This USB Type-A to serial DB9 adapter with RS-232 tester by Delock combines two functions in one device. The RS-232 interface provides a connection for serial printers, measuring devices, machines etc. In addition, the nine LEDs in the connector provide simultaneous information on the status of the RS-232 data and the USB voltage supply. The RS-232 tester can be used for troubleshooting and helps to analyze the serial control and data lines.