namespace NModbus.Interfaces

{

public enum ModbusExceptionCode : byte

{

/// <summary>

/// The function code received in the query is not an

/// allowable action for the server. This may be

/// because the function code is only applicable to

/// newer devices, and was not implemented in the

/// unit selected. It could also indicate that the server

/// is in the wrong state to process a request of this

/// type, for example because it is unconfigured and

/// is being asked to return register values.

/// </summary>

IllegalFunction = 0x01,

/// <summary>

/// The data address received in the query is not an

/// allowable address for the server. More

/// specifically, the combination of reference number

/// and transfer length is invalid. For a controller with

/// 100 registers, the PDU addresses the first register

/// as 0, and the last one as 99. If a request is

/// submitted with a starting register address of 96

/// and a quantity of registers of 4, then this request

/// will successfully operate (address-wise at least)

/// on registers 96, 97, 98, 99. If a request is

/// submitted with a starting register address of 96

/// and a quantity of registers of 5, then this request

/// will fail with Exception Code 0x02 “Illegal Data

/// Address” since it attempts to operate on registers

/// 96, 97, 98, 99 and 100, and there is no register

/// with address 100.

/// </summary>

IllegalDataAddress = 0x02,

/// <summary>

/// A value contained in the query data field is not an

/// allowable value for server. This indicates a fault in

/// the structure of the remainder of a complex

/// request, such as that the implied length is

/// incorrect. It specifically does NOT mean that a

/// data item submitted for storage in a register has a

/// value outside the expectation of the application

/// program, since the MODBUS protocol is unaware

/// of the significance of any particular value of any

/// particular register.

/// </summary>

IllegalDataValue = 0x03,

/// <summary>

/// An unrecoverable error occurred while the server

/// was attempting to perform the requested action.

/// </summary>

ServerDeviceFailure = 0x04,

/// <summary>

/// Specialized use in conjunction with programming

/// commands.

/// The server has accepted the request and is

/// processing it, but a long duration of time will be

/// required to do so. This response is returned to

/// prevent a timeout error from occurring in the

/// client. The client can next issue a Poll Program

/// Complete message to determine if processing is

/// completed.

/// </summary>

Acknowledge = 0x05,

/// <summary>

/// Specialized use in conjunction with programming

/// commands.

/// The server is engaged in processing a long–

/// duration program command. The client should

/// retransmit the message later when the server is

/// free.

/// </summary>

ServerDeviceBusy = 0x06,

/// <summary>

/// Specialized use in conjunction with function codes

/// 20 and 21 and reference type 6, to indicate that

/// the extended file area failed to pass a consistency

/// check.

/// The server attempted to read record file, but

/// detected a parity error in the memory. The client

/// can retry the request, but service may be required.

/// </summary>

MemoryParityError = 0x08,

/// <summary>

/// Specialized use in conjunction with gateways,

/// indicates that the gateway was unable to allocate

/// an internal communication path from the input port

/// to the output port for processing the request.

/// Usually means that the gateway is misconfigured

/// or overloaded

/// </summary>

GatewayPathUnavailable = 0x0a,

/// <summary>

/// Specialized use in conjunction with gateways,

/// indicates that no response was obtained from the

/// target device. Usually means that the device is not

/// present on the network.

/// </summary>

GatewayTargetDeviceFailedToRespond = 0x0b

}

}