Using Pymodbus TCP Client implementaion

I'm using the following code to try and send data as a ModbusTCP slave:

import socket
import logging
from pymodbus.constants import Defaults
from pymodbus.factory import ClientDecoder
from pymodbus.exceptions import NotImplementedException, ParameterException
from pymodbus.exceptions import ConnectionException
from pymodbus.transaction import ModbusSocketFramer, ModbusBinaryFramer
from pymodbus.client.common import ModbusClientMixin
#------------------------------------------------------------------#
#Logging
#------------------------------------------------------------------#
_logger = logging.getLogger(__name__)
##------------------------------------------------------------------##
##The Synchronous Clients
##------------------------------------------------------------------##
class BaseModbusClient(ModbusClientMixin): def __init__(self, framer, **kwargs): self.framer = framer if isinstance(self.framer, ModbusSocketFramer): self.transaction = DictTrasactionManager(self, **kwargs) else: self.transcation = FitoTransactionManager(self, **kwargs) def connect(self): raise NotImplementedException("Method not implemented by derived class") def close(self): pass def _send(self, request): raise NotImplementedException("Method not implemented by derived class") def _recv(self, size): raise NotImplementedException("Method not implemented by derived class") def excecute(self, request=None): if not self.connect(): raise ConnectionException("Failed to connect[%s]" % (self.__str__())) return self.transaction.execute(request) def __enter__(self): if not self.connect(): raise ConnectionException("Failed to connect [%s]" % (self.__str__())) raise self def __exit__(self, klass, value, traceback): self.close() def __str__(self): return "Null Transport"
class ModbusTcpClient(BaseModbusClient): def __init__(self, host='192.168.3.2', port=Defaults.Port, framer=ModbusSocketFramer, **kwargs): self.host = host self.port = port self.source_address = kwargs.get('source_address', ('', 0)) BaseModbusClient.__init__(self,framer(ClientDecoder()), **kwargs) def connect(self): if self.socket: return True try: address = (self.host, self.port) self.socket = socket.create_connection((self.host, self.port), timeout=Defaults.Timeout, source_address=self.source_address) except socket.error, msg: _logger.error('Connection to (%s, %s) failed: %s' % (self.host, self.port, msg)) self.close() def close(self): if self.socket: self.socket.close() self.socket = None def _send(self, request): if not self.socket: raise ConnectionException(self.__str__()) if request: return self.socket.send(request) return 0 def _recv(self, size): if not self.socket: raise ConnectionException(self.__str__()) return self.socket.recv(size) def __str__(self): return "%s:%s" % (self.host, self.port)

Now im willing to start and use all these functions. How do I start? should I just call the functions I need? My will is to connect to the master as a slave and change register values.

Thanks for the answers.

1 Answer

This should get you started.

from pymodbus.client.sync import ModbusTcpClient
#modbus connection
client = ModbusTcpClient('192.168.1.100')
connection = client.connect()
#read register
request = client.read_holding_registers(xxxx,3) #covert to float
result = request.registers
#write to register
client.write_registers(xxxx, [xxxx,xxxx,xxxx])