If your computer is equipped with a 9-pin COM port and you have a cable from a device with a 25-pin connector for the COM port, you can use this small adapter to solve the problem. Plug the adapter into the port to convert it directly to a 25-pin COM port.
Sandberg Adapter COM 9F-25M
Sandberg Adapter COM 9F-25M. Gender: Male/female, Connector(s): COM 9F-25M, Adapter type: COM. Color of product: White. Width: 0" (0 mm), Depth: 0" (0 mm), Height: 0" (0 mm). Package width: 0.335" (8.5 mm), Package depth: 0.0787" (2 mm), Package height: 0.492" (12.5 mm)