How to Find a Serial Port Address

Steps to find the address of a serial port.

Serial ports were once used for most external devices on computers. Eventually, the older 9-pin and 25-pin serial ports were replaced by much faster USB connections. Traditional COM ports can run at a maximum of 115 Kbps, whereas the original USB 1.0 specification ran at 11 Mbps. There are still situations today where serial ports are used, especially with Point of Sale systems. In these situations it is useful to know which addresses the serial ports are using.

Instructions

1. Right-click on "My Computer."

2. Click "Manage."

3. Click "Device Manager."

4. Click the plus sign next to "Ports (COM & LPT)."

5. Look for any devices that say "Communications Port" and note the "COM" number after it. In all but special cases, this is either "COM1" or "COM2." This is the address of the serial port. Double-click the COM port entry, then click the "Resources" tab to view additional important information such as the IRQ and I/O Address Range.

Tips & Warnings

• Each serial port can be reconfigured to use a different COM address by double-clicking the COM port entry in the Device Manager.