使用Pymodbus将RS232 Ascii转换为Modbus TCP

Question

我正在尝试使用pymodbus Callback Sever将RS252 Ascii字符串数据从传感器转换为Modbus TCP输入/保持寄存器，服务器是请求客户端记录器时的主报告数据，我不知道我需要做什么才能得到这个上班。我目前能够读取数据并使用它将其记录到csv文件中

#!/usr/bin/env python
# Log data from serial port


import argparse
import serial
import datetime
import time
import os


parser = argparse.ArgumentParser(formatter_class=argparse.ArgumentDefaultsHelpFormatter)
parser.add_argument("-d", "--device", help="device to read from", default="/dev/ttyUSB0")
parser.add_argument("-s", "--speed", help="speed in bps", default=9600, type=int)
args = parser.parse_args()

outputFilePath = os.path.join(os.path.dirname(__file__),
                 datetime.datetime.now().strftime("%Y-%m-%d") + ".csv")

with serial.Serial(args.device, args.speed) as ser, open(outputFilePath,'w') as outputFile:
    print("Logging started. Ctrl-C to stop.") 
    try:
        while True:
            time.sleep(0.2) 
            x = (ser.read(ser.inWaiting())) 
            data = x.decode('UTF-8')
            if data !="":
                outputFile.write(time.strftime("%Y/%m/%d %H:%M ") + " " + data  )
                outputFile.flush()

    except KeyboardInterrupt:
        print("Logging stopped")

来自传感器的字符串来自设备：

 0.00 0.0 0.0 346.70 25.14

我需要将每个部分作为自己的Modbus寄存器，我正在尝试在Raspberry Pi Zero上使用pymodbus。传感器每秒更新4次，我能够将数据分成几部分，我只是避开了;因为我不确定在Callback脚本中我需要做什么，所以我还不熟悉Python我还在学习。我对Modbus TCP有所了解，并且之前在Arduino系统上使用过它。任何帮助，将不胜感激。

Answer 1

你需要的是updating server，你可以用来填充寄存器。您将不得不专注于函数def updating_writer并进行串行读取，处理它们并写入您选择的寄存器。这个例子很难在第一时间阅读和理解。我修改了example以满足您的需求。但是这里有一些关键概念可以方便地理解代码。

ModbusSlaveContext

BinaryPayloadBuilder

另请注意，该示例使用基于twisted的异步服务器，如果您是新手，或者有一些限制，不允许您在目标上使用扭曲，您也可以通过简单的线程实现相同。设计大致是这样的。

1. 在单独的线程中启动更新功能
2. 最后启动TCP服务器（阻止）

# Complete gist here --> https://gist.github.com/dhoomakethu/540b15781c62de6d1f7c318c3fc8ae22
def updating_writer(context, device, baudrate):
    """ A worker process that runs every so often and
    updates live values of the context. It should be noted
    that there is a race condition for the update.
    :param arguments: The input arguments to the call
    """
    log.debug("updating the context")
    log.debug("device - {}, baudrate-{}".format(device, baudrate))
    data = serial_reader(device, baudrate)  # Implement your serial reads, return list of floats.
    if data:
        # We can not directly write float values to registers, Use BinaryPayloadBuilder to convert float to IEEE-754 hex integer
        for d in data:
            builder.add_32bit_float(d)
        registers = builder.to_registers()
        context = context
        register = 3  # Modbus function code (3) read holding registers. Just to uniquely identify what we are reading from /writing in to.
        slave_id = 0x01 # Device Unit address , refer ModbusSlaveContext below
        address = 0x00 # starting offset of register to write (0 --> 40001)
        log.debug("new values: " + str(registers))
        context[slave_id].setValues(register, address, registers)

一旦服务器运行并且值正在更新，您可以使用客户端读取值并将其解析回浮动。

from pymodbus.client.sync import ModbusTcpClient as Client
from pymodbus.payload import BinaryPayloadDecoder, Endian
client = Client(<IP-ADDRESS>, port=5020)

# Each 32 bit float is stored in 2 words, so we will read 10 registers 
raw_values = client.read_holding_registers(0, 10, unit=1)
if not registers.isError():
    registers = raw_values.registers
    decoder = BinaryPayloadDecoder.fromRegisters(registers, 
    wordorder=Endian.Big, byteorder=Endian.Big)

    for _ in range(5):
        print(decoder.decode_32bit_float())