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fix(s7): treat ArrayCount>=1 as array so 1-element arrays read as arrays (review I-2)

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This commit is contained in:
Joseph Doherty
2026-06-16 22:12:30 -04:00
parent 49ac1392a8
commit 3bbe39c166
2 changed files with 46 additions and 11 deletions
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src/Drivers/ZB.MOM.WW.OtOpcUa.Driver.S7/S7Driver.cs
+8 -7
View File
@@ -442,11 +442,12 @@ public sealed class S7Driver
? parsed
: S7AddressParser.Parse(tag.Address);
// Array path: a tag with a declared count > 1 reads a CONTIGUOUS block of
// Array path: a tag with a declared count >= 1 reads a CONTIGUOUS block of
// count × element-bytes in a SINGLE round-trip (Plc.ReadBytesAsync), then decodes each
// element from its big-endian slice into an element-typed CLR array. The scalar path
// (count null / <= 1) is left byte-for-byte unchanged below.
if (tag.ArrayCount is > 1)
// (count null) is left byte-for-byte unchanged below. A count of 1 IS a valid 1-element
// array (the foundation materialises a [1] OPC UA array node when isArray:true).
if (tag.ArrayCount is >= 1)
return await ReadArrayAsync(plc, tag, addr, ct).ConfigureAwait(false);
// S7.Net's string-based ReadAsync returns object where the boxed .NET type depends on
@@ -793,10 +794,10 @@ public sealed class S7Driver
var folder = builder.Folder("S7", "S7");
foreach (var t in _options.Tags)
{
// A tag carrying an array count (> 1) surfaces as a 1-D OPC UA array node; a missing
// count or a count of 1 stays scalar (count == 1 array adds no information over a
// scalar and would force every read down the slower block path).
var isArray = t.ArrayCount is > 1;
// A tag carrying a non-null array count (>= 1) surfaces as a 1-D OPC UA array node.
// A null count stays scalar. A count of 1 IS a valid 1-element array: the foundation
// materialises a [1] OPC UA array node when isArray:true, so the driver must agree.
var isArray = t.ArrayCount is >= 1;
folder.Variable(t.Name, t.Name, new DriverAttributeInfo(
FullName: t.Name,
DriverDataType: MapDataType(t.DataType),
tests/Drivers/ZB.MOM.WW.OtOpcUa.Driver.S7.Tests/S7ArrayReadTests.cs
+38 -4
View File
@@ -216,9 +216,11 @@ public sealed class S7ArrayReadTests
arr.ArrayDim.ShouldBe(8u);
}
/// <summary>Verifies a tag with ArrayCount of 1 is treated as a scalar (no array node).</summary>
/// <summary>Verifies a tag with ArrayCount of 1 is treated as a 1-element array (not scalar).
/// The foundation materialises a [1] OPC UA array node when IsArray=true, so the driver must
/// honour isArray:true + arrayLength:1 — a 1-element array IS a valid array.</summary>
[Fact]
public async Task DiscoverAsync_count_of_one_is_scalar()
public async Task DiscoverAsync_count_of_one_is_array()
{
var opts = new S7DriverOptions
{
@@ -231,8 +233,40 @@ public sealed class S7ArrayReadTests
await drv.DiscoverAsync(builder, TestContext.Current.CancellationToken);
var one = builder.Variables.Single().Attr;
one.IsArray.ShouldBeFalse("count<=1 is scalar");
one.ArrayDim.ShouldBeNull();
one.IsArray.ShouldBeTrue("ArrayCount=1 is a 1-element array, not scalar");
one.ArrayDim.ShouldBe(1u);
}
/// <summary>Verifies that a tag with a null ArrayCount (scalar) is still discovered as scalar.</summary>
[Fact]
public async Task DiscoverAsync_null_ArrayCount_is_scalar()
{
var opts = new S7DriverOptions
{
Host = "192.0.2.1",
Tags = [new("Scalar", "DB1.DBW0", S7DataType.Int16, ArrayCount: null)],
};
using var drv = new S7Driver(opts, "s7-arr-null");
var builder = new RecordingBuilder();
await drv.DiscoverAsync(builder, TestContext.Current.CancellationToken);
var scalar = builder.Variables.Single().Attr;
scalar.IsArray.ShouldBeFalse("null ArrayCount is scalar");
scalar.ArrayDim.ShouldBeNull();
}
/// <summary>Verifies a read of an isArray:true arrayLength:1 equipment tag returns a 1-element typed array.</summary>
[Fact]
public void DecodeArrayBlock_count_of_one_returns_single_element_array()
{
// A 1-element Int16 array: one big-endian word.
var block = BeWords(0x0064); // 100
var result = S7Driver.DecodeArrayBlock(ArrTag(S7DataType.Int16, 1), Addr(S7Size.Word), block);
var arr = result.ShouldBeOfType<short[]>();
arr.Length.ShouldBe(1);
arr[0].ShouldBe((short)100);
}
// ── Equipment-tag resolver threads arrayLength → ArrayCount ───────────────────────────