async def read_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 = await self.server.read(params)
result[0].StatusCode.check()
return result[0]
async def read_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 = await self.server.read(params)
return results
async def read_attribute(self, attr, indexrange=None):
"""
Read one attribute of a node
attributeid is a member of ua.AttributeIds
indexrange is a NumericRange (a string; e.g. "1" or "1:3".
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
rv.IndexRange = indexrange
params = ua.ReadParameters()
params.NodesToRead.append(rv)
result = await self.server.read(params)
result[0].StatusCode.check()
return result[0]
