基于TCP的Python Modbus RTU

Question

我试图用python在Modbus TCP上读写数据。当我在下面的设置中使用ModbusPoll时，一切都可以工作。

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我现在尝试用python读取数据，并为此使用了[医]绿脓杆菌库。我的代码如下所示：

from pymodbus.client.sync import ModbusTcpClient
from pymodbus.transaction import ModbusRtuFramer as ModbusFramer

client = ModbusTcpClient("192.168.0.7", port=502, framer=ModbusFramer)
success = client.connect()

read = client.read_holding_registers(address=4000)
read.registers

但我总是会犯以下错误：

接收到ModbusIOException(InvalidMessageReceivedException('No响应，预期至少有2个字节(0接收到)，1)

Answer 1

读取保存寄存器需要一个单元来正确地读取消息。

read = client.read_holding_registers(address=4000, unit=1)

Answer 2

这就是帮我的忙。

检查设备的slave_ID (unit=slave_ID)。它不是议会1或0。例如，在我的例子中- 240。

result = client.read_holding_registers(address=0x0010, count = 2, **unit=240**)

文件上说：

    def write_register(self, address, value, **kwargs):
    '''

    :param address: The starting address to write to
    :param value: The value to write to the specified address
    **:param unit: The slave unit this request is targeting**
    :returns: A deferred response handle
    '''

和：

    def read_holding_registers(self, address, count=1, **kwargs):
    '''

    :param address: The starting address to read from
    :param count: The number of registers to read
    **:param unit: The slave unit this request is targeting**
    :returns: A deferred response handle
    '''

查看文件"common.py“或在光标处于函数状态时按Ctrl+B。