Subscribing to PLC data via code
VB Example:
The AdvancedHMI drivers support a subscription that will automatically poll data and return the values. The DataSubscriber provides a non-code method of using this service. However, there are times when it is desired or more efficient to subscribe using code. This is an example on how to do this:
Private SubscriptionID1 As Integer
Private Sub Button2_Click_1(sender As Object, e As EventArgs) Handles Button2.Click
SubscriptionID1 = EthernetIPforCLXCom1.Subscribe("MyTag", 1, 500, AddressOf Subscription_DataReceived)
End Sub
Private Sub Subscription_DataReceived(sender As Object, e As Drivers.Common.PlcComEventArgs)
If e.ErrorId=0 AndAlso e.Values IsNot Nothing AndAlso e.Values.Count>0 Then
Label1.Text = e.Values(0)
End If
End Sub
Private Sub MainForm_FormClosing(sender As Object, e As FormClosingEventArgs) Handles Me.FormClosing
EthernetIPforCLXCom1.UnSubscribe(SubscriptionID1)
End Sub
The rate at which data is polled is determined by the value of the PollRateOverride property.
Each driver is highly optimized for communications using subscriptions. All of the visual controls (e.g. Gauge) use the subscription mechanism to receive their data.
C# Example:
The Following is an example of how to programmatically set the comm drivers and create subscriptions to PLC addresses using the "DataSubscriber2" control. The "DataSubscriber2" runs on a background thread which allows for asynchronous capability when gathering tag information.
using AdvancedHMIDrivers;
using AdvancedHMIControls;
using MfgControl.AdvancedHMI.Drivers;
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
//
namespace AdvancedHMICS
{
public partial class MainForm : Form
{
#region Initalize Comms & Properties
// Always have 3 Comm Drivers (Slow, Medium, and Fast)
// It doesn't slow down your application because this all runs on a background thread
// and the comms drivers poll from the same datalink layer
EthernetIPforSLCMicroCom CommSlowDewaxer1 = new EthernetIPforSLCMicroCom();
EthernetIPforSLCMicroCom CommMediumDewaxer1 = new EthernetIPforSLCMicroCom();
EthernetIPforSLCMicroCom CommFastDewaxer1 = new EthernetIPforSLCMicroCom();
//
// The following variables set the properties of the comms above in the project
string CommDewaxerIPAddress = "192.168.10.1";
int CommDewaxerSlow = 1000; // polling every second
int CommDewaxerMedium = 500; // polling every half second
int CommDewaxerFast = 200; // polling every 200 milliseconds
#endregion
//
#region DataSubscribers
bool initalizeSub = false;
// Dewaxer 1 Slow Subscriber
DataSubscriber2 DataSlowDewaxer1 = new DataSubscriber2();
DataSubscriber2 DataMediumDewaxer1 = new DataSubscriber2();
DataSubscriber2 DataFastDewaxer1 = new DataSubscriber2();
//
// NOTE: There are two different examples of adding elements programmatically
//
// Example 1
// This is one way of adding individual tags to the data subscriber during creation of the project
// and then adding these items to the subscriber in the form
PLCAddressItem Dewaxer1Temperature = new PLCAddressItem("N7:10",1,"D1Temp","Dewax 1 Temperature",1,1);
PLCAddressItem Dewaxer2Temperature = new PLCAddressItem("N7:11", 1, "D2Temp", "Dewax 2 Temperature", 1, 1);
//
// Example 2
// This is the other way. Create an array of a set number and then add in the form
PLCAddressItem[] DewaxerSlow = new PLCAddressItem[1]; // 2 item array (0 index)
#endregion
//
public MainForm()
{
InitializeComponent();
//
#region Set Comm & Subscriber Properties & Items
if (initalizeSub == false)
{
#region Set IP Addresses, Poll Rates, And Subscription Comms
// Dewaxer Comms
CommSlowDewaxer1.IPAddress = CommDewaxerIPAddress;
CommSlowDewaxer1.PollRateOverride = CommDewaxerSlow;
//
CommMediumDewaxer1.IPAddress = CommDewaxerIPAddress;
CommMediumDewaxer1.PollRateOverride = CommDewaxerMedium;
//
CommFastDewaxer1.IPAddress = CommDewaxerIPAddress;
CommFastDewaxer1.PollRateOverride = CommDewaxerFast;
//
// Bind Dewaxer Data Subscribers to Comms
DataSlowDewaxer1.ComComponent = CommSlowDewaxer1;
DataMediumDewaxer1.ComComponent = CommMediumDewaxer1;
DataFastDewaxer1.ComComponent = CommFastDewaxer1;
#endregion
//
#region DataSubscribers (Continuation)
// Check to see if subscriptions have been initalized
// Example 1
DataSlowDewaxer1.PLCAddressValueItems.Add(Dewaxer1Temperature);
DataSlowDewaxer1.PLCAddressValueItems.Add(Dewaxer2Temperature);
//
// Example 2
DewaxerSlow[0].PLCAddress = "N7:0"; // Actual Address or tag name in the processor
DewaxerSlow[0].Description = "Example";
DewaxerSlow[0].Name = "Test"; //
DewaxerSlow[0].ScaleOffset = 2; // This will offset the PLC value by plus 2 (NOTE: may use this if a sensor value is reading constantly offset)
DewaxerSlow[0].ScaleFactor = .50; // This will divide the PLC value by half (NOTE: may use this if you have to convert to a percentage)
//
DewaxerSlow[1].PLCAddress = "N7:2";
DewaxerSlow[1].Description = "Example2";
DewaxerSlow[1].Name = "Test2";
DewaxerSlow[1].ScaleOffset = 2;
DewaxerSlow[1].ScaleFactor = .50;
//
for (var i = 0; i < DewaxerSlow.Count(); i++)
{
DataSlowDewaxer1.PLCAddressValueItems.Add(DewaxerSlow[i]);
}
// Subscriptions have been initalized
initalizeSub = true;
#endregion
}
#endregion
}
//
#region DataSubscribers (Set Data)
#region Slow Subscriptions
private void DataSlowDewaxer1_DataChanged(object sender, MfgControl.AdvancedHMI.Drivers.Common.PlcComEventArgs e)
{
if (e.ErrorId == 0)
{
if (e.PlcAddress == "N7")
{
// map the value of this
// lbl_example.Text = e.Values[0];
}
}
}
#endregion
#region Medium Subscriptions
private void DataMediumDewaxer1_DataChanged(object sender, MfgControl.AdvancedHMI.Drivers.Common.PlcComEventArgs e)
{
if (e.ErrorId == 0)
{
if (e.PlcAddress == "N7")
{
// map the value of this
// lbl_example.Text = e.Values[0];
}
}
}
#endregion
#region Fast Subscriptions
private void DataFastDewaxer1_DataChanged(object sender, MfgControl.AdvancedHMI.Drivers.Common.PlcComEventArgs e)
{
if (e.ErrorId == 0)
{
if (e.PlcAddress == "N7")
{
// map the value of this
// lbl_example.Text = e.Values[0];
}
}
}
#endregion
#endregion
}
}
