Python-OPC-UA将变量传递给UA方法

Question

我有一个例子，其中一个方法被添加到服务器空间。该示例设置为获取两个输入值并将它们相加

代码示例

from opcua import Server, ua, uamethod, instantiate
import time
from opcua.ua import NodeId, NodeIdType

@uamethod
def add_func(self, a, b):
    print("Adding parameters:\n", a, "\tand\t", b)
    return a + b

if __name__ == "__main__":

    # setup server
    server = Server()
    server.set_endpoint("opc.tcp://localhost:4840") #alternative: 
    server.set_endpoint("opc.tcp://0.0.0.0:4840")
    server.set_server_name("Server example")
    server.set_security_policy([ua.SecurityPolicyType.NoSecurity])
    uri = "http://example.uri.de"
    idx = server.register_namespace(uri)
    
    # get Objects node, this is where we should adress our custom stuff to
    objects = server.get_objects_node() # alternative: root_node = server.get_root_node()
    
    # add structure to the namespace (idx) below the Objects node
    myobj = objects.add_object(idx, "MyObject")

    # add variables, type can be defined by assigning a value or ua Variant Type definition
    var1 = myobj.add_variable(idx, "var1", 321, ua.VariantType.Int64)
    var2 = myobj.add_variable(idx, "var2", 123, ua.VariantType.Int64)

    # set variables writable for clients (e.g. UaExpert)
    var1.set_writable()
    var2.set_writable()

    # set input arguments for method
    input_arg1 = ua.Argument() # create new argument
    input_arg1.Name = "a" # name for argument
    input_arg1.DataType = ua.NodeId(ua.ObjectIds.Int64) # data type
    input_arg1.ValueRank = -1 # value rank to be treated a scalar number
    input_arg1.Description = ua.LocalizedText("First integer a") # add description text

    input_arg2 = ua.Argument()
    input_arg2.Name = "b"
    input_arg2.DataType = ua.NodeId(ua.ObjectIds.Int64)
    input_arg2.ValueRank = -1
    input_arg2.Description = ua.LocalizedText("Second integer b")

    # set output arguments
    output_arg = ua.Argument()
    output_arg.Name = "Result"
    output_arg.DataType = ua.NodeId(ua.ObjectIds.Int64)
    output_arg.ValueRank = -1
    output_arg.Description = ua.LocalizedText("Sum")

    print(var1.nodeid)
    print(var2.nodeid)

    # add method to namespace
    mymethod = myobj.add_method(idx, "MyAddFunction", add_func, [input_arg1, input_arg2], [output_arg])

    server.start()

我想做的更改是删除输入参数并自动接受var1&；调用MyAddFunction时将var2作为输入。 我使用UaExpert调用此方法。 UaExpert when calling MyAddFunction

我尝试通过使用变量的NodeID传递变量，如下所示：

mymethod = myobj.add_method(idx, "MyAddFunction", add_func, [var1.nodeid, var1.nodeid], [output_arg])

并获取以下错误消息： opcua.ua.uaerrors.\u base.UaError:NodeId:无法猜测NodeId的类型，请设置NodeId类型

创建变量时是否未定义类型？ 采用var1&；的方法需要做哪些更改；var2作为输入参数？是否有方法将这些值分配给创建的输入参数（input_arg1和input_arg2）

提前谢谢你！ 问候南多