I've seen a few Mindstorms "infrared transmission towers" listed on Brick Owl, Bricklink and other sites. However, I cannot find any good documentation that how they work, how they are used by users, or why they exist.

Can someone shed some "light" on this for me?

2 Answers 2


IR Transmitter Tower exist in both USB version as well as Serial cable version.

Page 7 of instructions for one of the sets (3804) that was using USB version has following explanation:

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The IR Tower establishes a wireless link between your computer and the RCX. With the IR Tower, programs can be downloaded from computer to RCX. These programs can then be executed (run) by the RCX.

The IR Tower uses infrared signals to send messages.

For communication to occur, the RCX and IR Tower must be able to see each other. Even through 4-6 inches (10-12 cm) works best for downloading, in optimal lightning conditions, communication is still possible at distances up to 90 feet (30 meters) away.

To Download firmware to your RCX: Make sure your tower is plugged in and your RCX is turned on. Run the Robotics Invention System™ software and click the Settings button on the Main Menu. Click the button for downloading firmware.

Downloading takes approximately 4 minutes. The Software Watch counts as the firmware is downloading and will beep when it is done, do not switch off or move your RCX while downloading.

For more informations about setting up your RCX to work with your PC go to Settings.

And it also contains (rather obvious) picture of supposed use:

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  • 3
    I don't know about "supposed use", that's exactly how I used mine ;) The 1.0 set had a serial connection, while the 1.5 release had the newer USB version as I recall. It was the only way to get your programmes onto the brick, as there was no other connectivity options (unlike the NXT and EV3 with USB and Bluetooth, with the NXT also adding Wireless as well). Commented Jan 6, 2021 at 15:05
  • 1
    @Zhaph-BenDuguid Who knows, who knows... Some may want to have a challenge and bounce signal from couple of surfaces :)
    – Alex
    Commented Jan 6, 2021 at 17:58

Why they exist: to transmit programs from your computer to the Mindstorms smart brick (which is really another, probably smaller, computer). This was before USB ubiquity, and it also prevented children from plugging and unplugging a cable at the back of their computer, which is a dangerous move, even for adults.

  • I had a USB one. Not sure why they didn't put a USB-B port (or a custom connector) in the smart brick. Maybe it's so you can program robots without disassembling them. Commented Jan 6, 2021 at 18:22
  • That's almost definitely why. But the part was created before USB was really a thing you could count on. I remember those days well.
    – RSchulz
    Commented Jan 6, 2021 at 23:28
  • That's why it could be a custom connector. They could do a serial cable for serial, and a USB/serial cable for USB. Commented Jan 6, 2021 at 23:30
  • 1
    @user253751, serial can't be reliably hot-plugged. Usually it works, but sometimes it destroys the serial port.
    – Mark
    Commented Jan 6, 2021 at 23:32
  • @Mark then serial with opto-isolators in it. Commented Jan 6, 2021 at 23:42

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