver : IDriver, IReadable, IWritable, ITagDiscovery,
         public ConcurrentDictionary<FocasTimerKind, FocasTimer> LastTimers { get; } = new();
         /// <summary>Gets the last servo load percentages by servo name.</summary>
         public ConcurrentDictionary<string, double> LastServoLoads { get; } = new(StringComparer.OrdinalIgnoreCase);
-        /// <summary>Gets the last spindle load percentages by spindle index.</summary>
+        /// <summary>
-        public ConcurrentDictionary<int, int> LastSpindleLoads { get; } = new();
+        ///     Gets the last spindle load percentages (% of rated load) by spindle index;
+        ///     <see cref="NoValue"/> for a slot the CNC described as holding none.
+        /// </summary>
+        public ConcurrentDictionary<int, double> LastSpindleLoads { get; } = new();
+        /// <summary>
+        ///     Gets the last spindle motor-speed percentages (% of maximum speed) by spindle index;
+        ///     <see cref="NoValue"/> for a slot the CNC described as holding none.
+        /// </summary>
+        public ConcurrentDictionary<int, double> LastSpindleMotorSpeeds { get; } = new();
 
         /// <summary>Disposes the FOCAS client instance.</summary>
         public void DisposeClient()

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.FOCAS/IFocasClient.cs

@@ -140,9 +140,10 @@ public interface IFocasClient : IDisposable
     // ---- Fixed-tree T3.5 (servo meters) ----
 
     /// <summary>
-    ///     Read the servo-load meter percentages across all configured axes.
+    ///     Read the servo-load meter percentages across all configured axes. Each record's own
-    ///     Values are percentages (scaled by <c>10^Dec</c>). Empty list on a
+    ///     <c>value / base^exponent</c> envelope is applied (servo loads are direct percentages);
-    ///     disconnected session or unsupported CNC.
+    ///     a record whose envelope describes no value carries a null <see cref="FocasServoLoad.LoadPercent"/>.
+    ///     Empty list on a disconnected session or unsupported CNC.
     /// </summary>
     /// <param name="cancellationToken">The cancellation token.</param>
     /// <returns>The servo-load meter percentages across all configured axes.</returns>
@@ -151,26 +152,31 @@ public interface IFocasClient : IDisposable
     // ---- Fixed-tree T3.6 (spindle meters) ----
 
     /// <summary>
-    ///     Read per-spindle load percentages. Result list index corresponds to
+    ///     Read per-spindle load as a percentage of rated load (<c>cnc_rdspmeter</c> type 0; the
-    ///     spindle index from <see cref="GetSpindleNamesAsync"/>. Empty list on a
+    ///     raw meter is a 1/16384 fraction of full scale). Result list index corresponds to
-    ///     disconnected session or when the CNC doesn't support the call (older
+    ///     spindle index from <see cref="GetSpindleNamesAsync"/>; a slot whose record describes no
-    ///     series like 16i may return EW_FUNC).
+    ///     value is null. Empty list on a disconnected session or when the CNC doesn't support the
+    ///     call (older series like 16i may return EW_FUNC).
     /// </summary>
     /// <param name="cancellationToken">The cancellation token.</param>
     /// <returns>Per-spindle load percentages, indexed as per <see cref="GetSpindleNamesAsync"/>.</returns>
-    Task<IReadOnlyList<int>> GetSpindleLoadsAsync(CancellationToken cancellationToken);
+    Task<IReadOnlyList<double?>> GetSpindleLoadsAsync(CancellationToken cancellationToken);
 
     /// <summary>
-    ///     Read per-spindle maximum RPM values. Static configuration, fetched once at
+    ///     Read per-spindle motor speed as a percentage of maximum speed (<c>cnc_rdspmeter</c>
-    ///     bootstrap. Index alignment as per <see cref="GetSpindleLoadsAsync"/>.
+    ///     type 1, historically labelled <c>cnc_rdspmaxrpm</c>). A live value, not a max-RPM
+    ///     constant. Index alignment and null semantics as per <see cref="GetSpindleLoadsAsync"/>.
     /// </summary>
     /// <param name="cancellationToken">The cancellation token.</param>
-    /// <returns>Per-spindle maximum RPM values, indexed as per <see cref="GetSpindleLoadsAsync"/>.</returns>
+    /// <returns>Per-spindle motor-speed percentages, indexed as per <see cref="GetSpindleLoadsAsync"/>.</returns>
-    Task<IReadOnlyList<int>> GetSpindleMaxRpmsAsync(CancellationToken cancellationToken);
+    Task<IReadOnlyList<double?>> GetSpindleMotorSpeedsAsync(CancellationToken cancellationToken);
 }
 
-/// <summary>One servo-meter entry — one axis's current load percentage.</summary>
+/// <summary>
-public sealed record FocasServoLoad(string AxisName, double LoadPercent);
+///     One servo-meter entry — one axis's current load percentage; null when the CNC's record
+///     described no usable value (never a fabricated 0).
+/// </summary>
+public sealed record FocasServoLoad(string AxisName, double? LoadPercent);
 
 /// <summary>Which cumulative counter <see cref="IFocasClient.GetTimerAsync"/> reads.</summary>
 public enum FocasTimerKind
@@ -297,19 +303,16 @@ public sealed record FocasDynamicSnapshot(
 /// </param>
 public readonly record struct FocasPosition(int Raw, int Base = 0, int Exponent = 0, bool HasScale = false)
 {
-    /// <summary>
-    ///     Largest exponent that can describe a real coordinate. An i32 carries at most ten digits,
-    ///     so anything beyond is a misread block — and left unbounded, <c>raw / 10^400</c> is
-    ///     <c>raw / Infinity = 0.0</c>, a Good reading of a machine parked at the origin.
-    /// </summary>
-    public const int MaxExponent = 18;
-
     /// <summary>
     ///     False when the block says it holds no usable position: the <c>0xFFFF</c> vacant marker, a
     ///     base other than 2 or 10, or an absurd exponent. A per-node quality decision — that node
     ///     publishes Bad, its siblings are unaffected.
     /// </summary>
-    public bool IsValid => !HasScale || (Exponent <= MaxExponent && Base is 2 or 10);
+    /// <remarks>
+    ///     The exponent bound matters: left unbounded, <c>raw / 10^400</c> is
+    ///     <c>raw / Infinity = 0.0</c> — a Good reading of a machine parked at the origin.
+    /// </remarks>
+    public bool IsValid => !HasScale || Wire.FocasValueEnvelope.IsValid(Base, Exponent);
 
     /// <summary>
     ///     The position in engineering units: <c>Raw / Base^Exponent</c> when the block carried its
@@ -321,7 +324,7 @@ public readonly record struct FocasPosition(int Raw, int Base = 0, int Exponent
     public double? ToEngineering(int fallbackDecimalPlaces)
     {
         if (!IsValid) return null;
-        if (HasScale) return Exponent == 0 ? Raw : Raw / Math.Pow(Base, Exponent);
+        if (HasScale) return Wire.FocasValueEnvelope.Scale(Raw, Base, Exponent);
         var dp = Math.Max(0, fallbackDecimalPlaces);
         return dp > 0 ? Raw / Math.Pow(10, dp) : Raw;
     }

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.FOCAS/SynchronizedFocasClient.cs

@@ -99,12 +99,12 @@ public sealed class SynchronizedFocasClient : IFocasClient
         RunBoundedAsync(ct => _inner.GetServoLoadsAsync(ct), cancellationToken);
 
     /// <inheritdoc />
-    public Task<IReadOnlyList<int>> GetSpindleLoadsAsync(CancellationToken cancellationToken) =>
+    public Task<IReadOnlyList<double?>> GetSpindleLoadsAsync(CancellationToken cancellationToken) =>
         RunBoundedAsync(ct => _inner.GetSpindleLoadsAsync(ct), cancellationToken);
 
     /// <inheritdoc />
-    public Task<IReadOnlyList<int>> GetSpindleMaxRpmsAsync(CancellationToken cancellationToken) =>
+    public Task<IReadOnlyList<double?>> GetSpindleMotorSpeedsAsync(CancellationToken cancellationToken) =>
-        RunBoundedAsync(ct => _inner.GetSpindleMaxRpmsAsync(ct), cancellationToken);
+        RunBoundedAsync(ct => _inner.GetSpindleMotorSpeedsAsync(ct), cancellationToken);
 
     /// <summary>Disposes the inner client and the call gate.</summary>
     public void Dispose()

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.FOCAS/Wire/FocasWireClient.cs

@@ -420,12 +420,15 @@ public sealed class FocasWireClient : IAsyncDisposable, IDisposable
         return new FocasResult<IReadOnlyList<WireServoMeter>>(rc, result);
     }
 
-    /// <summary>Read per-spindle load percentages via <c>cnc_rdspload</c> (command <c>0x0040</c> with arg1=0).</summary>
+    /// <summary>
+    ///     Read the per-spindle load meter via <c>cnc_rdspmeter</c> (command <c>0x0040</c>, type 0).
+    ///     <see cref="WireSpindleMetric.Percent"/> is % of rated load (16384 = 100%).
+    /// </summary>
     /// <param name="spindleSelector">Spindle selector; -1 selects all spindles.</param>
     /// <param name="cancellationToken">Cancellation token for the read operation.</param>
     /// <param name="timeout">Optional per-call timeout override.</param>
     /// <param name="pathId">Optional path ID override; defaults to <see cref="PathId"/>.</param>
-    /// <returns>The per-spindle load percentages, wrapped in a <see cref="FocasResult{T}"/>.</returns>
+    /// <returns>The per-spindle load meters, wrapped in a <see cref="FocasResult{T}"/>.</returns>
     public Task<FocasResult<IReadOnlyList<WireSpindleMetric>>> ReadSpindleLoadAsync(
         short spindleSelector = -1,
         CancellationToken cancellationToken = default,
@@ -433,13 +436,19 @@ public sealed class FocasWireClient : IAsyncDisposable, IDisposable
         ushort? pathId = null)
         => ReadSpindleMetricAsync(0, spindleSelector, cancellationToken, timeout, pathId);
 
-    /// <summary>Read per-spindle maximum RPMs via <c>cnc_rdspmaxrpm</c> (command <c>0x0040</c> with arg1=1).</summary>
+    /// <summary>
+    ///     Read the per-spindle motor-speed meter via <c>cnc_rdspmeter</c> (command <c>0x0040</c>,
+    ///     type 1 — historically labelled <c>cnc_rdspmaxrpm</c>). It is NOT a maximum-RPM constant:
+    ///     it is the live motor speed as a fraction of maximum, <see cref="WireSpindleMetric.Percent"/>
+    ///     (a regression against <c>cnc_rddynamic2</c> spindle speed on a real 31i-B gives
+    ///     <c>rpm = 1.220749 × meter</c>, i.e. 16384 = the spindle's 20,000 rpm maximum).
+    /// </summary>
     /// <param name="spindleSelector">Spindle selector; -1 selects all spindles.</param>
     /// <param name="cancellationToken">Cancellation token for the read operation.</param>
     /// <param name="timeout">Optional per-call timeout override.</param>
     /// <param name="pathId">Optional path ID override; defaults to <see cref="PathId"/>.</param>
-    /// <returns>The per-spindle maximum RPMs, wrapped in a <see cref="FocasResult{T}"/>.</returns>
+    /// <returns>The per-spindle motor-speed meters, wrapped in a <see cref="FocasResult{T}"/>.</returns>
-    public Task<FocasResult<IReadOnlyList<WireSpindleMetric>>> ReadSpindleMaxRpmAsync(
+    public Task<FocasResult<IReadOnlyList<WireSpindleMetric>>> ReadSpindleMotorSpeedAsync(
         short spindleSelector = -1,
         CancellationToken cancellationToken = default,
         TimeSpan? timeout = null,
@@ -771,13 +780,27 @@ public sealed class FocasWireClient : IAsyncDisposable, IDisposable
             callTimeout.Token,
             new RequestBlock(0x0040, metric, spindleSelector, PathId: EffectivePathId(pathId))).ConfigureAwait(false);
 
-        return ToResult<IReadOnlyList<WireSpindleMetric>>(block, payload =>
+        return ToResult(block, ParseSpindleMetrics);
-        {
+    }
-            var values = new List<WireSpindleMetric>();
+
-            for (var offset = 0; offset + 8 <= payload.Length; offset += 8)
+    /// <summary>
-                values.Add(new WireSpindleMetric((short)(values.Count + 1), ReadInt32(payload, offset)));
+    ///     Decode a <c>cnc_rdspmeter</c> (0x0040) payload: 8-byte records of
-            return values;
+    ///     <c>[+0..3] i32 value</c>, <c>[+4..5] u16 base</c>, <c>[+6..7] u16 exponent</c>, one per
-        });
+    ///     slot of a fixed multi-slot buffer (slots past the spindle count are residue and decode
+    ///     as <see cref="WireSpindleMetric.IsValid"/> = false). Every slot is returned, in wire order.
+    /// </summary>
+    /// <param name="payload">The response-block payload.</param>
+    /// <returns>The per-slot meters.</returns>
+    internal static IReadOnlyList<WireSpindleMetric> ParseSpindleMetrics(byte[] payload)
+    {
+        var values = new List<WireSpindleMetric>();
+        for (var offset = 0; offset + 8 <= payload.Length; offset += 8)
+            values.Add(new WireSpindleMetric(
+                (short)(values.Count + 1),
+                ReadInt32(payload, offset),
+                BinaryPrimitives.ReadUInt16BigEndian(payload.AsSpan(offset + 4, 2)),
+                BinaryPrimitives.ReadUInt16BigEndian(payload.AsSpan(offset + 6, 2))));
+        return values;
     }
 
     private async Task<FocasResult<T>> ReadSingleAsync<T>(
@@ -958,18 +981,16 @@ public sealed class FocasWireClient : IAsyncDisposable, IDisposable
         payload.Length >= 8 ? BinaryPrimitives.ReadInt32LittleEndian(payload.AsSpan(4, 4)) : 0);
 
     /// <summary>
-    ///     Decode a <c>cnc_rdsvmeter</c> response into <see cref="WireServoMeter"/> records. On the
+    ///     Decode a <c>cnc_rdsvmeter</c> response into <see cref="WireServoMeter"/> records. Each
-    ///     31i-B (v3) each per-axis LOADELM is <b>8 bytes</b> — {int32 data; int16 dec; int16 unit}
+    ///     per-axis record is <b>8 bytes</b> — <c>[+0..3] i32 value</c>, <c>[+4..5] u16 base</c>,
-    ///     — NOT the 12-byte shape the original parser assumed. The 12-byte stride misaligned after
+    ///     <c>[+6..7] u16 exponent</c> — the same self-describing envelope as the position blocks,
-    ///     the first record (it read the dec/unit shorts of the prior record as the next record's
+    ///     so the load is <c>value / base^exponent</c>, a direct percentage. (A 12-byte stride
-    ///     data → wild values like 655360). Axis NAMES are not in the svmeter payload; they come
+    ///     misaligned after the first record; reading offset 4 as a decimal count divided every load
-    ///     from the <c>cnc_rdaxisname</c> (0x0089) block requested alongside it and are correlated
+    ///     by 10^10 — both fixed against live 31i-B captures, the latter by the sister ignitionoee
-    ///     by index. Validated against a live 31i-B 2026-06-25.
+    ///     driver, Focas.Wire-019.) Axis NAMES are not in the svmeter payload; they come from the
-    ///     <para><b>Scaling caveat:</b> downstream applies LoadPercent = data / 10^dec; on the 31i-B
+    ///     <c>cnc_rdaxisname</c> (0x0089) block requested alongside it and are correlated by index.
-    ///     <c>dec</c> read as 10, which makes idle loads vanishingly small. The data/dec/unit field
+    ///     The payload is a fixed 32-slot buffer: slots past the controlled-axis count are residue
-    ///     semantics for servo load are inferred from the wire and not yet confirmed against the
+    ///     and decode as <see cref="WireServoMeter.IsValid"/> = false.
-    ///     machine's servo-meter screen — confirm magnitude at commissioning. The alignment + name
-    ///     fix here is what removes the gross misaligned garbage.</para>
     /// </summary>
     /// <param name="svPayload">The raw <c>cnc_rdsvmeter</c> response payload.</param>
     /// <param name="axisNamePayload">The raw <c>cnc_rdaxisname</c> response payload used to correlate axis names by index.</param>
@@ -989,8 +1010,8 @@ public sealed class FocasWireClient : IAsyncDisposable, IDisposable
                 (short)(index + 1),
                 name,
                 ReadInt32(svPayload, offset),
-                ReadInt16(svPayload, offset + 4),
+                BinaryPrimitives.ReadUInt16BigEndian(svPayload.AsSpan(offset + 4, 2)),   // BASE, not a decimal
-                ReadInt16(svPayload, offset + 6)));
+                BinaryPrimitives.ReadUInt16BigEndian(svPayload.AsSpan(offset + 6, 2))));
         }
         return result;
     }

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.FOCAS/Wire/FocasWireModels.cs

@@ -59,18 +59,104 @@ public sealed record WireDynamic(
     int SpindleSpeed,
     WireAxisPosition Axis);
 
-/// <summary>One servo-meter entry from <c>cnc_rdsvmeter</c> — per-axis load percentage (scale by 10^<see cref="Decimal"/>).</summary>
+/// <summary>
+///     The self-describing <c>(value, base, exponent)</c> envelope shared by every value record on
+///     the FOCAS wire — <c>cnc_rddynamic2</c> positions, servo meters, spindle meters:
+///     <c>scaled = value / base^exponent</c>, where only base 2 and base 10 are meaningful.
+/// </summary>
+internal static class FocasValueEnvelope
+{
+    /// <summary>
+    ///     Largest exponent that can describe a real value. An i32 carries at most ten digits, so
+    ///     anything beyond is a misread record — and <c>value / 10^400</c> would be
+    ///     <c>value / Infinity = 0.0</c>, a plausible Good zero.
+    /// </summary>
+    public const int MaxExponent = 18;
+
+    /// <summary>
+    ///     True when the record describes a usable value. A fixed multi-slot buffer's slots past the
+    ///     configured axis/spindle count hold unrelated memory, which shows up exactly here: a base
+    ///     that is neither 2 nor 10, or an absurd exponent (incl. the <c>0xFFFF</c> vacant marker).
+    /// </summary>
+    /// <param name="base">The record's base field.</param>
+    /// <param name="exponent">The record's exponent field.</param>
+    /// <returns>Whether the record may be published.</returns>
+    public static bool IsValid(int @base, int exponent) => exponent <= MaxExponent && @base is 2 or 10;
+
+    /// <summary><c>value / base^exponent</c>, or null when <see cref="IsValid"/> is false.</summary>
+    /// <param name="value">The raw value.</param>
+    /// <param name="base">The record's base field.</param>
+    /// <param name="exponent">The record's exponent field.</param>
+    /// <returns>The scaled value, or null.</returns>
+    public static double? Scale(int value, int @base, int exponent) =>
+        !IsValid(@base, exponent) ? null : exponent == 0 ? value : value / Math.Pow(@base, exponent);
+}
+
+/// <summary>
+///     One servo-meter entry from <c>cnc_rdsvmeter</c> (0x0056): one axis's load. The 8-byte record
+///     is <c>[+0..3] i32 value</c>, <c>[+4..5] u16 base</c>, <c>[+6..7] u16 exponent</c> and the load
+///     is a <b>direct</b> percentage, <see cref="Scaled"/> = <c>value / base^exponent</c>.
+/// </summary>
+/// <remarks>
+///     Offset 4 used to be read as a decimal count ("data / 10^dec"). It is the <b>base</b> — a
+///     steady 10 — so every load was divided by 10^10 and published ~0 (a real Makino cutting at
+///     20,000 rpm read servo 0% on every axis). Found by the sister ignitionoee driver,
+///     Focas.Wire-019 (v0.17.2).
+/// </remarks>
+/// <param name="Index">1-based axis slot.</param>
+/// <param name="Name">Axis name from the companion 0x0089 block (empty when none).</param>
+/// <param name="Value">Raw load value.</param>
+/// <param name="Base">Scale base (2 or 10 when meaningful).</param>
+/// <param name="Exponent">Scale exponent.</param>
 public sealed record WireServoMeter(
     short Index,
     string Name,
     int Value,
-    short Decimal,
+    int Base,
-    short Unit);
+    int Exponent)
+{
+    /// <summary>False for a record whose envelope describes no usable value (buffer residue).</summary>
+    public bool IsValid => FocasValueEnvelope.IsValid(Base, Exponent);
 
-/// <summary>One spindle metric slot from <c>cnc_rdspload</c> / <c>cnc_rdspmaxrpm</c>.</summary>
+    /// <summary>The load percentage, <c>Value / Base^Exponent</c>; null when <see cref="IsValid"/> is false.</summary>
+    public double? Scaled => FocasValueEnvelope.Scale(Value, Base, Exponent);
+}
+
+/// <summary>
+///     One spindle-meter slot from <c>cnc_rdspmeter</c> (0x0040; type 0 = load, type 1 = motor
+///     speed). Same 8-byte envelope as <see cref="WireServoMeter"/>, but the scaled value is a
+///     fraction of full scale in <c>1/16384</c> units — see <see cref="Percent"/>.
+/// </summary>
+/// <param name="Index">1-based spindle slot.</param>
+/// <param name="Value">Raw meter value, in 1/16384-of-full-scale units.</param>
+/// <param name="Base">Scale base.</param>
+/// <param name="Exponent">Scale exponent.</param>
 public sealed record WireSpindleMetric(
     short Index,
-    int Value);
+    int Value,
+    int Base,
+    int Exponent)
+{
+    /// <summary>
+    ///     The meter's full-scale count: <c>16384</c> = 2^14 = 100% of rated load (type 0) or of
+    ///     maximum spindle speed (type 1). Settled on the real Z-34184 by regressing the type-1
+    ///     meter against <c>cnc_rddynamic2</c> spindle speed over 596–20,000 rpm:
+    ///     <c>rpm = 1.220749 × meter</c>, <c>16384 × 1.220749 = 20000.75</c> (Focas.Wire-019).
+    /// </summary>
+    public const int FullScale = 1 << 14;
+
+    /// <summary>False for a record whose envelope describes no usable value (buffer residue).</summary>
+    public bool IsValid => FocasValueEnvelope.IsValid(Base, Exponent);
+
+    /// <summary>
+    ///     The meter as a percentage — <c>(Value / Base^Exponent) × 100 / 16384</c> — or null when
+    ///     <see cref="IsValid"/> is false. Values above 100 are real (short-term overload; the i16
+    ///     record clamps one count short of 200%).
+    /// </summary>
+    public double? Percent => FocasValueEnvelope.Scale(Value, Base, Exponent) is { } scaled
+        ? scaled * 100.0 / FullScale
+        : null;
+}
 
 /// <summary>
 ///     One axis-name slot from <c>cnc_rdaxisname</c>. <see cref="Index"/> is the 1-based

src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.FOCAS/Wire/WireFocasClient.cs

@@ -242,34 +242,32 @@ public sealed class WireFocasClient : IFocasClient
         var result = await _wire.ReadServoMeterAsync(32, cancellationToken).ConfigureAwait(false);
         if (!result.IsOk || result.Value is null) return [];
         return result.Value
-            .Select(m => new FocasServoLoad(m.Name ?? string.Empty, m.Value / Math.Pow(10.0, m.Decimal)))
+            .Select(m => new FocasServoLoad(m.Name ?? string.Empty, m.Scaled))
             .Where(s => s.AxisName.Length > 0)
             .ToList();
     }
 
     /// <inheritdoc />
-    public Task<IReadOnlyList<int>> GetSpindleLoadsAsync(CancellationToken cancellationToken) =>
+    public Task<IReadOnlyList<double?>> GetSpindleLoadsAsync(CancellationToken cancellationToken) =>
         ReadSpindleMetricAsync((sel, ct) => _wire.ReadSpindleLoadAsync(sel, ct), cancellationToken);
 
     /// <inheritdoc />
-    public Task<IReadOnlyList<int>> GetSpindleMaxRpmsAsync(CancellationToken cancellationToken) =>
+    public Task<IReadOnlyList<double?>> GetSpindleMotorSpeedsAsync(CancellationToken cancellationToken) =>
-        ReadSpindleMetricAsync((sel, ct) => _wire.ReadSpindleMaxRpmAsync(sel, ct), cancellationToken);
+        ReadSpindleMetricAsync((sel, ct) => _wire.ReadSpindleMotorSpeedAsync(sel, ct), cancellationToken);
 
-    private static async Task<IReadOnlyList<int>> ReadSpindleMetricAsync(
+    /// <summary>
+    ///     One <c>cnc_rdspmeter</c> read as per-slot percentages (null for an undescribable slot).
+    ///     Every slot is returned — the driver reads only the slots of discovered spindles. (This
+    ///     used to stop at the first zero after slot 1, which both dropped a genuinely idle second
+    ///     spindle and kept non-zero buffer residue.)
+    /// </summary>
+    private static async Task<IReadOnlyList<double?>> ReadSpindleMetricAsync(
         Func<short, CancellationToken, Task<FocasResult<IReadOnlyList<WireSpindleMetric>>>> call,
         CancellationToken cancellationToken)
     {
         var result = await call(-1, cancellationToken).ConfigureAwait(false);
         if (!result.IsOk || result.Value is null) return [];
-        var list = new List<int>();
+        return result.Value.Select(m => m.Percent).ToList();
-        foreach (var m in result.Value)
-        {
-            // Fanuc pads unused spindle slots with 0 — stop at the first trailing zero so the
-            // list length matches the configured spindle count.
-            if (m.Value == 0 && list.Count > 0) break;
-            list.Add(m.Value);
-        }
-        return list;
     }
 
     /// <summary>Disposes the wire client and releases all resources.</summary>

tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.FOCAS.Tests/FakeFocasClient.cs

@@ -140,18 +140,18 @@ internal class FakeFocasClient : IFocasClient
     public virtual Task<IReadOnlyList<FocasServoLoad>> GetServoLoadsAsync(CancellationToken ct) =>
         Task.FromResult<IReadOnlyList<FocasServoLoad>>([.. ServoLoads]);
 
-    /// <summary>Gets the list of spindle loads.</summary>
+    /// <summary>Gets the list of spindle load percentages (null = undescribable slot).</summary>
-    public List<int> SpindleLoads { get; } = [];
+    public List<double?> SpindleLoads { get; } = [];
-    /// <summary>Gets the list of spindle maximum RPMs.</summary>
+    /// <summary>Gets the list of spindle motor-speed percentages (null = undescribable slot).</summary>
-    public List<int> SpindleMaxRpms { get; } = [];
+    public List<double?> SpindleMotorSpeeds { get; } = [];
     /// <summary>Gets spindle loads asynchronously.</summary>
     /// <param name="ct">The cancellation token.</param>
-    public virtual Task<IReadOnlyList<int>> GetSpindleLoadsAsync(CancellationToken ct) =>
+    public virtual Task<IReadOnlyList<double?>> GetSpindleLoadsAsync(CancellationToken ct) =>
-        Task.FromResult<IReadOnlyList<int>>([.. SpindleLoads]);
+        Task.FromResult<IReadOnlyList<double?>>([.. SpindleLoads]);
-    /// <summary>Gets spindle maximum RPMs asynchronously.</summary>
+    /// <summary>Gets spindle motor-speed percentages asynchronously.</summary>
     /// <param name="ct">The cancellation token.</param>
-    public virtual Task<IReadOnlyList<int>> GetSpindleMaxRpmsAsync(CancellationToken ct) =>
+    public virtual Task<IReadOnlyList<double?>> GetSpindleMotorSpeedsAsync(CancellationToken ct) =>
-        Task.FromResult<IReadOnlyList<int>>([.. SpindleMaxRpms]);
+        Task.FromResult<IReadOnlyList<double?>>([.. SpindleMotorSpeeds]);
 
     /// <summary>Disposes the client.</summary>
     public virtual void Dispose()

tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.FOCAS.Tests/FocasDuplicateSiblingNameTests.cs

@@ -34,8 +34,8 @@ public sealed class FocasDuplicateSiblingNameTests
             // Two spindles whose displays also collide, with distinct data per slot.
             c.SpindleNames.Clear();
             c.SpindleNames.AddRange([new("S", "1", "", ""), new("S", "1", "", "")]);
-            c.SpindleLoads.AddRange([5, 7]);
+            c.SpindleLoads.AddRange([5.0, 7.0]);
-            c.SpindleMaxRpms.AddRange([8_000, 12_000]);
+            c.SpindleMotorSpeeds.AddRange([40.0, 60.0]);
             return c;
         },
     };
@@ -159,17 +159,17 @@ public sealed class FocasDuplicateSiblingNameTests
         // The spindle read path matched by display name and took the FIRST index that matched,
         // so a duplicate spindle name made the second spindle's data unreachable.
         var drv = await StartedDriverAsync(
-            new FocasTagDefinition("raw/s1load", Host, "FIXED:Spindle/S1_1/Load", FocasDataType.Int32, Writable: false),
+            new FocasTagDefinition("raw/s1load", Host, "FIXED:Spindle/S1_1/Load", FocasDataType.Float64, Writable: false),
-            new FocasTagDefinition("raw/s2load", Host, "FIXED:Spindle/S1_2/Load", FocasDataType.Int32, Writable: false),
+            new FocasTagDefinition("raw/s2load", Host, "FIXED:Spindle/S1_2/Load", FocasDataType.Float64, Writable: false),
-            new FocasTagDefinition("raw/s1max", Host, "FIXED:Spindle/S1_1/MaxRpm", FocasDataType.Int32, Writable: false),
+            new FocasTagDefinition("raw/s1speed", Host, "FIXED:Spindle/S1_1/MotorSpeedPct", FocasDataType.Float64, Writable: false),
-            new FocasTagDefinition("raw/s2max", Host, "FIXED:Spindle/S1_2/MaxRpm", FocasDataType.Int32, Writable: false));
+            new FocasTagDefinition("raw/s2speed", Host, "FIXED:Spindle/S1_2/MotorSpeedPct", FocasDataType.Float64, Writable: false));
 
-        var read = await drv.ReadAsync(["raw/s1load", "raw/s2load", "raw/s1max", "raw/s2max"], CancellationToken.None);
+        var read = await drv.ReadAsync(["raw/s1load", "raw/s2load", "raw/s1speed", "raw/s2speed"], CancellationToken.None);
 
-        read[0].Value.ShouldBe(5);
+        read[0].Value.ShouldBe(5.0);
-        read[1].Value.ShouldBe(7);
+        read[1].Value.ShouldBe(7.0);
-        read[2].Value.ShouldBe(8_000);
+        read[2].Value.ShouldBe(40.0);
-        read[3].Value.ShouldBe(12_000);
+        read[3].Value.ShouldBe(60.0);
         read.ShouldAllBe(r => r.StatusCode == FocasStatusMapper.Good);
 
         await drv.ShutdownAsync(CancellationToken.None);

tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.FOCAS.Tests/FocasMeterDecodeTests.cs

@@ -0,0 +1,127 @@
+using System.Buffers.Binary;
+using Shouldly;
+using Xunit;
+using ZB.MOM.WW.OtOpcUa.Driver.FOCAS.Wire;
+
+namespace ZB.MOM.WW.OtOpcUa.Driver.FOCAS.Tests;
+
+/// <summary>
+///     Servo (<c>cnc_rdsvmeter</c>, 0x0056) and spindle (<c>cnc_rdspmeter</c>, 0x0040) meter decode.
+///     Both are arrays of 8-byte records carrying the same self-describing envelope as every other
+///     value block on this wire — <c>[+0..3] i32 value</c>, <c>[+4..5] u16 base</c> (2 or 10),
+///     <c>[+6..7] u16 exponent</c> — so <c>scaled = value / base^exponent</c>.
+///     Ported from the sister ignitionoee FOCAS driver v0.17.2 / v0.17.3 (Focas.Wire-019).
+/// </summary>
+/// <remarks>
+///     <para><b>Servo: offset 4 is the BASE, not a decimal count.</b> It holds a steady 10, so the
+///     old <c>value / 10^decimal</c> divided every load by 10^10 and published ~0 — on a real
+///     Makino cutting at 20,000 rpm the panel read servo 0% on every axis. Servo meters are
+///     <b>direct</b> percentages (the live capture shows −57..227).</para>
+///     <para><b>Spindle: a fraction of full scale in 1/16384 units.</b> Settled on the real Z-34184
+///     by regressing the type-1 meter against the independently read <c>cnc_rddynamic2</c> spindle
+///     speed over 596–20,000 rpm: <c>rpm = 1.220749 × meter</c>, and <c>16384 × 1.220749 =
+///     20000.75</c> — full scale is the spindle's 20,000 rpm maximum. So the type-1 meter
+///     (<c>cnc_rdspmaxrpm</c> by name) is the <b>motor speed as a % of maximum</b>, not a max-rpm
+///     constant; the type-0 load meter shares the envelope and the 16384 = 100% scale (its
+///     acceleration peaks pin at 32767 — one count short of a 200% overload).</para>
+/// </remarks>
+[Trait("Category", "Unit")]
+public sealed class FocasMeterDecodeTests
+{
+    private static byte[] Record(int value, int @base, int exponent)
+    {
+        var b = new byte[8];
+        BinaryPrimitives.WriteInt32BigEndian(b.AsSpan(0, 4), value);
+        BinaryPrimitives.WriteUInt16BigEndian(b.AsSpan(4, 2), (ushort)@base);
+        BinaryPrimitives.WriteUInt16BigEndian(b.AsSpan(6, 2), (ushort)exponent);
+        return b;
+    }
+
+    // ---- servo ----
+
+    [Fact]
+    public void The_live_servo_capture_reads_direct_percentages_not_value_over_ten_to_the_tenth()
+    {
+        var blocks = WireFixtures.Blocks("svmeter-pair-0x0056-0x0089.bin");
+        var meters = FocasWireClient.ParseServoMeters(
+            blocks.First(b => b.Command == 0x0056).Payload,
+            blocks.First(b => b.Command == 0x0089).Payload,
+            maxCount: 32);
+
+        meters[0].Base.ShouldBe(10);
+        meters[0].Exponent.ShouldBe(0);
+        meters.Take(3).Select(m => m.Scaled).ShouldBe([0.0, 50.0, -3.0]);
+    }
+
+    [Fact]
+    public void A_servo_record_applies_its_own_exponent()
+    {
+        var m = FocasWireClient.ParseServoMeters(Record(1234, 10, 1), Array.Empty<byte>(), 32).Single();
+        m.Scaled!.Value.ShouldBe(123.4, 1e-9);
+    }
+
+    [Theory]
+    [InlineData(5, 7, 0)]        // base neither 2 nor 10
+    [InlineData(5, 10, 2560)]    // residue past the controlled-axis count
+    public void An_undescribable_servo_record_has_no_value_not_zero(int value, int @base, int exponent)
+    {
+        var m = FocasWireClient.ParseServoMeters(Record(value, @base, exponent), Array.Empty<byte>(), 32).Single();
+        m.IsValid.ShouldBeFalse();
+        m.Scaled.ShouldBeNull();
+    }
+
+    // ---- spindle ----
+
+    [Fact]
+    public void The_live_spindle_load_capture_is_a_percentage_of_16384()
+    {
+        var metrics = FocasWireClient.ParseSpindleMetrics(
+            WireFixtures.Payload("live-spmeter-load-0x0040.bin", 0x0040));
+
+        // Slot 1: raw 0x23C3 = 9155, base 10, exponent 0 → 9155 × 100 / 16384 ≈ 55.88 %.
+        metrics[0].Value.ShouldBe(9155);
+        metrics[0].Percent!.Value.ShouldBe(9155 * 100.0 / 16384, 1e-9);
+        // Slot 2 is buffer residue (exponent 0x0A00 = 2560): no value, not a number.
+        metrics[1].IsValid.ShouldBeFalse();
+        metrics[1].Percent.ShouldBeNull();
+    }
+
+    [Fact]
+    public void The_live_motor_speed_capture_is_a_percentage_of_maximum_speed()
+    {
+        var metrics = FocasWireClient.ParseSpindleMetrics(
+            WireFixtures.Payload("live-spmeter-maxrpm-0x0040.bin", 0x0040));
+
+        // 0x3FFD = 16381 ≈ 99.98 % — a spindle at (just under) its 20,000 rpm maximum.
+        metrics[0].Value.ShouldBe(16381);
+        metrics[0].Percent!.Value.ShouldBe(16381 * 100.0 / 16384, 1e-9);
+    }
+
+    [Theory]
+    [InlineData(16382, 19998)]
+    [InlineData(12286, 14998)]
+    [InlineData(9830, 12000)]
+    [InlineData(695, 850)]
+    [InlineData(488, 595)]
+    public void Percent_reproduces_the_live_motor_speed_regression(int meter, int rpm)
+    {
+        var m = FocasWireClient.ParseSpindleMetrics(Record(meter, 10, 0)).Single();
+        m.Percent!.Value.ShouldBe(rpm * 100.0 / 20000.0, 0.02);
+    }
+
+    [Fact]
+    public void Full_scale_is_16384_and_overload_is_not_clamped()
+    {
+        WireSpindleMetric.FullScale.ShouldBe(16384);
+        FocasWireClient.ParseSpindleMetrics(Record(16384, 10, 0)).Single().Percent.ShouldBe(100.0);
+        var overload = FocasWireClient.ParseSpindleMetrics(Record(32767, 10, 0)).Single().Percent!.Value;
+        overload.ShouldBeInRange(199.9, 200.0);
+    }
+
+    [Fact]
+    public void The_spindle_envelope_exponent_applies_before_the_full_scale_division()
+    {
+        // 163840 / 10^1 = 16384 counts = 100 %.
+        FocasWireClient.ParseSpindleMetrics(Record(163840, 10, 1)).Single().Percent!.Value.ShouldBe(100.0, 1e-9);
+    }
+}

tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.FOCAS.Tests/FocasMeterPublishTests.cs

@@ -0,0 +1,134 @@
+using Shouldly;
+using Xunit;
+using ZB.MOM.WW.OtOpcUa.Core.Abstractions;
+using ZB.MOM.WW.OtOpcUa.Driver.FOCAS;
+
+namespace ZB.MOM.WW.OtOpcUa.Driver.FOCAS.Tests;
+
+/// <summary>
+///     Driver-level publish of servo / spindle meters (Focas.Wire-019 port): percentages publish
+///     Good as Float64, an undescribable record publishes BadNoData (never a Good 0), and the
+///     spindle motor-speed meter is a live, polled <c>MotorSpeedPct</c> — not the bootstrap-time
+///     <c>MaxRpm</c> constant it was mislabelled as.
+/// </summary>
+[Trait("Category", "Unit")]
+public sealed class FocasMeterPublishTests
+{
+    private const string Host = "focas://10.0.0.5:8193";
+
+    private static FocasDriver NewDriver(FakeFocasClient client) =>
+        new(new FocasDriverOptions
+        {
+            Devices = [new FocasDeviceOptions(Host)],
+            Probe = new FocasProbeOptions { Enabled = false },
+            FixedTree = new FocasFixedTreeOptions { Enabled = true, PollInterval = TimeSpan.FromMilliseconds(10) },
+        }, "drv-1", new FakeFocasClientFactory { Customise = () => client });
+
+    private static async Task<DataValueSnapshot> ReadSettledAsync(FocasDriver drv, string reference, Func<DataValueSnapshot, bool> settled)
+    {
+        var deadline = DateTime.UtcNow + TimeSpan.FromSeconds(5);
+        DataValueSnapshot last;
+        do
+        {
+            last = (await drv.ReadAsync([reference], CancellationToken.None)).Single();
+            if (settled(last)) return last;
+            await Task.Delay(15);
+        } while (DateTime.UtcNow < deadline);
+        return last;
+    }
+
+    private static FakeFocasClient MachineClient()
+    {
+        var c = new FakeFocasClient();
+        c.AxisNames.Clear();
+        c.AxisNames.AddRange([new("X", ""), new("Y", "")]);
+        c.ServoLoads.AddRange([new("X", 46.0), new("Y", null)]); // Y: undescribable record
+        c.SpindleNames.Clear();
+        c.SpindleNames.Add(new("S", "1", "", ""));
+        c.SpindleLoads.Add(55.88);
+        c.SpindleMotorSpeeds.Add(2.49);
+        return c;
+    }
+
+    [Fact]
+    public async Task Servo_loads_publish_percentages_and_an_undescribable_record_is_bad()
+    {
+        var drv = NewDriver(MachineClient());
+        await drv.InitializeAsync("{}", CancellationToken.None);
+
+        var x = await ReadSettledAsync(drv, $"{Host}/Axes/X/ServoLoad", s => s.StatusCode == FocasStatusMapper.Good);
+        var y = await ReadSettledAsync(drv, $"{Host}/Axes/Y/ServoLoad", s => s.StatusCode == FocasStatusMapper.BadNoData);
+
+        x.Value.ShouldBe(46.0);
+        y.StatusCode.ShouldBe(FocasStatusMapper.BadNoData);
+        y.Value.ShouldBeNull();
+        await drv.ShutdownAsync(CancellationToken.None);
+    }
+
+    [Fact]
+    public async Task Spindle_meters_publish_float64_percentages_and_motor_speed_is_polled_live()
+    {
+        var client = MachineClient();
+        var drv = NewDriver(client);
+        await drv.InitializeAsync("{}", CancellationToken.None);
+
+        var load = await ReadSettledAsync(drv, $"{Host}/Spindle/S1/Load", s => s.StatusCode == FocasStatusMapper.Good);
+        load.Value.ShouldBe(55.88);
+        (await ReadSettledAsync(drv, $"{Host}/Spindle/S1/MotorSpeedPct", s => s.StatusCode == FocasStatusMapper.Good))
+            .Value.ShouldBe(2.49);
+
+        // The spindle speeds up: the poll loop must follow it (MaxRpm was read once at bootstrap).
+        client.SpindleMotorSpeeds[0] = 99.98;
+        (await ReadSettledAsync(drv, $"{Host}/Spindle/S1/MotorSpeedPct", s => Equals(s.Value, 99.98)))
+            .Value.ShouldBe(99.98);
+        await drv.ShutdownAsync(CancellationToken.None);
+    }
+
+    [Fact]
+    public async Task An_undescribable_spindle_slot_is_bad_not_zero()
+    {
+        var client = MachineClient();
+        client.SpindleLoads[0] = null;
+        var drv = NewDriver(client);
+        await drv.InitializeAsync("{}", CancellationToken.None);
+
+        var load = await ReadSettledAsync(drv, $"{Host}/Spindle/S1/Load", s => s.StatusCode == FocasStatusMapper.BadNoData);
+
+        load.StatusCode.ShouldBe(FocasStatusMapper.BadNoData);
+        load.Value.ShouldBeNull();
+        await drv.ShutdownAsync(CancellationToken.None);
+    }
+
+    [Fact]
+    public async Task The_spindle_folder_offers_MotorSpeedPct_not_MaxRpm()
+    {
+        var drv = NewDriver(MachineClient());
+        await drv.InitializeAsync("{}", CancellationToken.None);
+        await ReadSettledAsync(drv, $"{Host}/Spindle/S1/Load", s => s.StatusCode == FocasStatusMapper.Good);
+
+        var builder = new NameRecordingBuilder();
+        await drv.DiscoverAsync(builder, CancellationToken.None);
+
+        builder.Variables.ShouldContain("MotorSpeedPct");
+        builder.Variables.ShouldNotContain("MaxRpm");
+        await drv.ShutdownAsync(CancellationToken.None);
+    }
+
+    private sealed class NameRecordingBuilder : IAddressSpaceBuilder
+    {
+        public List<string> Variables { get; } = [];
+        public IAddressSpaceBuilder Folder(string browseName, string displayName) => this;
+        public IVariableHandle Variable(string browseName, string displayName, DriverAttributeInfo attributeInfo)
+        {
+            Variables.Add(browseName);
+            return new Handle(attributeInfo.FullName);
+        }
+        public void AddProperty(string browseName, DriverDataType dataType, object? value) { }
+
+        private sealed class Handle(string fullRef) : IVariableHandle
+        {
+            public string FullReference => fullRef;
+            public IAlarmConditionSink MarkAsAlarmCondition(AlarmConditionInfo info) => throw new NotSupportedException();
+        }
+    }
+}

tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.FOCAS.Tests/FocasWireV3Tests.cs

@@ -98,7 +98,7 @@ public sealed class FocasWireV3Tests
     [Fact]
     public void ParseServoMeters_uses_an_eight_byte_stride_and_names_from_the_axis_block()
     {
-        // Three 8-byte records {int32 data; int16 dec=10; int16 unit=0}: data = 0, 50, -3.
+        // Three 8-byte records {int32 value; u16 base=10; u16 exponent=0}: value = 0, 50, -3.
         byte[] sv =
         [
             0x00, 0x00, 0x00, 0x00, 0x00, 0x0a, 0x00, 0x00, // axis 1: data=0
@@ -120,7 +120,8 @@ public sealed class FocasWireV3Tests
         meters[0].Value.ShouldBe(0);
         meters[1].Name.ShouldBe("Y");
         meters[1].Value.ShouldBe(50);   // 8-byte stride: a 12-byte stride would misread this as 655360
-        meters[1].Decimal.ShouldBe((short)10);
+        meters[1].Base.ShouldBe(10);       // offset 4 is the envelope BASE, not a decimal count
+        meters[1].Scaled.ShouldBe(50.0);
         meters[2].Name.ShouldBe("Z");
         meters[2].Value.ShouldBe(-3);
     }