Source code for pymodbus.constants
'''
Constants For Modbus Server/Client
----------------------------------
This is the single location for storing default
values for the servers and clients.
'''
from pymodbus.interfaces import Singleton
[docs]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
[docs]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
[docs]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 = '<'
[docs]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
[docs]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",
]