61 lines
2.3 KiB
C#
61 lines
2.3 KiB
C#
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namespace Modbus
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{
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/// <summary>
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/// Defines constants related to the Modbus protocol.
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/// </summary>
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internal static class Modbus
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{
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// supported function codes
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public const byte ReadCoils = 1;
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public const byte ReadInputs = 2;
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public const byte ReadHoldingRegisters = 3;
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public const byte ReadInputRegisters = 4;
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public const byte WriteSingleCoil = 5;
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public const byte WriteSingleRegister = 6;
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public const byte Diagnostics = 8;
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public const ushort DiagnosticsReturnQueryData = 0;
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public const byte WriteMultipleCoils = 15;
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public const byte WriteMultipleRegisters = 16;
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public const byte ReadWriteMultipleRegisters = 23;
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public const int MaximumDiscreteRequestResponseSize = 2040;
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public const int MaximumRegisterRequestResponseSize = 127;
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// modbus slave exception offset that is added to the function code, to flag an exception
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public const byte ExceptionOffset = 128;
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// modbus slave exception codes
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public const byte IllegalFunction = 1;
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public const byte IllegalDataAddress = 2;
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public const byte Acknowledge = 5;
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public const byte SlaveDeviceBusy = 6;
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// default setting for number of retries for IO operations
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public const int DefaultRetries = 3;
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// default number of milliseconds to wait after encountering an ACKNOWLEGE or SLAVE DEVIC BUSY slave exception response.
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public const int DefaultWaitToRetryMilliseconds = 250;
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// default setting for IO timeouts in milliseconds
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public const int DefaultTimeout = 1000;
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// smallest supported message frame size (sans checksum)
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public const int MinimumFrameSize = 2;
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public const ushort CoilOn = 0xFF00;
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public const ushort CoilOff = 0x0000;
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// IP slaves should be addressed by IP
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public const byte DefaultIpSlaveUnitId = 0;
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// An existing connection was forcibly closed by the remote host
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public const int ConnectionResetByPeer = 10054;
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// Existing socket connection is being closed
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public const int WSACancelBlockingCall = 10004;
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// used by the ASCII tranport to indicate end of message
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public const string NewLine = "\r\n";
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}
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}
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