protected void btReadTag_Click(object sender, EventArgs e)
{
if (String.IsNullOrEmpty(tbServerName.Text) || String.IsNullOrEmpty(tbTagName.Text))
{
liResult.Text = "OPC Server or tag name is invalid";
return;
}
OPCServer srv = new OPCServer(tbServerName.Text);
if (!srv.IsConnected)
{
liResult.Text = "Could not establish connection to OPC Server";
return;
}
OPCServerClient opcClient = new OPCServerClient(srv);
liResult.Text = String.Format("{0}: {1}", tbTagName.Text, opcClient.ReadTagVal(tbTagName.Text).ToString());
// Do not use in production code, it is only a demo.
// The connection to the OPC server should not be open and closed on each HTTP request
// It should only be opened once and kept in the user's session
// Disconnecting from the OPC must be handled inside the Session_End event
srv.Disconnect();
}
// Async method to send tags telemetry
private static async void SendDeviceToCloudMessagesAsync()
{
var opcDAServerUrl = ConfigurationManager.AppSettings["OPCDAServerUrl"];
OPCServer srv = new OPCServer(opcDAServerUrl);
Console.WriteLine(srv.ErrorMessage);
Console.WriteLine("Connected to OPCDA Server:" + srv.IsConnected);
OPCServerClient opcClient = new OPCServerClient(srv);
while (true)
{
// Create JSON message
var results = opcClient.ReadTagVal(ConfigurationManager.AppSettings["TagFileNamePath"]);
// Console.WriteLine("Number of tags data:" + results.Length);
foreach (var item in results)
{
var telemetryDataPoint = new
{
itemname = item.ItemName,
value = Convert.ToDouble(item.Value),
quality = item.Quality.ToString(),
timestamp = item.Timestamp
};
var messageString = JsonConvert.SerializeObject(telemetryDataPoint);
var message = new Message(Encoding.ASCII.GetBytes(messageString));
// Add a custom application property to the message.
// An IoT hub can filter on these properties without access to the message body.
// message.Properties.Add("temperatureAlert", (currentTemperature > 30) ? "true" : "false");
// Send the telemetry message
await s_deviceClient.SendEventAsync(message);
Console.WriteLine("{0} > Sending message: {1}", DateTime.Now, messageString);
}
await Task.Delay(Convert.ToInt32(ConfigurationManager.AppSettings["StreamInterval"]));
}
}