Joseph Doherty
28 lines
1.1 KiB
C#
28 lines
1.1 KiB
C#
using Shouldly;
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using Xunit;
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namespace ZB.MOM.WW.OtOpcUa.Driver.Modbus.Tests;
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public sealed class ModbusCrcTests
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{
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// Known CRC-16/MODBUS vectors (init 0xFFFF, poly 0xA001). CRC returned as ushort;
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// on the wire it is appended low-byte-first.
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[Theory]
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// FC03 read HR: unit 1, addr 0, qty 1 -> CRC 0x0A84 (bytes 84 0A on the wire)
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[InlineData(new byte[] { 0x01, 0x03, 0x00, 0x00, 0x00, 0x01 }, (ushort)0x0A84)]
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// "123456789" canonical check value for CRC-16/MODBUS = 0x4B37
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[InlineData(new byte[] { 0x31,0x32,0x33,0x34,0x35,0x36,0x37,0x38,0x39 }, (ushort)0x4B37)]
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public void Compute_matches_known_vectors(byte[] frame, ushort expected)
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=> ModbusCrc.Compute(frame).ShouldBe(expected);
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[Fact]
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public void AppendLowByteFirst_writes_lo_then_hi()
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{
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var body = new byte[] { 0x01, 0x03, 0x00, 0x00, 0x00, 0x01 };
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var withCrc = ModbusCrc.Append(body);
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withCrc.Length.ShouldBe(body.Length + 2);
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withCrc[^2].ShouldBe((byte)0x84); // CRC low byte
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withCrc[^1].ShouldBe((byte)0x0A); // CRC high byte
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}
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}
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