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  1. Red face Sync_write to multiple servos

    Hello everyone,

    lately I've been trying to build a small robot using multiple XL-320 servos. I am currently using a OpenCM9.04 as a serial tosser while sending the packets from the PC via USB. I ran into some issues using the sync_write functionality in Dynamixel SDK. When commanding 9 servos, modified sdk example sync_write.cpp works just fine. Whenever i attempt to command 10+ servos at once, the packet is sent but the servos do not move nor respond to any other communication and the board needs to be reset.

    Has any of you run into a similar problem? I'm not really sure where exactly the problem is or how to fix it. I've already tried to loosen the LATENCY_TIMER in port_handler_linux.cpp in Dynamixel SDK, but it didn't work.

    Thank you for any replies


  2. #2

    Re: Sync_write to multiple servos

    Is the problem in the servos, or with the board/sketch?
    Is this a buffer overflow problem in the "serial tosser" code?
    If you hook up a scope/logic analyzer to the servo TTL bus, does the 10+ sync_write command make it onto the bus?

  3. Re: Sync_write to multiple servos

    Hello, thank you for your reply. I have solved this issue already. There was a problem with the serial tosser code, just as you said

  4. #4

    Re: Sync_write to multiple servos

    As @jwatte implied, hard to know without having a better understanding of your setup.

    Things like: I assume you are using Arduino setup with the OpenCM9.04. What version? Have you updated it to the latest stuff?

    In cases like this it would help to see your sketch or at least the specific parts of it to understand what is going on.

    I know there are/were some issues with Syncwrite and the like that were sort of hard coded for max and min setups... It was worse with Dynamixel Workbench... Some of these I put fixes into, which were taken up with Robotis. Some have not yet been.

    I will be trying out some of this also soon with 18 servos XL430 servos, So will see if I run into same issue.

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