5 genuinely useful ways to use the serial port on the back of your TV

Published Jul 18, 2026, 8:00 AM EDT Adam has a degree in Engineering and has a life-long interest in technology. He has been writing for over a decade for various print and online publications, with a focus on consumer tech. He joined How-To Geek in 2024 while working at Pocket-lint. As well as being a long-term fan of Apple products, he also has a strong interest in smart home tech, running a Home Assistant server at home to automate all his smart home devices. He believes that the ideal smart home should work with minimal interaction from the user, with automations running as if by magic rather than requiring you to push buttons on a control panel. You can find more of his work on Muck Rack. If you look at the back of your TV, there are many ports that you probably never use. Some older TVs include an RS-232 serial port similar to those that you'd find on the back of old PCs. While the main uses of this port include professional diagnostics and servicing, there are several ways you can use your TV's serial port for other things. Read the TV's current state Know the state of the TV for certain Credit: Adam Davidson / How-To Geek I've been controlling my TV using smart home software for more than a decade. I started off relying solely on an IR blaster that could send the same signals as my infrared TV remote. Over time, more and more functionality has been taken over by other methods, such as using dedicated smart TV integrations in Home Assistant. I still use IR to control my TV, as it's not easy to get my TV to power on reliably from standby using smart home integrations. To get my TV to turn on, I use the IR blaster to send out the same signal as my remote control sends when I press the power button. The problem with IR is that it doesn't always work. If something is blocking the TV when the signal sends from the IR blaster, the TV doesn't turn on. My smart home thinks that the TV is on, however, since the signal to turn it on has been sent. It can cause automations to stop working correctly. Home Assistant has now added support for ESPHome serial proxies, so you can connect an ESP32-based RS-232 proxy to your TV and control it through the serial port if your TV supports serial commands. Not only does this make the TV power on more reliably, but you can also poll the state of the TV to determine for certain whether it's on, what the volume level is, which input is being used, and more, making automations rock solid. USB Type C to RS232 DB9 Serial Port Adapter Brand OIKWAN Cable Type USB-C A USB-C to RS-232 cable adapter that alllows a modern PC to communicate with older hardware or industrial systems. Length 6ft/10ft Data Transfer Rate 1Mbps USB Version USB 2.0 Wake a TV from standby Serial control can fix deep sleep problems Credit: Tim Brookes / How-To Geek Another benefit of using the serial port on the back of your TV is that it can wake the TV from standby. Some TVs can be woken using Wake-on-LAN commands, but these can sometimes fail when the TV goes into deep sleep. The TV's network interface may be unreachable, so the power-on command fails. By sending signals through the serial port, you can bypass the TV's sleeping network interface. If your TV supports serial wake commands in standby, sending the appropriate command through the serial port can wake the TV and power it on, removing one of the most frustrating issues of TV automations. Turn on the TV when the PC wakes up Reliably wake your TV Credit: Ismar Hrnjicevic / How-To Geek You can use a TV as a monitor for your PC, whether you're gaming or using your PC as your home theater source. Most of the time things work fine, but you can experience problems trying to get your TV to turn on when the PC wakes. While a standard monitor may power on correctly when the PC wakes, your TV may refuse to do so, since this isn't its primary intended purpose. Some users have managed to use the serial port to solve this problem. Using a simple script on your PC, you can send a signal through the serial port telling your TV to power on whenever your PC wakes up. This means that when you wake your computer, your TV will automatically turn on too. Switch inputs when devices become active No more manual HDMI input selection HDMI-CEC can make selecting the right inputs for your TV a little easier. When I power up my PS5, for example, my TV automatically switches to the correct HDMI input. However, I have more HDMI devices than ports, so I use an HDMI switcher for other devices such as my Nintendo Switch 2. Using my HDMI switcher, HDMI-CEC doesn't work, so when I power on my Switch, the TV doesn't change to the appropriate input. Using the serial port, you can send commands to switch to specific inputs, so it's possible to create automations that will switch to the correct input when you power on a device, even when HDMI-CEC can't manage it. Use a TV as an information display Show dashboards or images on the TV Credit: Bertel King / How-To Geek Your TV is probably the biggest screen in your home, but it often only gets put to use for a fraction of the day. You can use your TV to do more than just watch shows and movies. For example, you can use a TV to display smart home dashboards, family calendars, weather information, security camera feeds, or photo slideshows. While the serial port doesn't allow you to display content directly (you'll need to do this through the usual video inputs, such as HDMI), it does allow you to control when your TV turns on, which input it displays, and how loud the volume is. You can have your TV turn on at a set time, switch to the input that displays your smart home dashboard, mute the volume, and then turn everything off again at a specific time. Don't sleep on your TV's ports Many of the ports on the back of your TV can feel a little pointless, such as serial ports, USB ports, or optical audio ports. There may be more you can do with them than you realize.