feat(twincat): array and STRING writes through the codecs (U9)
Array tags were advertised writable but every write threw InvalidCastException in ConvertForWrite (reported BadTypeMismatch); STRING writes went through the Beckhoff marshaller with no length check against STRING(n) and the host's ANSI code page, which the read side deliberately avoids. - Array write: TwinCATArrayCodec.ToWriteElements converts exactly ArrayLength elements to the declared type (CLR lists convert - ScadaBridge writes int[] to Int16 nodes; a length mismatch or out-of-range element is BadOutOfRange, a scalar value BadTypeMismatch) before any wire traffic; the ADS client plans the layout from the resolved PLC array (TwinCATTypeGuard.CheckArray, as the read does), encodes with TwinCATArrayCodec.Encode - the exact inverse of Decode - and writes the raw bytes (new ITwinCATClient.WriteArrayAsync). - STRING / WSTRING write: encoded at the PLC's declared width by TwinCATStringCodec.EncodeString/EncodeWString (Windows-1252 or UTF-8 per target, NUL-padded, strict: an over-long value or unrepresentable character is OverflowException -> BadOutOfRange) and written as raw bytes. - TwinCAT CLI read/write gain --array-length (+ --separator) for the hardware gate. Refs #739 Claude-Session: https://claude.ai/code/session_01Ub9hGmYLQvn9XETzw7CMsT
This commit is contained in:
Joseph Doherty
@@ -19,6 +19,84 @@ namespace ZB.MOM.WW.OtOpcUa.Driver.TwinCAT;
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/// </remarks>
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internal static class TwinCATArrayCodec
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{
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/// <summary>
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/// Converts a client-supplied array value into exactly <paramref name="count"/> elements of the
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/// declared type, each converted the way a scalar write converts (<see cref="AdsTwinCATClient.ConvertForWrite"/>
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/// — so TIME/DATE elements become their encoded <c>uint</c>). Any CLR collection is accepted and the
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/// element type is CONVERTED, not exact-matched: ScadaBridge writes an <c>int[]</c> to an Int16 node.
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/// </summary>
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/// <param name="declared">The tag's declared element type.</param>
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/// <param name="value">The written value — an array or list.</param>
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/// <param name="count">The tag's authored <c>ArrayLength</c>.</param>
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/// <returns>The converted elements, in order.</returns>
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/// <exception cref="InvalidCastException">The value is not a collection (a scalar, a string, null), or
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/// an element cannot convert.</exception>
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/// <exception cref="OverflowException">The element count differs from <paramref name="count"/>, or an
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/// element is outside the declared type's range.</exception>
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public static object[] ToWriteElements(TwinCATDataType declared, object? value, int count)
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{
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if (value is null or string || value is not System.Collections.IEnumerable items)
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throw new InvalidCastException(
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$"an array tag of {count} {declared} takes an array value, not {value?.GetType().Name ?? "null"}");
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var elements = new List<object>(count);
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foreach (var item in items) elements.Add(AdsTwinCATClient.ConvertForWrite(declared, item));
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if (elements.Count != count)
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throw new OverflowException($"wrote {elements.Count} elements to an array tag of arrayLength {count}");
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return [.. elements];
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}
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/// <summary>
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/// Encodes converted elements (<see cref="ToWriteElements"/>) into the PLC's raw bytes at the planned
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/// layout — the exact inverse of <see cref="Decode"/>: little-endian at the element stride, a
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/// STRING / WSTRING element encoded by <see cref="TwinCATStringCodec"/> within its fixed stride.
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/// </summary>
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/// <param name="declared">The tag's declared element type.</param>
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/// <param name="elements">The converted elements; exactly <see cref="TwinCATArrayLayout.ElementCount"/>.</param>
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/// <param name="layout">The layout planned from the PLC array (<see cref="TwinCATTypeGuard.CheckArray"/>).</param>
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/// <param name="utf8">True when the target reports UTF-8 STRING data (else Windows-1252).</param>
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/// <returns>Exactly <see cref="TwinCATArrayLayout.ByteLength"/> bytes.</returns>
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/// <exception cref="ArgumentException">The element count differs from the layout.</exception>
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/// <exception cref="OverflowException">A string element does not fit its stride.</exception>
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public static byte[] Encode(TwinCATDataType declared, IReadOnlyList<object> elements, TwinCATArrayLayout layout, bool utf8)
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{
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if (layout.Stride <= 0 || elements.Count != layout.ElementCount)
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throw new ArgumentException(
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$"{elements.Count} elements do not match a layout of {layout.ElementCount} × {layout.Stride} B", nameof(elements));
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var bytes = new byte[layout.ByteLength];
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var stride = layout.Stride;
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for (var i = 0; i < elements.Count; i++)
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{
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var slot = bytes.AsSpan(i * stride, stride);
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var e = elements[i];
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switch (declared)
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{
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case TwinCATDataType.Bool: slot[0] = Convert.ToBoolean(e) ? (byte)1 : (byte)0; break;
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case TwinCATDataType.SInt: slot[0] = unchecked((byte)Convert.ToSByte(e)); break;
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case TwinCATDataType.USInt: slot[0] = Convert.ToByte(e); break;
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case TwinCATDataType.Int: BinaryPrimitives.WriteInt16LittleEndian(slot, Convert.ToInt16(e)); break;
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case TwinCATDataType.UInt: BinaryPrimitives.WriteUInt16LittleEndian(slot, Convert.ToUInt16(e)); break;
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case TwinCATDataType.DInt: BinaryPrimitives.WriteInt32LittleEndian(slot, Convert.ToInt32(e)); break;
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case TwinCATDataType.UDInt or TwinCATDataType.Time or TwinCATDataType.TimeOfDay
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or TwinCATDataType.Date or TwinCATDataType.DateTime:
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BinaryPrimitives.WriteUInt32LittleEndian(slot, Convert.ToUInt32(e)); break;
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case TwinCATDataType.LInt: BinaryPrimitives.WriteInt64LittleEndian(slot, Convert.ToInt64(e)); break;
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case TwinCATDataType.ULInt: BinaryPrimitives.WriteUInt64LittleEndian(slot, Convert.ToUInt64(e)); break;
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case TwinCATDataType.Real: BinaryPrimitives.WriteSingleLittleEndian(slot, Convert.ToSingle(e)); break;
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case TwinCATDataType.LReal: BinaryPrimitives.WriteDoubleLittleEndian(slot, Convert.ToDouble(e)); break;
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case TwinCATDataType.String:
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TwinCATStringCodec.EncodeString(Convert.ToString(e) ?? string.Empty, stride, utf8).CopyTo(slot);
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break;
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case TwinCATDataType.WString:
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TwinCATStringCodec.EncodeWString(Convert.ToString(e) ?? string.Empty, stride).CopyTo(slot);
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break;
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default:
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throw new NotSupportedException($"TwinCATDataType {declared} has no array element encoding");
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}
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}
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return bytes;
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}
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/// <summary>Decodes <paramref name="layout"/>.ElementCount elements of <paramref name="declared"/>.</summary>
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/// <param name="declared">The tag's declared element type.</param>
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/// <param name="bytes">The PLC bytes from the array's first element (at least <see cref="TwinCATArrayLayout.ByteLength"/>).</param>
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