// This example shows how to read a Low state of a limit alarm. Note that you should not normally read a state of an alarm
// from inside its event notification, because the state might have already changed. Instead, include the information you
// need in the Select clauses when subscribing for the event.
using System;
using OpcLabs.EasyOpc.UA;
using OpcLabs.EasyOpc.UA.AddressSpace;
using OpcLabs.EasyOpc.UA.Navigation;
namespace UADocExamples.AlarmsAndConditions
{
class ReadAlarmState
{
public static void Main1()
{
UAEndpointDescriptor endpointDescriptor =
"opc.tcp://opcua.demo-this.com:62544/Quickstarts/AlarmConditionServer";
UANodeDescriptor alarmNodeDescriptor = new UANodeId(
namespaceUriString:"http://opcfoundation.org/Quickstarts/AlarmCondition",
identifier:"1:Colours/EastTank?Yellow");
// Knowing the alarm node, and the fact that is an instance of NonExclusiveLevelAlarmType (or its subtype),
// determine what is its LowState/Id node.
UANodeDescriptor lowStateIdNodeDescriptor = new UABrowsePath(alarmNodeDescriptor,
new []
{
UABrowsePathElement.CreateSimple("ns=0;s=LowState"),
UABrowsePathElement.CreateSimple("ns=0;s=Id")
});
// Instantiate the client object.
var client = new EasyUAClient();
Console.WriteLine("Reading alarm state...");
var lowStateId = (bool)client.ReadValue(endpointDescriptor, lowStateIdNodeDescriptor);
Console.WriteLine($"Id of LowState: {lowStateId}");
}
}
}
# This example shows how to read a Low state of a limit alarm. Note that you should not normally read a state of an alarm
# from inside its event notification, because the state might have already changed. Instead, include the information you
# need in the Select clauses when subscribing for the event.
# The QuickOPC package is needed. Install it using "pip install opclabs_quickopc".
import opclabs_quickopc
import time
# Import .NET namespaces.
from OpcLabs.EasyOpc.UA import *
from OpcLabs.EasyOpc.UA.AddressSpace.Standard import *
from OpcLabs.EasyOpc.UA.AlarmsAndConditions import *
from OpcLabs.EasyOpc.UA.OperationModel import *
def eventNotification(sender, eventArgs):
print()
# Display the event.
if eventArgs.EventData is None:
print(eventArgs)
return
baseEventObject = eventArgs.EventData.BaseEvent
print('Source name: ', baseEventObject.SourceName, sep='')
print('Message: ', baseEventObject.Message, sep='')
print('Severity: ', baseEventObject.Severity, sep='')
# Define which server we will work with.
endpointDescriptor = UAEndpointDescriptor('opc.tcp://opcua.demo-this.com:62544/Quickstarts/AlarmConditionServer')
# Instantiate the client object and hook events.
client = EasyUAClient()
client.EventNotification += eventNotification
print('Subscribing...')
IEasyUAClientExtension.SubscribeEvent(
client,
endpointDescriptor,
UANodeDescriptor(UAObjectIds.Server),
1000)
print('Processing event notifications for 30 seconds...')
time.sleep(30)
print('Unsubscribing...')
client.UnsubscribeAllMonitoredItems()
print('Waiting for 5 seconds...')
time.sleep(5)
print('Finished.')
