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();
}
