You may have a nine-pin port on the back of your TV, called an RS-232 serial port, or sometimes just a serial port. This same type of port is commonly used to connect a computer to a printer, but you’ve probably never used the RS-232 port on your TV. So, what is it actually used for?
The RS-232 standard is used specifically to transmit commands from one device to another. Unlike other ports on your TV, this has nothing to do with communicating audio or video signals. Its main purpose is to reliably control one or more TVs remotely via cable. Commercial businesses use RS-232 to automate digital panels or entire walls of displays because it is a simple, reliable serial communications standard that is also inexpensive on a large scale. Even though RS-232 is often considered the predecessor to USB, there are still many use cases where it is the most practical solution for displaying the same content on multiple displays at once.
There are also cases where the RS-232 port can be used to perform repair diagnostics or fix software bugs on smart TVs. For example, LG has provided documentation that technicians and advanced coders can follow when flashing software updates to faulty panels. This is another case where the RS-232 port is intended for professional use only; The idea that an average consumer should try to repair a TV with a DIY solution is one of the biggest tech repair myths you should stop believing.
Use your TV’s RS-232 port to automate your home
Your TV’s RS-232 serial port provides a viable way to integrate the display into a home automation system. You can even connect multiple devices with RS-232 ports to a computer or smart home controller running a home automation system, and take full advantage of your smart home by uniting your TV, projector, and audio system into one home theater environment.
However, manufacturers have cautioned that RS-232 functionality is not intended for use as part of the normal operation of consumer televisions. This means that there is no consumer-facing support for using the RS-232 port to automate your TV’s controls. While this shouldn’t necessarily stop you from moving forward with your home automation project, manufacturers recommend hiring a professional custom installer when implementing a custom integrated audio/video (A/V) system. Setting up your own automated home theater requires specific AV programming knowledge that you can’t learn in a quick crash course.
The RS-232 standard has been around since the 1960s, but you may have noticed that it’s becoming less and less common on modern TVs from brands like TCL. The TCL QM6K series is one of the best TVs for minimalists in 2026, but neither it nor its popular mid-range counterpart, the QM7K, has an RS-232 port. If you want to set up a home automation system that leverages a stable long-distance serial connection, you may need to shop around for a modern TV with an RS-232 port.