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Expansion Hub Serial Addresses ***IMPORTANT MESSAGE***

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  • Expansion Hub Serial Addresses ***IMPORTANT MESSAGE***

    Hi Folks,

    For teams who are using multiple Expansion Hubs, it is important that the serial address of each device (used to distinguish one Expansion Hub from another) be different. FIRST has discovered recently that teams should not use a value of 1 for an Expansion Hub's serial address, unless that Expansion Hub is part of a REV Robotic's Control Hub.

    Although the FTC software apps allow you to select a value of 1 for any Expansion Hub, when assigning a serial address to an Expansion Hub, it is not recommended that you use this address because the FTC software assumes that an Expansion Hub with a serial address of 1 is part of a REV Robotics Control Hub (see http://www.revrobotics.com/REV-31-1152/). Note that Control Hubs are currently not approved for use in the FIRST Tech Challenge.

    FIRST recommends that if you are using two Expansion Hubs for your robot, that you make sure they have different serial addresses, and that their values are anything other than 1.

    Note that we have not noticed in our long term testing any issues due to using a standalone Expansion Hub with an address of 1. However, if you do have an Expansion Hub with the address set to 1, we recommend that you change its address and then retest your robot to make sure your Control System wasn't disrupted by the change.

    Details on how to set the address of your Control System can be found here:

    https://github.com/ftctechnh/ftc_app...Expansion-Hubs

    Also, after you have changed the serial address, you might have to reconfigure the Configuration file for your robot to reflect the change in the device's serial number.

    Again, I would like to reiterate that in spite of this warning, we have not noticed any apparent issues when running an Expansion Hub with the serial address of 1. However, in order to be proactive and avoid any potential issues, we recommend that teams avoid using address #1 for now.

    Finally, some people were concerned that this serial address issue was causing the "Stuck USB write" error messages that some teams have been encountering. Currently, we do NOT believe that this USB communication error is caused by this serial address issue. We have credible reports that teams have seen this "Stuck USB write" errors for robots that were using a single Expansion Hub, with that single Hub's address set to the default value of 2. Presently, we do NOT believe that the "Stuck USB write" errors are caused by a team using a serial address of 1.

    I apologize for any confusion or frustration this might have caused teams. Note that the developers are working on a fix that will remove the assumption from the FTC software that an Expansion Hub with an address of 1 is part of a Control Hub.

    Tom
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