Update server configuration from client

[francescobianca]

What's the best way to add nodes using an OPC-UA Client?

I have my parent node:
sensors_node = await parent.get_child(["Sensors"])

and i want to add another sensor, something like this:
await sensors_node.add_object(0, id, type)

but from the client this code doesn't work (The same inside the server works).

Any suggestions?

Thanks

[oroulet]

what error? If you have the rights to create nodes it should work. might be though, because I have not yet seen a server allowing you to do that

[francescobianca]

Hi @oroulet

From the client I selected the parent and printed all the children (1 at the time of the initial configuration). Now from the client I wanted to add a second (sensor2) (as seen from the code). But this node is not created -> always prints i = 0 and it is wrong.

[DEBUG] --------- Children before ---------
[DEBUG] Sensor with code i=20036 and name LocalizedText(Locale=None, Text='sensor1')
[DEBUG]
[DEBUG] New sensor: i=0
[DEBUG]
[DEBUG] ------- Children after -------
[DEBUG] Sensor with code i=20036 and name LocalizedText(Locale=None, Text='sensor1')

Also, if I try to access it, it returns an error:

temp = await sensors_node.add_object(0, id, type)
logger.debug(f"New sensor: {temp}")
logger.debug(f"New sensor name: {await temp.read_display_name()}")

[DEBUG] New sensor: i=0
[ERROR] "The node id refers to a node that does not exist in the server address space."(BadNodeIdUnknown)

[AndreasHeine]

opcua-asyncio/asyncua/client/ua_client.py

Line 580 in 8631c0a

async def add_nodes(self, nodestoadd):

[francescobianca]

Yes is a self programmed server (opcua-asyncio lib).

Maybe is more correct to define CRUD methods inside server and call them from the client?

[AndreasHeine]

sure ua methods are great for crud!

[francescobianca]

I have defined this method in the server (starting from a base example):

@uamethod
async def add_node(parent, parent_node, id_sensor, type_sensor):
    # print("multiply method call with parameters: ", x, y)
    logger.info(f"Method with params: parent_node: {parent_node}, id_sensor: {id_sensor} and type_sensor: {type_sensor}")
    # await parent_node.add_object(0, id_sensor, type_sensor)
    return 2 * 2

methods = await self.server.nodes.objects.add_object(self.idx, "Methods")
await methods.add_method(self.idx, "add_node", add_node,
                         [ua.VariantType.ExtensionObject, ua.VariantType.Int64, ua.VariantType.Int64],
                         [ua.VariantType.Int64])

and call this from Client:

obj = await client.nodes.root.get_child(["0:Objects", "2:Methods"])
res = await obj.call_method("2:add_node", sensors_node, id_sensor, types[model_sensor])

but this is wrong. ([ERROR] 'Node')

sensors_node is a <class 'asyncua.common.node.Node'> object --> How should it be defined in the method header?

[AndreasHeine]

the 100% correct way is to pass "ua.Argument"-Clases instead of [ua.VariantType.ExtensionObject, ua.VariantType.Int64, ua.VariantType.Int64]

don't understand what you is meant with "method header" -> the method parameters?

[AndreasHeine]

the order of the arguments is the order of the method parameters!
and for the client-side i wrote some examples a while ago: https://github.com/AndreasHeine/opcua-tutorial/blob/main/client/call_method.py