如何停止pymodbus异步Modbus服务器？

Question

我想停止一个pymodbus异步ModbusTcpServer，然后启动一个新的服务器，因此我尝试使用以下简化的代码段，但出现了一个错误：

from pymodbus.server.async import StartTcpServer, StopServer
from pymodbus.device import ModbusDeviceIdentification
from pymodbus.datastore import ModbusSequentialDataBlock
from pymodbus.datastore import ModbusSlaveContext, ModbusServerContext
from time import sleep

import logging
logging.basicConfig()
log = logging.getLogger()
log.setLevel(logging.DEBUG)

def main(name='Pymodbus'):
    store = ModbusSlaveContext(hr=ModbusSequentialDataBlock(0, [17]*100))
    context = ModbusServerContext(slaves=store, single=True)

    identity = ModbusDeviceIdentification()
    identity.VendorName = name
    identity.ProductCode = 'PM'
    identity.VendorUrl = 'http://github.com/bashwork/pymodbus/'
    identity.ProductName = 'Pymodbus Server'
    identity.ModelName = 'Pymodbus Server'
    identity.MajorMinorRevision = '1.0'

    StartTcpServer(
        context,
        identity=identity,
        address=("localhost", 5020),
        defer_reactor_run=True
    )
    sleep(3)
    name += 'stuff'

    StopServer()
    sleep(3)
    main(name)  # Recursive

main()

输出：

^{pr2}$

---

[更新]

另外，我尝试使用另一个线程来停止ModbusTcpServer，在ModbusTcpServer中使用defer_reactor_run=Flase参数（作为默认值），但即使这样，行为仍然保持不变：

import threading
import logging
from pymodbus.server.async import StartTcpServer, StopServer
from pymodbus.device import ModbusDeviceIdentification
from pymodbus.datastore import ModbusSequentialDataBlock
from pymodbus.datastore import ModbusSlaveContext, ModbusServerContext

logging.basicConfig()
log = logging.getLogger()
log.setLevel(logging.DEBUG)

def stop():
    StopServer()

def main(name='Pymodbus'):
    store = ModbusSlaveContext(hr=ModbusSequentialDataBlock(0, [17]*100))
    context = ModbusServerContext(slaves=store, single=True)

    identity = ModbusDeviceIdentification()
    identity.VendorName = name
    identity.ProductCode = 'PM'
    identity.VendorUrl = 'http://github.com/bashwork/pymodbus/'
    identity.ProductName = 'Pymodbus Server'
    identity.ModelName = 'Pymodbus Server'
    identity.MajorMinorRevision = '1.0'

    t = threading.Timer(5, stop)
    t.daemon = True
    t.start()

    StartTcpServer(
        context,
        identity=identity,
        address=("localhost", 5020),
        defer_reactor_run=False
    )
    name += 'stuff'

    main(name)  # Recursive

main()

输出：

INFO:pymodbus.server.async:Starting Modbus TCP Server on localhost:5020
DEBUG:pymodbus.server.async:Running in Main thread
DEBUG:pymodbus.server.async:Running in spawned thread
DEBUG:pymodbus.server.async:Stopping Server from another thread
INFO:pymodbus.server.async:Starting Modbus TCP Server on localhost:5020
DEBUG:pymodbus.server.async:Running in Main thread
Traceback (most recent call last):
  File "stack.py", line 41, in <module>
    main()
  File "stack.py", line 39, in main
    main()  # Recursive
  File "stack.py", line 35, in main
    defer_reactor_run=False
  File "/usr/local/lib/python3.6/dist-packages/pymodbus/server/async.py", line 257, in StartTcpServer
    reactor.run(installSignalHandlers=_is_main_thread())
  File "/usr/local/lib/python3.6/dist-packages/twisted/internet/base.py", line 1260, in run
    self.startRunning(installSignalHandlers=installSignalHandlers)
  File "/usr/local/lib/python3.6/dist-packages/twisted/internet/base.py", line 1240, in startRunning
    ReactorBase.startRunning(self)
  File "/usr/local/lib/python3.6/dist-packages/twisted/internet/base.py", line 748, in startRunning
    raise error.ReactorNotRestartable()
twisted.internet.error.ReactorNotRestartable

Answer 1

我找到了另一种解决方案，可以通过另一个Python代码来停止和启动异步ModbusTcpServer，因为显然，我们无法重新启动reactor事件循环。在

---

这是runner.py代码：

import subprocess

python_version = '3'
path_to_run = './'
py_name = 'async_server.py'

def run():
    args = [f"python{python_version}", f"{path_to_run}{py_name}"]
    sub_process = subprocess.Popen(args, stdout=subprocess.PIPE)
    output, error_ = sub_process.communicate()

    if not error_:
        print(output)
    else:
        print(error_)

    run()  # Recursively.

if __name__ == '__main__':
    run()

---

这是async_server.py代码段：

^{pr2}$

---

输出：

$ python3 runner.py 

2019-01-24 12:45:05,126 MainThread      INFO     async          :254      Starting Modbus TCP Server on localhost:5020
2019-01-24 12:45:10,129 Thread-1        DEBUG    async          :222      Running in spawned thread
2019-01-24 12:45:10,129 Thread-1        DEBUG    async          :332      Stopping Server from another thread
b'Start an async server.\nProcess will be down.\nServer was stopped.\n'
2019-01-24 12:45:13,389 MainThread      INFO     async          :254      Starting Modbus TCP Server on localhost:5020
2019-01-24 12:45:18,392 Thread-1        DEBUG    async          :222      Running in spawned thread
2019-01-24 12:45:18,392 Thread-1        DEBUG    async          :332      Stopping Server from another thread
b'Start an async server.\nProcess will be down.\nServer was stopped.\n'
2019-01-24 12:45:21,653 MainThread      INFO     async          :254      Starting Modbus TCP Server on localhost:5020
2019-01-24 12:45:26,656 Thread-1        DEBUG    async          :222      Running in spawned thread
2019-01-24 12:45:26,657 Thread-1        DEBUG    async          :332      Stopping Server from another thread
b'Start an async server.\nProcess will be down.\nServer was stopped.\n'
.
.
.

Answer 2

在第一个示例中，由于您将param defer_reactor_run设置为True，所以TCP服务器没有运行，但是您没有明确地运行它。因此，当您尝试停止它时，它会失败，因为它尚未启动。在

在第二个例子中，您运行它，但是下次使用main（name）调用递归地调用它！所以，它失败了，因为它已经启动了！ 下一个代码应该有效：

from pymodbus.server.async import StartTcpServer, StopServer
from pymodbus.device import ModbusDeviceIdentification
from pymodbus.datastore import ModbusSequentialDataBlock
from pymodbus.datastore import ModbusSlaveContext, ModbusServerContext
from time import sleep

import logging
logging.basicConfig()
log = logging.getLogger()
log.setLevel(logging.DEBUG)

def main(name='Pymodbus'):
    store = ModbusSlaveContext(hr=ModbusSequentialDataBlock(0, [17]*100))
    context = ModbusServerContext(slaves=store, single=True)

    identity = ModbusDeviceIdentification()
    identity.VendorName = name
    identity.ProductCode = 'PM'
    identity.VendorUrl = 'http://github.com/bashwork/pymodbus/'
    identity.ProductName = 'Pymodbus Server'
    identity.ModelName = 'Pymodbus Server'
    identity.MajorMinorRevision = '1.0'

    StartTcpServer(
        context,
        identity=identity,
        address=("localhost", 5020),
        defer_reactor_run=False
    )

    sleep(3)  # for the fun ?
    # and do your stuff 

    StopServer()

main()

如果要延迟运行，必须调用：

^{pr2}$