Some devices will only connect to your computer using a port called "RS232 Serial Port". This port was used on old computers before 2003.

RS232 was the universal/popular port back in the old days just like USB is today.

In short, all you need to know is...

Modern computers no longer have RS232 port (extinct just like VGA port is). So all you need to get is a RS232-to-USB converter. It's about $5 on eBay. Just search for: rs232 usb

When you buy it, you'll need to install it to Windows-based computer. Here's how...

Step 1:

Connect RS232 device into any USB port on your laptop/computer. Allow 20+- seconds for Windows to attempt to install drivers automatically.

If it's successful, skip to Step 2 below.

However in 95% of cases, it will fail to automatically install the drivers. So you have to install drivers manually.

Here's how...

1) Disconnect RS232 device from your computer.

2) Install both driver packs below...

         - Driver Pack 1
         - Driver Pack 2
         - Driver Pack 3

3) Restart your computer.

4) Connect RS232 device into any USB port. This time Windows will auto-install the drivers. You can verify a correct install going to Device Manager. Here's how...

Windows Vista/7/8/10:

Control Panel » System » Device Manager

Windows XP:

Control Panel » System » "Hardware" tab » Device Manager

 

You should see something like this:

 

If install STILL failed to install the drivers or above "Prolific..." device has a yellow triangle next to it, then: Install the driver file from the disc that came with the RS232 Device.

 

Step 2:

Verify RS232 device is connected to COM PORT number between 1 to 4. This is a MUST, else it will not work.

Here's how to do this...

Right-click on "Prolific..." device in Device Manager and click on "Properties". As seen below. Then: Click: Port Settings Click: Advanced For "COM Port Number" — choose any number between 1-4. That's it! It's now working 100% as it should.