def get_attribute(self, attr):
"""
Read one attribute of a node
result code from server is checked and an exception is raised in case of error
"""
rv = ua.ReadValueId()
rv.NodeId = self.nodeid
rv.AttributeId = attr
params = ua.ReadParameters()
params.NodesToRead.append(rv)
result = self.server.read(params)
result[0].StatusCode.check()
return result[0]
def get_attributes(self, attrs):
"""
Read several attributes of a node
list of DataValue is returned
"""
params = ua.ReadParameters()
for attr in attrs:
rv = ua.ReadValueId()
rv.NodeId = self.nodeid
rv.AttributeId = attr
params.NodesToRead.append(rv)
results = self.server.read(params)
return results
async def batch_load_fn(self, attributeKeys):
"""
Iterates through the attributeKeys and retrieves data
from OPC UA servers based on the attributeKey values.
Arguments
attributeKeys: List of strings with required infromation
to retrieve the attributes from OPC UA servers.
Template: "Server/NodeId/Attribute"
Example: "TestServer/ns=2;i=2/Value"
Results
sortedResults: List of values returned by the OPC UA server
for each attribute. Also includes OPC UA read
time with each attribute.
In same order as attributeKeys.
Example: [<opcua_object>, readTime]
"""
servers = defaultdict(list)
i = 0
for attribute in attributeKeys:
info = attribute.split("/")
servers[info[0]].append([i, info[1], info[2]])
i += 1
sortedResults = [None] * len(attributeKeys)
for serverName, attributes in servers.items():
params = ua.ReadParameters()
server = getServer(serverName)
for info in attributes:
rv = ua.ReadValueId()
if info[1] == "":
rv.NodeId = ua.NodeId.from_string(server.rootNodeId)
else:
rv.NodeId = ua.NodeId.from_string(info[1])
rv.AttributeId = ua.AttributeIds[info[2]]
params.NodesToRead.append(rv)
results, readTime = await server.read(params)
i = 0
for info in attributes:
sortedResults[info[0]] = [results[i], readTime]
i += 1
return sortedResults
async def get_variable_nodes(self,
node,
nodeClass=2,
variableList=None,
depth=0,
maxDepth=10):
"""
Eats a list of node object(s).
Recursively finds nodes under given nodes that have given nodeClass.
Returns node objects in a list.
"""
if variableList is None:
variableList = []
depth += 1
if depth >= maxDepth:
return variableList
nodes = node.get_children()
params = ua.ReadParameters()
for node in nodes:
rv = ua.ReadValueId()
rv.NodeId = node.nodeid
rv.AttributeId = ua.AttributeIds.NodeClass
params.NodesToRead.append(rv)
results = []
if len(params.NodesToRead) > 0:
results, readTime = await self.read(params)
for i in range(len(results)):
if nodeClass == results[i].Value.Value:
variableList.append(nodes[i])
await self.get_variable_nodes(node=nodes[i],
nodeClass=nodeClass,
variableList=variableList,
depth=depth)
return variableList
def __init__(self, server, nodeid):
self.server = server
self.nodeid = nodeid
self.params = ua.ReadParameters()
self._debug_attr = []
