pymodbus：从 Modbus 设备发出读取字符串和多种类型的数据

Question

我正在尝试从Modbus TCP设备读取String(Usecase-1) & multiple type of data in one request(Usecase-2) 数据，但未能正确解码。

系统配置：

Python 3.6.5
Pymodbus：2.1.0
平台：Windows 10 64 位

Modbus TCP 服务器：

import logging

from pymodbus.constants import Endian

from pymodbus.datastore import ModbusSequentialDataBlock

from pymodbus.datastore import ModbusSlaveContext, ModbusServerContext

from pymodbus.device import ModbusDeviceIdentification

from pymodbus.payload import BinaryPayloadBuilder

from pymodbus.server.sync import StartTcpServer

class ModbusTCPServer(object):

    # initialize your data store:

    hrBuilder = BinaryPayloadBuilder(byteorder=Endian.Big, wordorder=Endian.Big)

    # Usecase-1

    hrBuilder.add_string("abcdefghij")

    #Uncomment below three lines for usecase-2

    # hrBuilder.add_32bit_float(20.5) 

    # hrBuilder.add_32bit_int(45) 

    # hrBuilder.add_bits([1, 0, 0, 0, 0, 0, 0, 0])

    hrBlock = ModbusSequentialDataBlock(0, hrBuilder.to_registers() * 100)

    store = ModbusSlaveContext(hr=hrBlock, ir=hrBlock, di=hrBlock, co=hrBlock)

    slaves = {

        1: store,

    }

    context = ModbusServerContext(slaves=slaves, single=False)

    # initialize the server information    

    identity = ModbusDeviceIdentification()

    modbusDeviceAddress = "127.0.0.1"

    modbusDevicePort = 501

    # run the TCP server

    # TCP:

    print("Modbus TCP Server started.")

    StartTcpServer(context, identity=identity, address=(modbusDeviceAddress, modbusDevicePort))

if __name__ == "__main__":

    print("Reading application configurations...")

    ModbusTCPServer();

Answer 1

使用zero_mode=True在ModbusSlaveContext。如果要将[0..n]客户端中的寄存器映射到[0..n]服务器中。默认情况下，pymodbus 服务器将寄存器读取地址映射[0..n]到[1..n]其内部存储中的寄存器。这是为了遵守 modbus 规范。引用 pymodbus 源代码。#The slave context can also be initialized in zero_mode which means that a# request to address(0-7) will map to the address (0-7). The default is# False which is based on section 4.4 of the specification, so address(0-7)# will map to (1-8)::因此，在您的情况下，您可以设置ModbusSequentialDataBlockto的起始地址1或ModbusSlaveContext使用zero_mode=True.    hrBlock = ModbusSequentialDataBlock(1, hrBuilder.to_registers() * 100)    # Or    store = ModbusSlaveContext(hr=hrBlock, ir=hrBlock, di=hrBlock, co=hrBlock, zero_mode=True)