text: '''
  Constants For Modbus Server/Client
  ----------------------------------
  
  This is the single location for storing default
  values for the servers and clients.
  '''
  from pymodbus.interfaces import Singleton
  
  
  class Defaults(Singleton):
      ''' A collection of modbus default values
  
      .. attribute:: Port
  
         The default modbus tcp server port (502)
  
      .. attribute:: Retries
  
         The default number of times a client should retry the given
         request before failing (3)
  
      .. attribute:: RetryOnEmpty
  
         A flag indicating if a transaction should be retried in the
         case that an empty response is received. This is useful for
         slow clients that may need more time to process a requst.
  
      .. attribute:: Timeout
  
         The default amount of time a client should wait for a request
         to be processed (3 seconds)
  
      .. attribute:: Reconnects
  
         The default number of times a client should attempt to reconnect
         before deciding the server is down (0)
  
      .. attribute:: TransactionId
  
         The starting transaction identifier number (0)
  
      .. attribute:: ProtocolId
  
         The modbus protocol id.  Currently this is set to 0 in all
         but proprietary implementations.
  
      .. attribute:: UnitId
  
         The modbus slave addrss.  Currently this is set to 0x00 which
         means this request should be broadcast to all the slave devices
         (really means that all the devices should respons).
  
      .. attribute:: Baudrate
  
         The speed at which the data is transmitted over the serial line.
         This defaults to 19200.
  
      .. attribute:: Parity
  
         The type of checksum to use to verify data integrity. This can be
         on of the following::
  
           - (E)ven - 1 0 1 0 | P(0)
           - (O)dd  - 1 0 1 0 | P(1)
           - (N)one - 1 0 1 0 | no parity
  
         This defaults to (N)one.
  
      .. attribute:: Bytesize
  
         The number of bits in a byte of serial data.  This can be one of
         5, 6, 7, or 8. This defaults to 8.
  
      .. attribute:: Stopbits
  
         The number of bits sent after each character in a message to
         indicate the end of the byte.  This defaults to 1.
  
      .. attribute:: ZeroMode
  
         Indicates if the slave datastore should use indexing at 0 or 1.
         More about this can be read in section 4.4 of the modbus specification.
  
      .. attribute:: IgnoreMissingSlaves
  
         In case a request is made to a missing slave, this defines if an error
         should be returned or simply ignored. This is useful for the case of a
         serial server emulater where a request to a non-existant slave on a bus
         will never respond. The client in this case will simply timeout.
      '''
      Port                = 502
      Retries             = 3
      RetryOnEmpty        = False
      Timeout             = 3
      Reconnects          = 0
      TransactionId       = 0
      ProtocolId          = 0
      UnitId              = 0x00
      Baudrate            = 19200
      Parity              = 'N'
      Bytesize            = 8
      Stopbits            = 1
      ZeroMode            = False
      IgnoreMissingSlaves = False
      ReadSize            = 1024
  
  class ModbusStatus(Singleton):
      '''
      These represent various status codes in the modbus
      protocol.
  
      .. attribute:: Waiting
  
         This indicates that a modbus device is currently
         waiting for a given request to finish some running task.
  
      .. attribute:: Ready
  
         This indicates that a modbus device is currently
         free to perform the next request task.
  
      .. attribute:: On
  
         This indicates that the given modbus entity is on
  
      .. attribute:: Off
  
         This indicates that the given modbus entity is off
  
      .. attribute:: SlaveOn
  
         This indicates that the given modbus slave is running
  
      .. attribute:: SlaveOff
  
         This indicates that the given modbus slave is not running
      '''
      Waiting  = 0xffff
      Ready    = 0x0000
      On       = 0xff00
      Off      = 0x0000
      SlaveOn  = 0xff
      SlaveOff = 0x00
  
  
  class Endian(Singleton):
      ''' An enumeration representing the various byte endianess.
  
      .. attribute:: Auto
  
         This indicates that the byte order is chosen by the
         current native environment.
  
      .. attribute:: Big
  
         This indicates that the bytes are in little endian format
  
      .. attribute:: Little
  
         This indicates that the bytes are in big endian format
  
      .. note:: I am simply borrowing the format strings from the
         python struct module for my convenience.
      '''
      Auto   = '@'
      Big    = '>'
      Little = '<'
  
  
  class ModbusPlusOperation(Singleton):
      ''' Represents the type of modbus plus request
  
      .. attribute:: GetStatistics
  
         Operation requesting that the current modbus plus statistics
         be returned in the response.
  
      .. attribute:: ClearStatistics
  
         Operation requesting that the current modbus plus statistics
         be cleared and not returned in the response.
      '''
      GetStatistics   = 0x0003
      ClearStatistics = 0x0004
  
  
  class DeviceInformation(Singleton):
      ''' Represents what type of device information to read
  
      .. attribute:: Basic
  
         This is the basic (required) device information to be returned.
         This includes VendorName, ProductCode, and MajorMinorRevision
         code.
  
      .. attribute:: Regular
  
         In addition to basic data objects, the device provides additional
         and optinoal identification and description data objects. All of
         the objects of this category are defined in the standard but their
         implementation is optional.
  
      .. attribute:: Extended
  
         In addition to regular data objects, the device provides additional
         and optional identification and description private data about the
         physical device itself. All of these data are device dependent.
  
      .. attribute:: Specific
  
         Request to return a single data object.
      '''
      Basic    = 0x01
      Regular  = 0x02
      Extended = 0x03
      Specific = 0x04
  
  
  class MoreData(Singleton):
      ''' Represents the more follows condition
  
      .. attribute:: Nothing
  
         This indiates that no more objects are going to be returned.
  
      .. attribute:: KeepReading
  
         This indicates that there are more objects to be returned.
      '''
      Nothing     = 0x00
      KeepReading = 0xFF
  
  #---------------------------------------------------------------------------#
  # Exported Identifiers
  #---------------------------------------------------------------------------#
  __all__ = [
      "Defaults", "ModbusStatus", "Endian",
      "ModbusPlusOperation",
      "DeviceInformation", "MoreData",
  ]
  