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Interfacing the CUWIN to Other Devices

The CUWIN has several different interfaces with which it can interface to other devices. In the exercises to follow we will make use of the Recommended Standard 232 (RS-232) interface, also known as a serial port or com port. We will use RS-232 to have the CUWIN communicate with a PC and the CUBLOC.


RS-232 has been around for many years and is commonly used in the HMI industry as a way for devices to communicate with one another. To illustrate how the CUWIN can use RS-232 to communicate with other devices, we will program the CUWIN to send messages to a PC.

The PC will display the received messages in HyperTerminal. HyperTerminal is an application included in all the latest versions of Windows, and is well-suited for RS-232 communication. Finally we will modify this program to read keystrokes in HyperTerminal and display them on the CUWIN.

Writing to the CUWIN's Serial Port

For this exercise, you will need to connect an RS-232 cable from CUWIN's COM1 serial port to a PC's serial port. The CUWIN and most PCs have more than one serial port, so be aware which serial port you are using. For this exercise, we will assume that both the CUWIN and the PC will use their COM1 serial port.

You should now have two connections between the CUWIN and the PC: USB and RS-232.

1. Create a new smart device project as we did for HelloWorld, and name it HelloHyperTerminal.

2. Make the project a “Device Application” just as we did for the HelloWorld project.

3. Add a large button to the form and label it “Say Hello” just as we did for the HelloWorld project

using System;
using System.ComponentModel;
using System.Windows.Forms;
using System.IO.Ports;
namespace HelloHyperTerminal
    public partial class Form1 : Form
        public Form1()
        private SerialPort _port;
        private void Form1_Load(object sender, EventArgs e)
            _port = new SerialPort("Com1",     //Com port
                                19200,         //Baud Rate
                                Parity.None,   //Parity
                                8,             //Data Bits
                                StopBits.One); //Stop Bits

4. Double-click in any blank space on the form, and Visual Studio will create a Form1_OnLoad event handler for you. Add code to this event handler exactly as pictured above.

5. Go back to the “Form1.cs [Design]” tab. Select the form, and in the “Properties” window click the lightning bolt icon . This will display all of the events that you can attach event handlers to. Double-click the Closing event and a Form1_Closing event handler will be created.

private void Form1_Closing(object sender, CancelEventArgs e)
    //Close the serial port

6. Add code to this event handler exactly as pictured above.

private void button1_Click(object sender, EventArgs e)
    //Send "Hello!" to HyperTerminal

7. Go back to the “Form1.cs [Design]” tab, and double-click the “Say Hello” button. This will add a button1_Click event handler. Add code to this event handler exactly as pictured above.

8. Finally adjust the project properties just as we did in the HelloWorld project

How the Code Works:

1. When the form opens, the form's Load event fires executing the Form1_Load event handler. This event handler configures the COM1 serial port and opens it so we can write to it.

2. When we close the form, the form's Closing event fires calling the Form1_Closing event handler. This event handler closes the COM1 serial port.

3. When we touch the “Say Hello” button, the button's Click event fires calling the button1_Click event handler. This event handler writes “Hello!” to the serial port. The “\r” and “\n” characters are a carriage return and line feed, so each “Hello!” we send appears on a new line.

Displaying our “Hello!” Message on the PC

We now need some device to read and display the “Hello!” being sent from the CUWIN. For this we will use the program HyperTerminal which is included in all recent versions of Windows.

1. Start HyperTerminal by selecting Start–>All Programs–>Accessories–>Communications–

HyperTerminal in the Windows start menu.

2. HyperTerminal will open and display a “Connection Description” dialog. It is here we need to configure the PC's serial port. Enter “CUWIN” in the “Name” textbox and click the “OK” button.

3. In the “Connect Using” drop-down list, select the serial port you wish to use. Note that this is the PC's serial port, not the CUWIN's serial port; they may be different. Then, click the “OK” button.

4. A new dialog will appear asking for your port settings. These settings must match those settings made in the Form1_Load event handler of the CUWIN program or the PC and the CUWIN will not be able to communicate with one another. Adjust the settings appropriately, then click the “OK” button.

5. Execute the CUWIN program from Visual Studio.

6. The form will display on the CUWIN. Click the “Say Hello” button.

7. Take a look at the PC's HyperTerminal window. You will see the “Hello!” message sent from the CUWIN.

cuwin/writing_to_the_cuwin_s_serial_port/index.txt · Last modified: 2016/04/14 11:07 (external edit)