freeopcua install

from https://stackoverflow.com/questions/43360587/opc-ua-server-client-on-raspberry-pi2

sudo apt-get update
sudo apt-get install libxml2-dev libxmlsec1-dev libffi-dev
pip install cryptography
pip install freeopcua

from https://github.com/FreeOpcUa/freeopcua

Example minimal client in python

  client = opcua.Client(False)
  client.connect("opc.tcp://10.10.10.4:4841/OPCUA/AnyServer/")

  objects = client.get_objects_node()
  print("Children of objects are: ", objects.get_children())

  var = objects.get_child(["3:AnObject", "AVariable"])
  print("Value of variable is: ", var.get_value())
  
  client.disconnect()

from https://github.com/huazh/python-opcua/blob/master/examples/example-client.py
python-opcua/examples/example-client.py

  

	import sys
	sys.path.insert(0, "..")
	import logging
	import time
	try:
	from IPython import embed
	except ImportError:
	import code
	def embed():
	vars = globals()
	vars.update(locals())
	shell = code.InteractiveConsole(vars)
	shell.interact()
	from opcua import Client
	from opcua import ua
	class SubHandler(object):
	"""
	Subscription Handler. To receive events from server for a subscription
	data_change and event methods are called directly from receiving thread.
	Do not do expensive, slow or network operation there. Create another
	thread if you need to do such a thing
	"""
	def datachange_notification(self, node, val, data):
	print("Python: New data change event", node, val)
	def event_notification(self, event):
	print("Python: New event", event)
	if __name__ == "__main__":
	logging.basicConfig(level=logging.WARN)
	#logger = logging.getLogger("KeepAlive")
	#logger.setLevel(logging.DEBUG)
	client = Client("opc.tcp://localhost:4840/freeopcua/server/")
	# client = Client("opc.tcp://admin@localhost:4840/freeopcua/server/") #connect using a user
	try:
	client.connect()
	# Client has a few methods to get proxy to UA nodes that should always be in address space such as Root or Objects
	root = client.get_root_node()
	print("Root node is: ", root)
	objects = client.get_objects_node()
	print("Objects node is: ", objects)
	# Node objects have methods to read and write node attributes as well as browse or populate address space
	print("Children of root are: ", root.get_children())
	# get a specific node knowing its node id
	#var = client.get_node(ua.NodeId(1002, 2))
	#var = client.get_node("ns=3;i=2002")
	#print(var)
	#var.get_data_value() # get value of node as a DataValue object
	#var.get_value() # get value of node as a python builtin
	#var.set_value(ua.Variant([23], ua.VariantType.Int64)) #set node value using explicit data type
	#var.set_value(3.9) # set node value using implicit data type
	# Now getting a variable node using its browse path
	myvar = root.get_child(["0:Objects", "2:MyObject", "2:MyVariable"])
	obj = root.get_child(["0:Objects", "2:MyObject"])
	print("myvar is: ", myvar)
	# subscribing to a variable node
	handler = SubHandler()
	sub = client.create_subscription(500, handler)
	handle = sub.subscribe_data_change(myvar)
	time.sleep(0.1)
	# we can also subscribe to events from server
	sub.subscribe_events()
	# sub.unsubscribe(handle)
	# sub.delete()
	# calling a method on server
	res = obj.call_method("2:multiply", 3, "klk")
	print("method result is: ", res)
	embed()
	finally:
	client.disconnect()

from https://hant.helplib.com/GitHub/article_111897

python 中的最小客戶端示例

 client = opcua.Client(False)
 client.connect("opc.tcp://10.10.10.4:4841/OPCUA/AnyServer/")
 objects = client.get_objects_node()
 print("Children of objects are:", objects.get_children())
 var = objects.get_child(["3:AnObject","AVariable"])
 print("Value of variable is:", var.get_value())
 client.disconnect()