Answers.Body: <p>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.</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-01-06T23:28:09.327Z
Answers.Text: 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.
Answers.UserDisplayName: RSchulz
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-01-06T23:32:58.647Z
Answers.Text: @user253751, serial can't be reliably hot-plugged.  Usually it works, but sometimes it destroys the serial port.
Answers.UserDisplayName: Mark
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-01-05T21:16:31.733Z
Answers.LastActivityDate: 2021-01-05T21:16:31.733Z
Answers.UserDisplayName: RSchulz
Answers.Body: <p>IR Transmitter Tower exist in both <a href="https://www.bricklink.com/v2/catalog/catalogitem.page?P=x431c01#T=C" rel="noreferrer">USB version</a> as well as <a href="https://www.bricklink.com/v2/catalog/catalogitem.page?P=x87#T=C" rel="noreferrer">Serial cable version</a>.</p>
  <p>Page 7 of <a href="https://www.lego.com/cdn/product-assets/product.bi.core.pdf/4157492.pdf" rel="noreferrer">instructions</a> for one of the sets (<a href="https://www.bricklink.com/v2/catalog/catalogite-0m.page?S=3804-1" rel="noreferrer">3804</a>) that was using USB version has following explanation:</p>
  <p><a href="https://i.sstatic.net/ZfFi5.png" rel="noreferrer"><img src="https://i.sstatic.net/ZfFi5.png" alt="enter image description here" /></a></p>
  <p><a href="https://i.sstatic.net/BhwFE.png" rel="noreferrer"><img src="https://i.sstatic.net/BhwFE.png" alt="enter image description here" /></a></p>
  <p>Transcription:</p>
  <blockquote>
  <p>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.</p>
  <p>The IR Tower uses infrared signals to send messages.</p>
  <p>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.</p>
  <p>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 <strong>Settings</strong> button on the Main Menu. Click the button for downloading firmware.</p>
  <p>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.</p>
  <p>For more informations about setting up your RCX to work with your PC go to Settings.</p>
  </blockquote>
  <p>And it also contains (rather obvious) picture of supposed use:</p>
  <p><a href="https://i.sstatic.net/Ccb2i.png" rel="noreferrer"><img src="https://i.sstatic.net/Ccb2i.png" alt="enter image description here" /></a></p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-01-06T15:05:27.813Z
Answers.Text: 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).
Answers.UserDisplayName: Zhaph - Ben Duguid
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-01-06T17:58:09.723Z
Answers.Text: @Zhaph-BenDuguid Who knows, who knows... Some may want to have a challenge and  bounce signal from couple of surfaces :)
Answers.UserDisplayName: Alex
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2021-01-05T22:09:23.893Z
Answers.LastActivityDate: 2021-01-05T22:21:50.570Z
Answers.LastEditDate: 2021-01-05T22:21:50.570Z
Answers.UserDisplayName: Alex
Body: <p>I've seen a few Mindstorms &quot;infrared transmission towers&quot; listed on <a href="https://www.brickowl.com/catalog/lego-infrared-transmission-tower-set-9713" rel="noreferrer">Brick Owl</a>, <a href="https://www.bricklink.com/v2/catalog/catalogitem.page?id=10759" rel="noreferrer">Bricklink</a> and other sites. However, I cannot find any good documentation that how they work, how they are used by users, or why they exist.</p>
  <p>Can someone shed some &quot;light&quot; on this for me?</p>
  
Tags: <part-identification><mindstorms><electronics>
Title: How do the Infrared Towers work?
UserDisplayName: EJ Mak
ThreadText: # How do the Infrared Towers work?
  
  (Asked by: username_0 on 2021-01-05)
  
  I've seen a few Mindstorms "infrared transmission towers" listed on [Brick Owl](https://www.brickowl.com/catalog/lego-infrared-transmission-tower-set-9713), [Bricklink](https://www.bricklink.com/v2/catalog/catalogitem.page?id=10759) 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?
  
  **Tags:** part-identification, mindstorms, electronics
  
  
  ---
  
  ## 2 answers
  
  ### Answer by username_3 on 2021-01-05. Score: 9 | Accepted answer
  
  IR Transmitter Tower exist in both [USB version](https://www.bricklink.com/v2/catalog/catalogitem.page?P=x431c01#T=C) as well as [Serial cable version](https://www.bricklink.com/v2/catalog/catalogitem.page?P=x87#T=C).
  
  Page 7 of [instructions](https://www.lego.com/cdn/product-assets/product.bi.core.pdf/4157492.pdf) for one of the sets ([3804](https://www.bricklink.com/v2/catalog/catalogite-0m.page?S=3804-1)) that was using USB version has following explanation:
  
  [![enter image description here](https://i.sstatic.net/ZfFi5.png)](https://i.sstatic.net/ZfFi5.png)
  
  [![enter image description here](https://i.sstatic.net/BhwFE.png)](https://i.sstatic.net/BhwFE.png)
  
  Transcription:
  
  > 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:
  
  [![enter image description here](https://i.sstatic.net/Ccb2i.png)](https://i.sstatic.net/Ccb2i.png)
  
  > **Comments:**
  > **username_4**: 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).  
  > **username_3**: @username_4-BenDuguid Who knows, who knows... Some may want to have a challenge and  bounce signal from couple of surfaces :)  
  
  ---
  
  ### Answer by username_1 on 2021-01-05. Score: 3
  
  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.
  
  > **Comments:**
  > **username_1**: 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.  
  > **username_2**: @user253751, serial can't be reliably hot-plugged.  Usually it works, but sometimes it destroys the serial port.  
  
  ---
  
  