Answers.Body: <p>Summarizing our discussion from the comments:</p>
  <p>System is running Windows XP SP3 (not a VM) with an (unknown) USB to Serial converter connected to the <a href="https://www.bricklink.com/v2/catalog/catalogitem.page?P=x87#T=C" rel="nofollow noreferrer">Serial IR Tower</a>.</p>
  <p>Problem is that most interactions with the RCX are unsuccessful; Communication begins, but is typically interrupted partway through downloading programs to the brick.</p>
  <ol>
  <li>OP attempted suggestions from <a href="https://bricks.stackexchange.com/questions/10160/serial-tower-rcx-1-0-works-with-nqc-but-flakey-with-ris-2-0">this post</a>, with no luck.</li>
  <li>Tried a different RCX with no luck.</li>
  <li>Tried a different WinXP system with a built-in serial port and downloads were successful. Indicates the problem is with the USB to Serial converter.</li>
  </ol>
  <p>Conclusion: Not all USB to Serial converters are compatible with the Mindstorms Serial Tower. It is known that USB to Serial converters based on the PL2303 chipset work reliably, but this information is not always readily available. PL2303 has driver support for Windows 98 thru Windows 10, currently available for download <a href="http://www.prolific.com.tw/US/ShowProduct.aspx?p_id=223&amp;pcid=126" rel="nofollow noreferrer">here</a>.</p>
  
Answers.ContentLicense: CC BY-SA 4.0
Answers.CreationDate: 2022-02-21T16:00:51.127Z
Answers.LastActivityDate: 2022-02-21T16:00:51.127Z
Answers.UserDisplayName: MindS1
Body: <p>I'm new here. I used to use the old Mindstorms to teach robotics at a school back in early 2000s and I thought my grandson would like it, so I have bought an old second hand system. The RCX brick works and the tower is connected to the USB-serial port adapter. It says the RCX is working fine and will download 4 or 5 prog blocks. If I try more it tries but won’t download. Do you have any ideas?</p>
  
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-02-15T20:54:38.517Z
Comments.Text: I've encountered this issue before, but I'm not sure if I remember how I solved it. What OS are you using (and what usb-to-serial converter, if you have that info as well?)
  In the meantime try the suggestions here: https://bricks.stackexchange.com/questions/10160/serial-tower-rcx-1-0-works-with-nqc-but-flakey-with-ris-2-0
Comments.UserDisplayName: MindS1
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-02-16T09:02:56.860Z
Comments.Text: Thanks will look up info.
Comments.UserDisplayName: Jotec
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-02-16T10:15:51.573Z
Comments.Text: Thanks it is running on XP sp3. I have looked at your link but so far no progress. Additionally when I exit the software something remains as it will not reload saying only one copy of mindstorms can run.
Comments.UserDisplayName: Jotec
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-02-16T10:17:02.013Z
Comments.Text: Now failing to download built in progs!
Comments.UserDisplayName: Jotec
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-02-16T17:33:08.557Z
Comments.Text: Couple more questions for you:  1) Is this Windows XP running in a virtual machine?  2) Do you have access to a USB version of the IR tower?  3) It's possible the drivers for the USB to Serial converter are outdated, but the solution depends on its internal chipset. Mine uses the Prolific PL2303 chip, which has WinXP drivers [here](http://www.prolific.com.tw/US/ShowProduct.aspx?p_id=223&pcid=126).
Comments.UserDisplayName: MindS1
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-02-16T17:35:17.090Z
Comments.Text: Also try installing [BricxCC](https://sourceforge.net/projects/bricxcc/files/bricxcc/) which is a popular 3rd-party tool for interacting with the RCX. It supports the USB and Serial towers, and supposedly works more reliably than the default Lego software. See if you can download the firmware, control motors, download programs using this tool instead. Could help diagnose the issue.
Comments.UserDisplayName: MindS1
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-02-16T22:40:43.333Z
Comments.Text: Hi, the machine is an Xp not virtual. Hope to get another RCX on Friday to try the tower is serial running on usb converter I will try another converter. I have downloaded the bricxx but have not tried it yet as it is too much for the 8 yr old. Will give it a go.
Comments.UserDisplayName: Jotec
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-02-21T08:49:51.140Z
Comments.Text: Got an older Xp system and it all works fine on that so defiantly looks like it is the usb serial converter that is giving the problem  so I will sort out another converter and see if that fixes it.
Comments.UserDisplayName: Jotec
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-02-21T16:02:05.253Z
Comments.Text: Glad to hear it! My understanding is this is a fairly common issue, so I've summarized our discussion in the answers section so future people can benefit.
Comments.UserDisplayName: MindS1
Comments.ContentLicense: CC BY-SA 4.0
Comments.CreationDate: 2022-02-25T21:32:23.780Z
Comments.Text: The saga continues. I have acquired a usb tower. I thought this would solve the problem. I have installed it with the L tower software but the mindstorms still can’t find it. Any ideas?
Comments.UserDisplayName: Jotec
Tags: <rcx>
Title: RCX only accepts short programs
UserDisplayName: Jotec
ThreadText: # RCX only accepts short programs
  
  (Asked by: username_0 on 2022-02-15)
  
  I'm new here. I used to use the old Mindstorms to teach robotics at a school back in early 2000s and I thought my grandson would like it, so I have bought an old second hand system. The RCX brick works and the tower is connected to the USB-serial port adapter. It says the RCX is working fine and will download 4 or 5 prog blocks. If I try more it tries but won’t download. Do you have any ideas?
  
  **Tags:** rcx
  > **Comments:**
  > **username_1**: I've encountered this issue before, but I'm not sure if I remember how I solved it. What OS are you using (and what usb-to-serial converter, if you have that info as well?) In the meantime try the suggestions here: https://bricks.stackexchange.com/questions/10160/serial-tower-rcx-1-0-works-with-nqc-but-flakey-with-ris-2-0  
  > **username_0**: Thanks will look up info.  
  > **username_0**: Thanks it is running on XP sp3. I have looked at your link but so far no progress. Additionally when I exit the software something remains as it will not reload saying only one copy of mindstorms can run.  
  > **username_0**: Now failing to download built in progs!  
  > **username_1**: Couple more questions for you:  1) Is this Windows XP running in a virtual machine?  2) Do you have access to a USB version of the IR tower?  3) It's possible the drivers for the USB to Serial converter are outdated, but the solution depends on its internal chipset. Mine uses the Prolific PL2303 chip, which has WinXP drivers [here](http://www.prolific.com.tw/US/ShowProduct.aspx?p_id=223&pcid=126).  
  > **username_1**: Also try installing [BricxCC](https://sourceforge.net/projects/bricxcc/files/bricxcc/) which is a popular 3rd-party tool for interacting with the RCX. It supports the USB and Serial towers, and supposedly works more reliably than the default Lego software. See if you can download the firmware, control motors, download programs using this tool instead. Could help diagnose the issue.  
  > **username_0**: Hi, the machine is an Xp not virtual. Hope to get another RCX on Friday to try the tower is serial running on usb converter I will try another converter. I have downloaded the bricxx but have not tried it yet as it is too much for the 8 yr old. Will give it a go.  
  > **username_0**: Got an older Xp system and it all works fine on that so defiantly looks like it is the usb serial converter that is giving the problem  so I will sort out another converter and see if that fixes it.  
  > **username_1**: Glad to hear it! My understanding is this is a fairly common issue, so I've summarized our discussion in the answers section so future people can benefit.  
  > **username_0**: The saga continues. I have acquired a usb tower. I thought this would solve the problem. I have installed it with the L tower software but the mindstorms still can’t find it. Any ideas?  
  
  ---
  
  ## 1 answers
  
  ### Answer by username_1 on 2022-02-21. Score: 2
  
  Summarizing our discussion from the comments:
  
  System is running Windows XP SP3 (not a VM) with an (unknown) USB to Serial converter connected to the [Serial IR Tower](https://www.bricklink.com/v2/catalog/catalogitem.page?P=x87#T=C).
  
  Problem is that most interactions with the RCX are unsuccessful; Communication begins, but is typically interrupted partway through downloading programs to the brick.
  
  1. OP attempted suggestions from [this post](https://bricks.stackexchange.com/questions/10160/serial-tower-rcx-1-0-works-with-nqc-but-flakey-with-ris-2-0), with no luck.
  2. Tried a different RCX with no luck.
  3. Tried a different WinXP system with a built-in serial port and downloads were successful. Indicates the problem is with the USB to Serial converter.
  
  Conclusion: Not all USB to Serial converters are compatible with the Mindstorms Serial Tower. It is known that USB to Serial converters based on the PL2303 chipset work reliably, but this information is not always readily available. PL2303 has driver support for Windows 98 thru Windows 10, currently available for download [here](http://www.prolific.com.tw/US/ShowProduct.aspx?p_id=223&pcid=126).
  
  
  ---
  
  