Auto: ablegacy-1 — PLC-5 octal I/O addressing

Closes #244

src/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy/AbLegacyAddress.cs

@@ -1,3 +1,5 @@
+using ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.PlcFamilies;
+
 namespace ZB.MOM.WW.OtOpcUa.Driver.AbLegacy;
 
 /// <summary>
@@ -41,21 +43,38 @@ public sealed record AbLegacyAddress(
         return wordPart;
     }
 
-    public static AbLegacyAddress? TryParse(string? value)
+    public static AbLegacyAddress? TryParse(string? value) => TryParse(value, family: null);
+
+    /// <summary>
+    ///     Family-aware parser. PLC-5 (RSLogix 5) displays the word + bit indices on
+    ///     <c>I:</c>/<c>O:</c> file references as octal — <c>I:001/17</c> is rack 1, bit 15.
+    ///     Pass the device's family so the parser can interpret those digits as octal when the
+    ///     family's <see cref="AbLegacyPlcFamilyProfile.OctalIoAddressing"/> is true. The parsed
+    ///     record stores decimal values; <see cref="ToLibplctagName"/> emits decimal too, which
+    ///     is what libplctag's PCCC layer expects.
+    /// </summary>
+    public static AbLegacyAddress? TryParse(string? value, AbLegacyPlcFamily? family)
     {
         if (string.IsNullOrWhiteSpace(value)) return null;
         var src = value.Trim();
 
-        // BitIndex: trailing /N
+        var profile = family is null ? null : AbLegacyPlcFamilyProfile.ForFamily(family.Value);
-        int? bitIndex = null;
+
+        // BitIndex: trailing /N. Defer numeric parsing until the file letter is known — PLC-5
+        // I:/O: bit indices are octal in RSLogix 5, everything else is decimal.
+        string? bitText = null;
         var slashIdx = src.IndexOf('/');
         if (slashIdx >= 0)
         {
-            if (!int.TryParse(src[(slashIdx + 1)..], out var bit) || bit < 0 || bit > 31) return null;
+            bitText = src[(slashIdx + 1)..];
-            bitIndex = bit;
             src = src[..slashIdx];
         }
 
+        return ParseTail(src, bitText, profile);
+    }
+
+    private static AbLegacyAddress? ParseTail(string src, string? bitText, AbLegacyPlcFamilyProfile? profile)
+    {
         // SubElement: trailing .NAME (ACC / PRE / EN / DN / TT / CU / CD / FD / etc.)
         string? subElement = null;
         var dotIdx = src.LastIndexOf('.');
@@ -73,7 +92,6 @@ public sealed record AbLegacyAddress(
         if (colonIdx <= 0) return null;
         var filePart = src[..colonIdx];
         var wordPart = src[(colonIdx + 1)..];
-        if (!int.TryParse(wordPart, out var word) || word < 0) return null;
 
         // File letter + optional file number (single letter for I/O/S, letter+number otherwise).
         if (filePart.Length == 0 || !char.IsLetter(filePart[0])) return null;
@@ -91,9 +109,43 @@ public sealed record AbLegacyAddress(
         // Reject unknown file letters — these cover SLC/ML/PLC-5 canonical families.
         if (!IsKnownFileLetter(letter)) return null;
 
+        var octalForIo = profile?.OctalIoAddressing == true && (letter == "I" || letter == "O");
+
+        if (!TryParseIndex(wordPart, octalForIo, out var word) || word < 0) return null;
+
+        int? bitIndex = null;
+        if (bitText is not null)
+        {
+            if (!TryParseIndex(bitText, octalForIo, out var bit) || bit < 0 || bit > 31) return null;
+            bitIndex = bit;
+        }
+
         return new AbLegacyAddress(letter, fileNumber, word, bitIndex, subElement);
     }
 
+    private static bool TryParseIndex(string text, bool octal, out int value)
+    {
+        if (octal)
+        {
+            // Octal accepts only digits 0-7. Reject 8/9 explicitly.
+            if (text.Length == 0) { value = 0; return false; }
+            var start = 0;
+            var sign = 1;
+            if (text[0] == '-') { sign = -1; start = 1; }
+            if (start >= text.Length) { value = 0; return false; }
+            var acc = 0;
+            for (var i = start; i < text.Length; i++)
+            {
+                var c = text[i];
+                if (c < '0' || c > '7') { value = 0; return false; }
+                acc = (acc * 8) + (c - '0');
+            }
+            value = sign * acc;
+            return true;
+        }
+        return int.TryParse(text, out value);
+    }
+
     private static bool IsKnownFileLetter(string letter) => letter switch
     {
         "N" or "F" or "B" or "L" or "ST" or "T" or "C" or "R" or "I" or "O" or "S" or "A" => true,

src/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy/AbLegacyDriver.cs

@@ -140,7 +140,7 @@ public sealed class AbLegacyDriver : IDriver, IReadable, IWritable, ITagDiscover
                     continue;
                 }
 
-                var parsed = AbLegacyAddress.TryParse(def.Address);
+                var parsed = AbLegacyAddress.TryParse(def.Address, device.Options.PlcFamily);
                 var value = runtime.DecodeValue(def.DataType, parsed?.BitIndex);
                 results[i] = new DataValueSnapshot(value, AbLegacyStatusMapper.Good, now, now);
                 _health = new DriverHealth(DriverState.Healthy, now, null);
@@ -186,7 +186,7 @@ public sealed class AbLegacyDriver : IDriver, IReadable, IWritable, ITagDiscover
 
             try
             {
-                var parsed = AbLegacyAddress.TryParse(def.Address);
+                var parsed = AbLegacyAddress.TryParse(def.Address, device.Options.PlcFamily);
 
                 // PCCC bit-within-word writes — task #181 pass 2. RMW against a parallel
                 // parent-word runtime (strip the /N bit suffix). Per-parent-word lock serialises
@@ -413,7 +413,7 @@ public sealed class AbLegacyDriver : IDriver, IReadable, IWritable, ITagDiscover
     {
         if (device.Runtimes.TryGetValue(def.Name, out var existing)) return existing;
 
-        var parsed = AbLegacyAddress.TryParse(def.Address)
+        var parsed = AbLegacyAddress.TryParse(def.Address, device.Options.PlcFamily)
             ?? throw new InvalidOperationException(
                 $"AbLegacy tag '{def.Name}' has malformed Address '{def.Address}'.");
 

src/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy/AbLegacyDriverOptions.cs

@@ -23,7 +23,7 @@ public sealed record AbLegacyDeviceOptions(
 
 /// <summary>
 ///     One PCCC-backed OPC UA variable. <paramref name="Address"/> is the canonical PCCC
-///     file-address string that parses via <see cref="AbLegacyAddress.TryParse"/>.
+///     file-address string that parses via <see cref="AbLegacyAddress.TryParse(string?)"/>.
 /// </summary>
 public sealed record AbLegacyTagDefinition(
     string Name,

src/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy/PlcFamilies/AbLegacyPlcFamilyProfile.cs

@@ -9,7 +9,8 @@ public sealed record AbLegacyPlcFamilyProfile(
     string DefaultCipPath,
     int MaxTagBytes,
     bool SupportsStringFile,
-    bool SupportsLongFile)
+    bool SupportsLongFile,
+    bool OctalIoAddressing)
 {
     public static AbLegacyPlcFamilyProfile ForFamily(AbLegacyPlcFamily family) => family switch
     {
@@ -25,21 +26,24 @@ public sealed record AbLegacyPlcFamilyProfile(
         DefaultCipPath: "1,0",
         MaxTagBytes: 240,           // SLC 5/05 PCCC max packet data
         SupportsStringFile: true,   // ST file available SLC 5/04+
-        SupportsLongFile: true);    // L file available SLC 5/05+
+        SupportsLongFile: true,     // L file available SLC 5/05+
+        OctalIoAddressing: false);  // SLC500 I:/O: indices are decimal in RSLogix 500
 
     public static readonly AbLegacyPlcFamilyProfile MicroLogix = new(
         LibplctagPlcAttribute: "micrologix",
         DefaultCipPath: "",         // MicroLogix 1100/1400 use direct EIP, no backplane path
         MaxTagBytes: 232,
         SupportsStringFile: true,
-        SupportsLongFile: false);   // ML 1100/1200/1400 don't ship L files
+        SupportsLongFile: false,    // ML 1100/1200/1400 don't ship L files
+        OctalIoAddressing: false);  // MicroLogix follows SLC-style decimal I/O addressing
 
     public static readonly AbLegacyPlcFamilyProfile Plc5 = new(
         LibplctagPlcAttribute: "plc5",
         DefaultCipPath: "1,0",
         MaxTagBytes: 240,           // DF1 full-duplex packet limit at 264 bytes, PCCC-over-EIP caps lower
         SupportsStringFile: true,
-        SupportsLongFile: false);   // PLC-5 predates L files
+        SupportsLongFile: false,    // PLC-5 predates L files
+        OctalIoAddressing: true);   // RSLogix 5 displays I:/O: word + bit indices as octal
 
     /// <summary>
     ///     Logix ControlLogix / CompactLogix accessed through the legacy PCCC compatibility layer.
@@ -51,7 +55,8 @@ public sealed record AbLegacyPlcFamilyProfile(
         DefaultCipPath: "1,0",
         MaxTagBytes: 240,
         SupportsStringFile: true,
-        SupportsLongFile: true);
+        SupportsLongFile: true,
+        OctalIoAddressing: false);  // Logix natively uses decimal arrays even via the PCCC bridge
 }
 
 /// <summary>Which PCCC PLC family the device is.</summary>

tests/ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.Tests/AbLegacyAddressTests.cs

@@ -1,6 +1,7 @@
 using Shouldly;
 using Xunit;
 using ZB.MOM.WW.OtOpcUa.Driver.AbLegacy;
+using ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.PlcFamilies;
 
 namespace ZB.MOM.WW.OtOpcUa.Driver.AbLegacy.Tests;
 
@@ -65,4 +66,77 @@ public sealed class AbLegacyAddressTests
         a.ShouldNotBeNull();
         a.ToLibplctagName().ShouldBe(input);
     }
+
+    // ---- PLC-5 octal I:/O: addressing (Issue #244) ----
+    //
+    // RSLogix 5 displays I:/O: word + bit indices as octal. `I:001/17` means rack 1, bit 15
+    // (octal 17). Other PCCC families (SLC500, MicroLogix, LogixPccc) keep decimal indices.
+    // Non-I/O file letters are always decimal regardless of family.
+
+    [Theory]
+    [InlineData("I:001/17", 1, 15)]   // octal 17 → bit 15
+    [InlineData("I:0/0", 0, 0)]       // boundary: octal 0
+    [InlineData("O:1/2", 1, 2)]       // octal 1, 2 happen to match decimal
+    [InlineData("I:010/10", 8, 8)]    // octal 10 → 8 (both word + bit)
+    [InlineData("I:007/7", 7, 7)]     // boundary: largest single octal digit
+    public void TryParse_Plc5_parses_io_indices_as_octal(string input, int expectedWord, int expectedBit)
+    {
+        var a = AbLegacyAddress.TryParse(input, AbLegacyPlcFamily.Plc5);
+        a.ShouldNotBeNull();
+        a.WordNumber.ShouldBe(expectedWord);
+        a.BitIndex.ShouldBe(expectedBit);
+    }
+
+    [Theory]
+    [InlineData("I:8/0")]    // word digit 8 illegal in octal
+    [InlineData("I:0/9")]    // bit digit 9 illegal in octal
+    [InlineData("O:128/0")]  // contains digit 8
+    [InlineData("I:0/18")]   // bit field octal-illegal because of '8'
+    public void TryParse_Plc5_rejects_octal_invalid_io_digits(string input)
+    {
+        AbLegacyAddress.TryParse(input, AbLegacyPlcFamily.Plc5).ShouldBeNull();
+    }
+
+    [Theory]
+    // Non-I/O files stay decimal even on PLC-5 (e.g. N7:8 is integer 7, word 8).
+    [InlineData("N7:8", 7, 8)]
+    [InlineData("F8:9", 8, 9)]
+    public void TryParse_Plc5_keeps_non_io_indices_decimal(string input, int? expectedFile, int expectedWord)
+    {
+        var a = AbLegacyAddress.TryParse(input, AbLegacyPlcFamily.Plc5);
+        a.ShouldNotBeNull();
+        a.FileNumber.ShouldBe(expectedFile);
+        a.WordNumber.ShouldBe(expectedWord);
+    }
+
+    [Fact]
+    public void TryParse_Slc500_keeps_io_indices_decimal_back_compat()
+    {
+        // SLC500 has OctalIoAddressing=false — the digits are decimal as before.
+        var a = AbLegacyAddress.TryParse("I:10/15", AbLegacyPlcFamily.Slc500);
+        a.ShouldNotBeNull();
+        a.WordNumber.ShouldBe(10);
+        a.BitIndex.ShouldBe(15);
+
+        // Decimal '8' that PLC-5 would reject is fine on SLC500.
+        var b = AbLegacyAddress.TryParse("I:8/0", AbLegacyPlcFamily.Slc500);
+        b.ShouldNotBeNull();
+        b.WordNumber.ShouldBe(8);
+    }
+
+    [Fact]
+    public void TryParse_MicroLogix_and_LogixPccc_keep_io_indices_decimal()
+    {
+        AbLegacyAddress.TryParse("I:9/0", AbLegacyPlcFamily.MicroLogix).ShouldNotBeNull();
+        AbLegacyAddress.TryParse("I:9/0", AbLegacyPlcFamily.LogixPccc).ShouldNotBeNull();
+    }
+
+    [Fact]
+    public void Plc5Profile_advertises_octal_io_addressing()
+    {
+        AbLegacyPlcFamilyProfile.Plc5.OctalIoAddressing.ShouldBeTrue();
+        AbLegacyPlcFamilyProfile.Slc500.OctalIoAddressing.ShouldBeFalse();
+        AbLegacyPlcFamilyProfile.MicroLogix.OctalIoAddressing.ShouldBeFalse();
+        AbLegacyPlcFamilyProfile.LogixPccc.OctalIoAddressing.ShouldBeFalse();
+    }
 }