Files
lmxopcua/tests/ZB.MOM.WW.OtOpcUa.Driver.Modbus.IntegrationTests/DL205/DL205StringQuirkTests.cs
Joseph Doherty cd19022d19 Phase 3 PR 45 -- DL205 string byte-order quirk (low-byte-first ASCII packing). Adds ModbusStringByteOrder enum {HighByteFirst, LowByteFirst} + StringByteOrder field on ModbusTagDefinition (default HighByteFirst, the standard Modbus convention). DecodeRegister + EncodeRegister String branches now respect per-tag byte order. Under LowByteFirst each register packs the first char in the low byte instead of the high byte -- the AutomationDirect DirectLOGIC DL205/DL260/DL350 family's headline string quirk. Without the flag the driver decodes 'eHllo' garbage from HR[1040..1042] even though wire bytes are identical. Unit tests: String_LowByteFirst_decodes_DL205_packed_Hello (5 chars across 3 regs with nul pad), String_LowByteFirst_decode_truncates_at_first_nul, String_LowByteFirst_encode_round_trips_with_decode (asserts exact DL205-documented byte sequence {0x65,0x48,0x6C,0x6C,0x00,0x6F} + symmetric encode->decode), String_HighByteFirst_and_LowByteFirst_differ_on_same_wire (control: same wire, different flag => different decode). 56/56 Modbus.Tests pass. Integration test: DL205StringQuirkTests.DL205_string_low_byte_first_decodes_Hello_from_HR1040 against the dl205.json pymodbus profile; reads HR[1040..1042] with both flags on the same tag map and asserts LowByteFirst='Hello' + HighByteFirst!='Hello'. Gated on MODBUS_SIM_PROFILE=dl205 since the standard profile doesn't seed HR[1040..1042]. Verified 2/2 integration tests pass against running pymodbus dl205 simulator. Baseline for PR 46 (BCD decoder), PR 47 (V-memory octal helper), PR 48 (CDAB float order), PR 49 (FC03/FC16 per-device caps) -- each lands its own DL205_<behavior> test class in tests/.../DL205/.
2026-04-18 21:43:32 -04:00

82 lines
3.6 KiB
C#

using Shouldly;
using Xunit;
namespace ZB.MOM.WW.OtOpcUa.Driver.Modbus.IntegrationTests.DL205;
/// <summary>
/// Verifies the DL205/DL260 low-byte-first ASCII string packing quirk against the
/// <c>dl205.json</c> pymodbus profile. Standard Modbus packs the first char of each pair
/// in the high byte of the register; DirectLOGIC packs it in the low byte instead. Without
/// <see cref="ModbusStringByteOrder.LowByteFirst"/> the driver decodes "eHllo" garbage
/// even though the bytes on the wire are identical.
/// </summary>
/// <remarks>
/// <para>
/// Requires the dl205 profile (<c>Pymodbus\serve.ps1 -Profile dl205</c>). The standard
/// profile does not seed HR[1040..1042] with string bytes, so running this against the
/// standard profile returns <c>"\0\0\0\0\0"</c> and the test fails. Skip when the env
/// var <c>MODBUS_SIM_PROFILE</c> is not set to <c>dl205</c>.
/// </para>
/// </remarks>
[Collection(ModbusSimulatorCollection.Name)]
[Trait("Category", "Integration")]
[Trait("Device", "DL205")]
public sealed class DL205StringQuirkTests(ModbusSimulatorFixture sim)
{
[Fact]
public async Task DL205_string_low_byte_first_decodes_Hello_from_HR1040()
{
if (sim.SkipReason is not null) Assert.Skip(sim.SkipReason);
if (!string.Equals(Environment.GetEnvironmentVariable("MODBUS_SIM_PROFILE"), "dl205",
StringComparison.OrdinalIgnoreCase))
{
Assert.Skip("MODBUS_SIM_PROFILE != dl205 — skipping (standard profile does not seed HR[1040..1042]).");
}
var options = new ModbusDriverOptions
{
Host = sim.Host,
Port = sim.Port,
UnitId = 1,
Timeout = TimeSpan.FromSeconds(2),
Tags =
[
new ModbusTagDefinition(
Name: "DL205_Hello_Low",
Region: ModbusRegion.HoldingRegisters,
Address: 1040,
DataType: ModbusDataType.String,
Writable: false,
StringLength: 5,
StringByteOrder: ModbusStringByteOrder.LowByteFirst),
// Control: same address, HighByteFirst, to prove the driver would have decoded
// garbage without the quirk flag.
new ModbusTagDefinition(
Name: "DL205_Hello_High",
Region: ModbusRegion.HoldingRegisters,
Address: 1040,
DataType: ModbusDataType.String,
Writable: false,
StringLength: 5,
StringByteOrder: ModbusStringByteOrder.HighByteFirst),
],
Probe = new ModbusProbeOptions { Enabled = false },
};
await using var driver = new ModbusDriver(options, driverInstanceId: "dl205-string");
await driver.InitializeAsync(driverConfigJson: "{}", TestContext.Current.CancellationToken);
var results = await driver.ReadAsync(["DL205_Hello_Low", "DL205_Hello_High"],
TestContext.Current.CancellationToken);
results.Count.ShouldBe(2);
results[0].StatusCode.ShouldBe(0u);
results[0].Value.ShouldBe("Hello", "DL205 low-byte-first ordering must produce 'Hello' from HR[1040..1042]");
// The high-byte-first read of the same wire bytes should differ — not asserting the
// exact garbage string (that would couple the test to the ASCII byte math) but the two
// decodes MUST disagree, otherwise the quirk flag is a no-op.
results[1].StatusCode.ShouldBe(0u);
results[1].Value.ShouldNotBe("Hello");
}
}