// This example shows how to read 4 items from the device, and display their values, timestamps and qualities.
using System;
using System.Diagnostics;
using OpcLabs.EasyOpc.DataAccess;
using OpcLabs.EasyOpc.DataAccess.OperationModel;
namespace DocExamples.DataAccess._EasyDAClient
{
partial class ReadMultipleItems
{
public static void DeviceSource()
{
// Instantiate the client object.
var client = new EasyDAClient();
// DADataSource enumeration:
// Selects the data source for OPC reads (from device, from OPC cache, or dynamically determined).
// The data source (memory, OPC cache or OPC device) selection will be based on the desired value age and
// current status of data received from the server.
DAVtqResult[] vtqResults = client.ReadMultipleItems(
new []
{
new DAReadItemArguments("OPCLabs.KitServer.2", "Simulation.Random", DADataSource.Device),
new DAReadItemArguments("OPCLabs.KitServer.2", "Trends.Ramp (1 min)", DADataSource.Device),
new DAReadItemArguments("OPCLabs.KitServer.2", "Trends.Sine (1 min)", DADataSource.Device),
new DAReadItemArguments("OPCLabs.KitServer.2", "Simulation.Register_I4", DADataSource.Device)
});
for (int i = 0; i < vtqResults.Length; i++)
{
Debug.Assert(vtqResults[i] != null);
if (vtqResults[i].Succeeded)
Console.WriteLine("vtqResult[{0}].Vtq: {1}", i, vtqResults[i].Vtq);
else
Console.WriteLine("vtqResult[{0}] *** Failure: {1}", i, vtqResults[i].ErrorMessageBrief);
}
}
// Example output:
//
//vtqResult[0].Vtq: 0.00125125888851588 { System.Double} @2020-04-10T12:44:16.250; GoodNonspecific(192)
//vtqResult[1].Vtq: 0.270812898874283 {System.Double} @2020-04-10T12:44:16.248; GoodNonspecific(192)
//vtqResult[2].Vtq: 0.991434340167834 {System.Double} @2020-04-10T12:44:16.250; GoodNonspecific(192)
//vtqResult[3].Vtq: 0 {System.Int32} @1601-01-01T00:00:00.000; GoodNonspecific(192)
}
}
Rem This example shows how to read 4 items from the device, and display their values, timestamps and qualities.
Option Explicit
' Selects the data source for OPC reads (from device, from OPC cache, or dynamically determined).
' The data source (memory, OPC cache or OPC device) selection will be based on the desired value age and current status of
' data received from the server.
Const DADataSource_ByValueAge = 0
' OPC reads will be fulfilled from the cache in the OPC server.
Const DADataSource_Cache = 1
' OPC reads will be fulfilled from the device by the OPC server.
Const DADataSource_Device = 2
Dim ReadItemArguments1: Set ReadItemArguments1 = CreateObject("OpcLabs.EasyOpc.DataAccess.OperationModel.DAReadItemArguments")
ReadItemArguments1.ServerDescriptor.ServerClass = "OPCLabs.KitServer.2"
ReadItemArguments1.ItemDescriptor.ItemID = "Simulation.Random"
ReadItemArguments1.ReadParameters.DataSource = DADataSource_Device ' read will be from device
Dim ReadItemArguments2: Set ReadItemArguments2 = CreateObject("OpcLabs.EasyOpc.DataAccess.OperationModel.DAReadItemArguments")
ReadItemArguments2.ServerDescriptor.ServerClass = "OPCLabs.KitServer.2"
ReadItemArguments2.ItemDescriptor.ItemID = "Trends.Ramp (1 min)"
ReadItemArguments2.ReadParameters.DataSource = DADataSource_Device ' read will be from device
Dim ReadItemArguments3: Set ReadItemArguments3 = CreateObject("OpcLabs.EasyOpc.DataAccess.OperationModel.DAReadItemArguments")
ReadItemArguments3.ServerDescriptor.ServerClass = "OPCLabs.KitServer.2"
ReadItemArguments3.ItemDescriptor.ItemID = "Trends.Sine (1 min)"
ReadItemArguments3.ReadParameters.DataSource = DADataSource_Device ' read will be from device
Dim ReadItemArguments4: Set ReadItemArguments4 = CreateObject("OpcLabs.EasyOpc.DataAccess.OperationModel.DAReadItemArguments")
ReadItemArguments4.ServerDescriptor.ServerClass = "OPCLabs.KitServer.2"
ReadItemArguments4.ItemDescriptor.ItemID = "Simulation.Register_I4"
ReadItemArguments4.ReadParameters.DataSource = DADataSource_Device ' read will be from device
Dim arguments(3)
Set arguments(0) = ReadItemArguments1
Set arguments(1) = ReadItemArguments2
Set arguments(2) = ReadItemArguments3
Set arguments(3) = ReadItemArguments4
Dim Client: Set Client = CreateObject("OpcLabs.EasyOpc.DataAccess.EasyDAClient")
Dim results: results = Client.ReadMultipleItems(arguments)
Dim i: For i = LBound(results) To UBound(results)
Dim VtqResult: Set VtqResult = results(i)
If VtqResult.Succeeded Then
WScript.Echo "results(" & i & ").Vtq.ToString(): " & VtqResult.Vtq.ToString()
Else
WScript.Echo "results(" & i & ") *** Failure: " & VtqResult.ErrorMessageBrief
End If
Next