Help! - My New Computer Does Not Have Any COM Ports - What Do I Do Now?
Many new laptop (and some desktop) PCs are not shipped with any RS232 COM ports and instead they are equipped with USB ports. Because of this there is a great deal of confusion about how to handle the problem of connecting RS232 devices to the computer.

Why Can't I Plug An RS232 Device Into The USB Port?
The USB port on your PC is not at all similar to a RS232 COM port and it is not possible to have a Windows application program that is able to "open" a USB port and input data from it directly. All devices that connect to a USB port on a PC must either come with special "Device Driver" software that acts as the interface to the device or they must use one of the device drivers that are built into Windows. For example, many bar code scanners are now shipped with USB connectors so that you can connect the bar code scanner to the USB port on your PC. The way that most of them work is that when you plug the bar code scanner into the USB port on your PC, the scanner identifies itself to Windows as a "keyboard device" and instructs Windows to load the built in USB keyboard device driver that is normally shipped with Windows so that the bar code scanner will function as if it were a second keyboard connected to your PC. As far as Windows knows the bar code scanner is just another keyboard and when you scan a bar code, the data encoded in the bar code goes into the PC as if someone were typing it in on a keyboard.

Other devices that connect to a USB port may come with a Device Driver that you need to install. The problem with this is that any software that needs to communicate with the device will need to perform all data communications with the device through the device driver. In other words, you would not be able to use a standard "communications" program like the Hyperterminal program that comes with Windows or WinWedge from TALtech to read in data from the device. The only way to communicate with these types of USB devices would be to either develop custom software or be restricted to using whatever software the manufacturer of the device provides.

Because of this problem, many instrument manufacturers are staying with the RS232 serial interface as it is much more flexible than the USB interface and there is also a wide variety of off the shelf serial communications software products available that can be used to communicate with standard RS232 instruments.

The Solution To The Problem
If you have devices that connect to a PC using a standard RS232 serial port connection and your PC (laptop or desktop) does not have a RS232 serial port available, then the only real option is to purchase an add-on serial adapter that either gets plugged into a slot inside your PC or connects to a USB port (a USB add-on RS232 serial adapter). Both types of add-on serial adapter are readily available at any computer or office supply store.

The USB add-on serial adapters are the simplest to use. Basically they consist of a small cable with a USB connector on one side and a RS232 serial port connector on the other. The way that they work is that you first install a driver for the add-on USB serial adapter and then when you connect the adapter to the USB port on your PC, the driver creates a "virtual RS232 COM port" in Windows that is really a connection to the serial port on the add-on USB serial adapter. In other words, the add-on USB serial adapter appears to Windows as if it were a built in RS232 COM port and you can use any standard serial communications software to send and receive data through the add-on serial adapter just as if it were built into the motherboard of the PC. Single port add-on USB serial adapters generally sell for about $30.00. Multi-port USB add-on serial adapters are also available so that you can add as many RS232 serial ports as you like to a PC - all through a simple connection to the USB port.

One big advantage of the USB based add-on RS232 serial adapters is that you do not need to open the PC and insert a card into a card slot and you also do not need to worry about having any free resources like IRQs or port addresses because everything goes through the USB bus.

Summary
If your new computer does not have a built in COM port, get an USB add-on serial adapter from your local computer or office supply store, install the driver that comes with the adapter and plug it into the USB port. You will be able to use any standard RS232 serial communications software just like you did before when your PC had a built in COM port.

TAL Technologies, Inc., 2101 Brandywine Street, Suite 102, Philadelphia, PA 19130, USA.
215-496-0222 or 800-722-6004 (USA only). Fax: 215-496-0322.
Internet, www.taltech.com, e-mail: .