TS_Modbus: Connect to devices by protocol modbus TCP/RTU

TSModbus allows you to communicate with slave devices by Modbus TCP, RTU and RTU via TCP protocols. Now TSModbus supports the mode of Master.

This module requires only one dependency. It is serial to work through a com port.

This module was written for the reason that I needed to know a little more about the request in my projects than the existing packages could provide. I hope that TS_Modbus will also be useful to someone.

How it works

Create connection class for your network and open connection For TCP:

conn = connections.TCPConnection({
    'ip': '10.100.3.231',
    'port': 502
})
conn.open_connection(timeout=10)

For COM:

conn = connections.COMConnection({
    'COM': 'COM1',
    'baudrate': 115200,
    'parity': serial.PARITY_NONE,
    'bytesizes': serial.EIGHTBITS,
    'stopbits': serial.STOPBITS_ONE
})
conn.open_connection(timeout=10)

Create class for modbus protocol. For Modbus TCP:

mb = modbusTCP_client.TSMbTCPClient()

For Modbus RTU:

mb = modbusRTU_client.TSMbRTUClient()

If you need Modbus RTU protocol via TCP connection you have to create TCP connection class and TSMbRTUClient for protocol. Use functions execute (for single request) and execute_ext (for several requests) to communicate with slave devices. How to use these functions, see the examples below or in the repository.

Examples 1: Send single request to the device

data = mb.execute(conn, function=const.READ_INPUT_REGISTERS, device_address=1, start_address=0, regs_quantity=10)

Response of this function is values list of readed registers. If it is write modbus function - result is empty set. You can give more information about request. There is ts_last_request param in mb class. You can do:

print(str(data) + ': ' + str(mb.ts_last_request['response_time']) + ' мс')
print(str(mb.ts_last_request) + ': ' + str(mb.ts_last_request['response_time']) + ' мс')

Result is:

(7480, 3, 3, 3, 0, 0, 0, 0, 0, 0): 39.68095779418945 мс
{'error': 0, 'function': 4, 'device_address': 1, 'start_address': 0, 'regs_quantity': 10, 'request': b'\x00\x01\x00\x00\x00\x06\x01\x04\x00\x00\x00\n', 'response': b'\x00\x01\x00\x00\x00\x17\x01\x04\x14\x1d8\x00\x03\x00\x03\x00\x03\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00\x00', 'response_time': 39.68095779418945, 'values': [], 'data': (7480, 3, 3, 3, 0, 0, 0, 0, 0, 0)}: 39.68095779418945 мс

Param ts_last_request has fields:

        self.ts_last_request = {
                            'error': 0,            # Modbus Error Code
                            'function': 0,         # Request function code
                            'device_address': 0,   # Device address
                            'start_address': 0,    # Start Address
                            'regs_quantity': 0,    # Quantity of registers
                            'request': b'',        # Submitted request in hexadecimal format
                            'response': b'',       # Response in hexadecimal format
                            'response_time': 0.0,  # Response time of request
                            'values': [],          # Values (for write modbus functions)
                            'data': []             # Data (for read modbus functions)
        }

Examples 2: Send single command to the device

data = mb.execute(conn, 
                function=const.WRITE_MULTIPLE_REGISTERS, 
                device_address=1, 
                start_address=500, 
                values=[1, 2, 3])

TS_Modbus will write as many values as are transferred in the value list

Examples 3: Send several requests to the device

You can send several comands by one function. This function is execute_ext:

result = mb.execute_ext(conn, [{'function': const.READ_INPUT_REGISTERS,
                                'device_address': 1,
                                'start_address': 12300,
                                'regs_quantity': 3},
                               {'function': const.WRITE_MULTIPLE_REGISTERS,
                                'device_address': 1,
                                'start_address': 12300,
                                'values': [1, 2, 3]},
                               {'function': const.READ_INPUT_REGISTERS,
                                'device_address': 1,
                                'start_address': 12300,
                                'regs_quantity': 3},
                               {'function': const.WRITE_MULTIPLE_REGISTERS,
                                'device_address': 1,
                                'start_address': 12300,
                                'values': [0, 0, 0]}
                               ])

The result of this function is an array of arrays with a list of values for each request. Params of all requests saved in ts_requests_ext field.

print(result)
print(mb.ts_requests_ext)

[(0, 0, 0), [], (1, 2, 3), []]
[{'error': 0, 'function': 16, 'device_address': 1, 'start_address': 12300, 'regs_quantity': 3, 'request': b'\x00\x07\x00\x00\x00\r\x01\x100\x0c\x00\x03\x06\x00\x00\x00\x00\x00\x00', 'response': b'\x00\x07\x00\x00\x00\x06\x01\x100\x0c\x00\x03', 'response_time': 31.81004524230957, 'values': [0, 0, 0], 'data': []}, {'error': 0, 'function': 16, 'device_address': 1, 'start_address': 12300, 'regs_quantity': 3, 'request': b'\x00\x07\x00\x00\x00\r\x01\x100\x0c\x00\x03\x06\x00\x00\x00\x00\x00\x00', 'response': b'\x00\x07\x00\x00\x00\x06\x01\x100\x0c\x00\x03', 'response_time': 31.81004524230957, 'values': [0, 0, 0], 'data': []}, {'error': 0, 'function': 16, 'device_address': 1, 'start_address': 12300, 'regs_quantity': 3, 'request': b'\x00\x07\x00\x00\x00\r\x01\x100\x0c\x00\x03\x06\x00\x00\x00\x00\x00\x00', 'response': b'\x00\x07\x00\x00\x00\x06\x01\x100\x0c\x00\x03', 'response_time': 31.81004524230957, 'values': [0, 0, 0], 'data': []}, {'error': 0, 'function': 16, 'device_address': 1, 'start_address': 12300, 'regs_quantity': 3, 'request': b'\x00\x07\x00\x00\x00\r\x01\x100\x0c\x00\x03\x06\x00\x00\x00\x00\x00\x00', 'response': b'\x00\x07\x00\x00\x00\x06\x01\x100\x0c\x00\x03', 'response_time': 31.81004524230957, 'values': [0, 0, 0], 'data': []}]