iOptron USB to RS232 Converter

If your astronomy setup includes a mount with a serial (RS232) port but your laptop only has USB ports—as nearly all modern machines do—then this little cable becomes an essential part of your toolkit. The iOptron USB to RS232 Converter (#8435) bridges that generational gap, allowing you to communicate with your iOptron mount using planetarium software, firmware updates, or ASCOM/INDI control programs over a standard USB interface.

This converter features a USB Type-A plug on one end and a standard DB9 RS232 serial connector on the other, making it fully compatible with most iOptron mounts that utilize RS232 hand controller or mainboard ports. It’s plug-and-play with most modern operating systems and includes the Prolific chip driver—one of the most widely supported in the astronomy world.

Key Features:

• Connects USB-Only Devices to Serial RS232 Ports: Allows your modern computer to communicate with iOptron mounts or hand controllers that rely on RS232 serial input.

• High Compatibility: Designed for use with mounts like the CEM25P, SmartEQ Pro, CubePro, and older iOptron systems requiring serial communication.

• Reliable Prolific Chipset: Uses the Prolific PL2303 chipset for broad compatibility with Windows, macOS, and many Linux-based platforms. It’s the chipset most often recommended for astronomy applications.

• Plug and Play Functionality: In most cases, the converter is recognized automatically by your operating system, or drivers can be easily installed if needed.

• Standard DB9 Connector: Connects directly to the RS232 serial port on the mount or hand controller using a standard 9-pin configuration. For some mounts, a serial-to-RJ adapter may also be needed (sold separately).

Technical Specs:

• USB Connector: USB Type-A (standard male)

• Serial Connector: DB9 RS232 (male)

• Chipset: Prolific PL2303

• Cable Length: Approximately 36" (90 cm)

• Operating System Support: Windows 10/11, macOS, Linux (check Prolific’s site for current driver support)

Compatibility Notes:

This cable is intended for use with mounts that require serial (RS232) communication. Newer iOptron mounts such as the CEM40, GEM45, HAE, and HEM series typically use USB directly and do not need this adapter. Always check your mount’s control panel or hand controller port type before ordering.

Observing Tip:

If you're using older planetarium software or ASCOM drivers that require a COM port, this cable lets you set that up easily. Just make sure to check Device Manager (on Windows) or System Info (on Mac) to confirm which virtual COM port the adapter has assigned itself.