如何停止 pymodbus 异步 ModbusTcpServer？答案

【问题标题】：How to stop a pymodbus async ModbusTcpServer?如何停止 pymodbus 异步 ModbusTcpServer？
【发布时间】：2019-06-15 22:18:00
【问题描述】：

我想停止 pymodbus async ModbusTcpServer 然后启动一个新服务器。因此，我尝试使用以下简化代码 sn-p，但出现错误：

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：

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 42, in <module>
    main()
  File "stack.py", line 38, in main
    StopServer()
  File "/usr/local/lib/python3.6/dist-packages/pymodbus/server/async.py", line 328, in StopServer
    reactor.stop()
  File "/usr/local/lib/python3.6/dist-packages/twisted/internet/base.py", line 630, in stop
    "Can't stop reactor that isn't running.")
twisted.internet.error.ReactorNotRunning: Can't stop reactor that isn't running.

[更新]

另外，我尝试在另一个线程中使用defer_reactor_run=False 参数（默认）在ModbusTcpServer 中停止ModbusTcpServer，但尽管如此，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

【问题讨论】：

您找到解决方法了吗？
@kaptan 实际上，我并没有寻求找到解决该问题的原始方法。但是，我记得我用另一种解决方案绕过了它，并将其作为答案发送。

标签： python python-3.x twisted reactor pymodbus

【解决方案1】：

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

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sn-p：

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

import threading
import sys
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)

def stop():
    print('Process will be down.')
    StopServer()  # Stop server.
    sys.exit(0)  # Kill the server code.

def run_async_server():
    store = ModbusSlaveContext(hr=ModbusSequentialDataBlock(0, [17] * 100))
    slaves = {
        0x01: store,
        0x02: store,
        0x03: store,
    }
    context = ModbusServerContext(slaves=slaves, single=False)

    identity = ModbusDeviceIdentification()
    identity.VendorName = 'Pymodbus'
    identity.ProductCode = 'PM'
    identity.VendorUrl = 'http://github.com/bashwork/pymodbus/'
    identity.ProductName = 'Pymodbus Server'
    identity.ModelName = 'Pymodbus Server'
    identity.MajorMinorRevision = '1.5'

    from twisted.internet import reactor
    StartTcpServer(context, identity=identity, address=("localhost", 5020),
                   defer_reactor_run=True)
    print('Start an async server.')
    t = threading.Timer(5, stop)
    t.daemon = True
    t.start()
    reactor.run()
    print('Server was stopped.')

if __name__ == "__main__":
    run_async_server()

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'
.
.
.

【讨论】：

【解决方案2】：

在第一个示例中，TCP 服务器没有运行，因为您将 param defer_reactor_run 设置为 True，但您没有明确运行它。因此，当您尝试停止它时，它会因为尚未启动而失败。

在第二个示例中，您运行它，但下次使用 main(name) 调用递归调用它！所以，它失败了，因为它已经开始了！下一个代码应该可以工作：

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()

如果你想推迟运行，你必须调用：

from twisted.internet import reactor
StartTcpServer(context, identity=identity, address=("localhost", 5020),
            defer_reactor_run=True)
reactor.run()

【讨论】：

在第二个例子中，我使用 pymodbus 中的内置 StopServer() 在 5 秒后通过另一个线程停止反应器
也许可以，但同时您尝试在计时器唤醒之前重新启动已经启动的服务器。
试过这个sn-p代码了吗？此代码卡在StartTcpServe() 中，因为defer_reactor_run 为假。但是，我想停止并重新启动服务器
它没有卡住，它运行一个服务器....如果你想停止它，杀死任务。我更新了如何在延迟模式下运行它
我的问题很明显，这不是我的答案，感谢您的回复。

【解决方案3】：

您可以使用库文件夹中包含的示例：asynchronous-server.py

在 python3.7 中 async 被包含为关键字，但在 pymodbus 2.3.0 中 pymodbus.server.async 被更改为 pymodbus.server.asynchronous

我分享一个适合我的例子：

如果您还有任何问题，请发邮件给我：Danielsalazr@hotmail.com

#Este codigo funciona ingresando a la direccion esclavo 16 en decimal
#la Ip debe ser la misma que esta asignada en el dispositivo

#los datos se actualizan a patir del registro #15
#Aparentemente la direcion del esclavo no tiene importancia, debido a que
#al realizar la conexion desde el software QModMaster, el numero ingresado
#em el campo SlaveAddr, no afecta la posibilidad de conexion

'''
Pymodbus Server With Updating Thread
--------------------------------------------------------------------------

This is an example of having a background thread updating the
context while the server is operating. This can also be done with
a python thread::

    from threading import Thread

    thread = Thread(target=updating_writer, args=(context,))
    thread.start()
'''
#---------------------------------------------------------------------------# 
# import the modbus libraries we need
#---------------------------------------------------------------------------# 
from pymodbus.server.asynchronous import StartTcpServer
from pymodbus.device import ModbusDeviceIdentification
from pymodbus.datastore import ModbusSequentialDataBlock
from pymodbus.datastore import ModbusSlaveContext, ModbusServerContext
from pymodbus.transaction import ModbusRtuFramer, ModbusAsciiFramer

#---------------------------------------------------------------------------# 
# import the twisted libraries we need
#---------------------------------------------------------------------------# 
from twisted.internet.task import LoopingCall

#---------------------------------------------------------------------------# 
# configure the service logging
#---------------------------------------------------------------------------# 
import logging
logging.basicConfig()
log = logging.getLogger()
log.setLevel(logging.DEBUG)

#---------------------------------------------------------------------------# 
# define your callback process
#---------------------------------------------------------------------------# 
def updating_writer(a):
    ''' 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")
    context  = a[0]
    register = 3
    slave_id = 0x01
    address  = 0x10
    values   = context[slave_id].getValues(register, address, count=5)
    #el valor count = 5 modifica los datos de los siguientes 5 registros
    #continuos al registro especificado en la variable address = 0x10, 16 en decimal
    values   = [v + 1 for v in values]
    log.debug("new values: " + str(values))
    context[slave_id].setValues(register, address, values)

#---------------------------------------------------------------------------# 
# initialize your data store
#---------------------------------------------------------------------------# 
store = ModbusSlaveContext(
    di = ModbusSequentialDataBlock(0, [17]*100),
    co = ModbusSequentialDataBlock(0, [17]*100),
    hr = ModbusSequentialDataBlock(0, [17]*100),
    ir = ModbusSequentialDataBlock(0, [17]*100))
context = ModbusServerContext(slaves=store, single=True)

#ModbusSlaveContext.setValues("lol",hr,3,25)
#context = ModbusServerContext(slaves=store, single=True)
#---------------------------------------------------------------------------# 
# initialize the server information
#---------------------------------------------------------------------------# 
identity = ModbusDeviceIdentification()
identity.VendorName  = 'pymodbus'
identity.ProductCode = 'PM'
identity.VendorUrl   = 'http://github.com/bashwork/pymodbus/'
identity.ProductName = 'pymodbus Server'
identity.ModelName   = 'pymodbus Server'
identity.MajorMinorRevision = '1.0'

#---------------------------------------------------------------------------# 
# run the server you want
#---------------------------------------------------------------------------# 
time = 1 # 5 seconds delay
loop = LoopingCall(f=updating_writer, a=(context,))
loop.start(time, now=False) # initially delay by time
StartTcpServer(context, identity= identity, address=("192.168.0.40", 502)) #here you need 
#change the ip for the ip address of your device

来自哥伦比亚的问候

【讨论】：

您好 Daniel，由于该 pymodbus 库已更新，pymodbus.server.async 已在较新版本中转换为 pymodbus.server.asynchronous，我知道（我的问题被问了一年以前使用 pymodbus 的早期版本）。然而，这不是我的问题。正如我在问题中提到的，问题是StopServer 而不是StartTcpServer