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Pymodbus Synchronous Client Examples
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--------------------------------------------------------------------------
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The following is an example of how to use the synchronous modbus client
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implementation from pymodbus.
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It should be noted that the client can also be used with
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the guard construct that is available in python 2.5 and up::
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with ModbusClient('127.0.0.1') as client:
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result = client.read_coils(1,10)
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#---------------------------------------------------------------------------#
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# import the various server implementations
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#---------------------------------------------------------------------------#
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from pymodbus.client.sync import ModbusTcpClient as ModbusClient
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#from pymodbus.client.sync import ModbusUdpClient as ModbusClient
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#from pymodbus.client.sync import ModbusSerialClient as ModbusClient
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#---------------------------------------------------------------------------#
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# configure the client logging
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#---------------------------------------------------------------------------#
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log = logging.getLogger()
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log.setLevel(logging.DEBUG)
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#---------------------------------------------------------------------------#
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# choose the client you want
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#---------------------------------------------------------------------------#
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# make sure to start an implementation to hit against. For this
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# you can use an existing device, the reference implementation in the tools
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# directory, or start a pymodbus server.
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#---------------------------------------------------------------------------#
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client = ModbusClient('127.0.0.1')
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#---------------------------------------------------------------------------#
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#---------------------------------------------------------------------------#
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# simply call the methods that you would like to use. An example session
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# is displayed below along with some assert checks. Note that some modbus
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# implementations differentiate holding/input discrete/coils and as such
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# you will not be able to write to these, therefore the starting values
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# are not known to these tests. Furthermore, some use the same memory
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# blocks for the two sets, so a change to one is a change to the other.
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# Keep both of these cases in mind when testing as the following will
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# _only_ pass with the supplied async modbus server (script supplied).
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#---------------------------------------------------------------------------#
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rq = client.write_coil(1, True)
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rr = client.read_coils(1,1)
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assert(rq.function_code < 0x80) # test that we are not an error
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assert(rr.bits[0] == True) # test the expected value
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rq = client.write_coils(1, [True]*8)
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rr = client.read_coils(1,8)
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assert(rq.function_code < 0x80) # test that we are not an error
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assert(rr.bits == [True]*8) # test the expected value
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rq = client.write_coils(1, [False]*8)
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rr = client.read_discrete_inputs(1,8)
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assert(rq.function_code < 0x80) # test that we are not an error
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assert(rr.bits == [True]*8) # test the expected value
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rq = client.write_register(1, 10)
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rr = client.read_holding_registers(1,1)
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assert(rq.function_code < 0x80) # test that we are not an error
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assert(rr.registers[0] == 10) # test the expected value
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rq = client.write_registers(1, [10]*8)
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rr = client.read_input_registers(1,8)
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assert(rq.function_code < 0x80) # test that we are not an error
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assert(rr.registers == [17]*8) # test the expected value
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'write_registers': [20]*8,
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rq = client.readwrite_registers(**arguments)
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rr = client.read_input_registers(1,8)
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assert(rq.function_code < 0x80) # test that we are not an error
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assert(rq.registers == [20]*8) # test the expected value
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assert(rr.registers == [17]*8) # test the expected value
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#---------------------------------------------------------------------------#
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#---------------------------------------------------------------------------#
added
removed
examples/common/synchronous-client.py
