与 Elfin EW11 RS485 wifi 转换器通信答案

【问题标题】：Communicate with Elfin EW11 RS485 wifi converter与 Elfin EW11 RS485 wifi 转换器通信
【发布时间】：2021-12-30 10:33:58
【问题描述】：

我正在尝试与具有 RS485 modbus 接口的电表 (Orno WE-517) 通信。此串行接口连接到 Elfin EW11 modbus 到 Wifi 转换器。

使用 pymodbus，我可以连接到适配器，但我无法从仪表中读取任何内容。这是我的代码：

from pymodbus.client.sync import ModbusTcpClient

from pprint import pprint

import logging
FORMAT = ('%(asctime)-15s %(threadName)-15s '
          '%(levelname)-8s %(module)-15s:%(lineno)-8s %(message)s')
logging.basicConfig(format=FORMAT)
log = logging.getLogger()

log.setLevel(logging.DEBUG)

client = ModbusTcpClient('192.168.0.18', 502)
if not client.connect():
    print('Error connecting')
    exit()

print('holding register')
result = client.read_holding_registers(28,1)
response = client.execute(result)
pprint(vars(response))

client.close()

这是脚本的输出：

python3 modBus.py

2021-12-30 10:46:44,112 MainThread      DEBUG    sync           :216      Connection to Modbus server established. Socket ('192.168.0.10', 47763)
holding register
2021-12-30 10:46:44,113 MainThread      DEBUG    transaction    :140      Current transaction state - IDLE
2021-12-30 10:46:44,114 MainThread      DEBUG    transaction    :145      Running transaction 1
2021-12-30 10:46:44,114 MainThread      DEBUG    transaction    :273      SEND: 0x0 0x1 0x0 0x0 0x0 0x6 0x0 0x3 0x0 0x1c 0x0 0x1
2021-12-30 10:46:44,115 MainThread      DEBUG    sync           :76       New Transaction state 'SENDING'
2021-12-30 10:46:44,115 MainThread      DEBUG    transaction    :287      Changing transaction state from 'SENDING' to 'WAITING FOR REPLY'
2021-12-30 10:46:44,216 MainThread      DEBUG    transaction    :375      Changing transaction state from 'WAITING FOR REPLY' to 'PROCESSING REPLY'
2021-12-30 10:46:44,217 MainThread      DEBUG    transaction    :297      RECV: 0x0 0x1 0x0 0x0 0x0 0x5 0x1 0x3 0x2 0x3e 0xf0
2021-12-30 10:46:44,218 MainThread      DEBUG    socket_framer  :147      Processing: 0x0 0x1 0x0 0x0 0x0 0x5 0x1 0x3 0x2 0x3e 0xf0
2021-12-30 10:46:44,218 MainThread      DEBUG    factory        :266      Factory Response[ReadHoldingRegistersResponse: 3]
2021-12-30 10:46:44,219 MainThread      DEBUG    transaction    :454      Adding transaction 1
2021-12-30 10:46:44,220 MainThread      DEBUG    transaction    :465      Getting transaction 1
2021-12-30 10:46:44,220 MainThread      DEBUG    transaction    :224      Changing transaction state from 'PROCESSING REPLY' to 'TRANSACTION_COMPLETE'
2021-12-30 10:46:44,221 MainThread      DEBUG    transaction    :140      Current transaction state - TRANSACTION_COMPLETE
2021-12-30 10:46:44,221 MainThread      DEBUG    transaction    :145      Running transaction 2
2021-12-30 10:46:44,222 MainThread      DEBUG    transaction    :273      SEND: 0x0 0x2 0x0 0x0 0x0 0x5 0x1 0x3 0x2 0x3e 0xf0
2021-12-30 10:46:44,222 MainThread      DEBUG    sync           :76       New Transaction state 'SENDING'
2021-12-30 10:46:44,223 MainThread      DEBUG    transaction    :287      Changing transaction state from 'SENDING' to 'WAITING FOR REPLY'
2021-12-30 10:46:47,227 MainThread      DEBUG    transaction    :303      Transaction failed. (Modbus Error: [Invalid Message] No response received, expected at least 8 bytes (0 received))
2021-12-30 10:46:47,228 MainThread      DEBUG    socket_framer  :147      Processing:
2021-12-30 10:46:47,228 MainThread      DEBUG    transaction    :465      Getting transaction 2
2021-12-30 10:46:47,229 MainThread      DEBUG    transaction    :224      Changing transaction state from 'PROCESSING REPLY' to 'TRANSACTION_COMPLETE'
{'fcode': 3,
 'message': '[Input/Output] Modbus Error: [Invalid Message] No response '
            'received, expected at least 8 bytes (0 received)',
 'string': '[Input/Output] Modbus Error: [Invalid Message] No response '
           'received, expected at least 8 bytes (0 received)'}

如您所见，pymodbus 管理连接、发送请求和接收响应。但我无法从该响应中找到做某事的方法。

有人有什么想法可以帮助我吗？

提前，非常感谢您的帮助:)

【问题讨论】：

标签： pymodbus

【解决方案1】：

您要读取哪个仪表？

尝试添加

从 pymodbus.constants 导入 Endian
从 pymodbus.payload 导入 BinaryPayloadDecoder

改变

result = client.read_holding_registers(address=28, count=2, unit=1)

添加

if not result.isError():
    print(BinaryPayloadDecoder.fromRegisters(result.registers,
    byteorder=Endian.Big,
    wordorder=Endian.Big).decode_32bit_float())

如果未解决后仪表模型以获得准确答案

【讨论】：

非常感谢您的回复和帮助。我编辑了最初的问题以添加对仪表的引用（Orno WE-517）。同时，我设法找到了解决方案。我将在另一个回复中发布我最终得到的代码。谢谢

【解决方案2】：

坚持寻找解决方案，我发现这些值实际上是浮动的。这导致我找到以下解决方案：

from pymodbus.client.sync import ModbusTcpClient
from pymodbus.payload import BinaryPayloadDecoder

client = ModbusTcpClient('192.168.0.18', 502)
if not client.connect():
    print('Error connecting')
    exit()

result = client.read_holding_registers(0x1C, 2)
decoder = BinaryPayloadDecoder.fromRegisters(result.registers, '>', '>')
print(decoder.decode_32bit_float())

client.close()

解决办法真的是找到BinaryPayloadDecoder的各种方法。

【讨论】：