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Thread: Not Able to Find AX-12A servo with Dynamixel Wizard

  1. Not Able to Find AX-12A servo with Dynamixel Wizard

    Hi,

    I am an absolutely newbie here and I am trying to use Dynamixel Wizard to test my AX-12A servo through USB2Dynamixel, but I cannot find the servo ID using either DXL 1.0 or DXL 2.0.

    I am able to see that USB2Dynamixel is connecting to COM3, and I have already unplug the connection between the servo that I am testing against and the rest of the servo. I am using the Dynamixel Wizard that come with RoboPlus, and I am using Windows10.

    Does anyone know what's going on?

  2. #2

    Re: Not Able to Find AX-12A servo with Dynamixel Wizard

    How are you powering the servo?

    Do you have the switch on the USB2DYNAMIXEL set to 'TTL'?

  3. Re: Not Able to Find AX-12A servo with Dynamixel Wizard

    I am using the 12V5A power supply that came with the package and I just double checked the switch on USB2Dyn is set to TTL. The Dynamixel also flash once with red LED light (I learned from some other posts that this is normal). I even tried to do a firmware recovery but Dyn Wizard still cannot find the Dynamixel so I cannot perform firmware recovery.

    I am guessing my wiring is incorrect, here are 2 pictures that shows my current configuration:
    https://drive.google.com/file/d/0Bzw28vh4UqJ7ckthZTZaMzVYUU5RSDN1UHhFSVJxb19yZVpv/view?usp=sharing
    https://drive.google.com/file/d/0Bzw28vh4UqJ7aXlUR01DRHVVLWpqSU5UOEF5bU1DX0JtMmhr/view?usp=sharing

    Sincerely

  4. #4

    Re: Not Able to Find AX-12A servo with Dynamixel Wizard

    Do you have a multimeter? (Or an oscilloscope, or a small logic analyzer?)
    If so, measure that you have ground and power on the right pins on the USB2Dynamixel and (if you have the oscilloscope/analyzer) that you see the TTL bus signa.
    Unfortunately, if you got the wiring wrong, it's possible that you have burned the input on the AX12 or the output on the USB2Dynamixel.

  5. Re: Not Able to Find AX-12A servo with Dynamixel Wizard

    I just used an oscilloscope and confirmed that the power is indeed supplying 12V to the servo, and I can see signal port is showing about 5V when I do a search on Dynamixel Wizard, so the output from USB2Dyn is fine. How do I confirm the input on AX12A is OK? also is there a way to send command to AX12A directly so that I know it is responding?

    Sincerely

  6. #6

    Re: Not Able to Find AX-12A servo with Dynamixel Wizard

    Sorry, I am repeating several things above, but things I would check:

    1) again make sure set to ttl. Make sure the baud rate is set to 1mbs... You only have one servo connected.

    2) Make sure you have 12 volts going to the servo

    3) again verify that the servo blinks once when you plug it in.

    4) When you try doing firmware recovery, you unplug the servo and then plug it in, just as it tries to find the servo. Been awhile since I have done a recovery, but I believe doing that makes sure the servo starts up in default mode such that the recovery system can try to talk to servo.

    5) Do you have a 2nd servo to try?

  7. #7

    Re: Not Able to Find AX-12A servo with Dynamixel Wizard

    A fine command to send to a servo is a WRITE command for the LED register (0x19) to value 1, using the BROADCAST servo address (0xFE)
    That will make all servos on the bus turn on their LEDs if communication works and the baud rate is correct.

  8. Re: Not Able to Find AX-12A servo with Dynamixel Wizard

    I tried with another servo and it is showing the same. How can I issue a command from my laptop to the servo without USB2Dyn?

    by the way when I was searching for dynamixels from dynamixel wizard I see something weird, the text showing when searching says "Searching... 1000000 mbps DXL2.0" even when I am selecting DXL1.0. But I think my AX12A is using DXL1.0, is this a problem? Please see the print screen below:
    https://drive.google.com/file/d/0Bzw...ew?usp=sharing

    Sincerely

  9. #9

    Re: Not Able to Find AX-12A servo with Dynamixel Wizard

    It starts doing that always (for me too) but then goes on to search for the dynamixels.

    Have you tried a firmware reset using the USB2Dynamixel? If that doesn't work, then the USB2Dxl or the AX12a have broken communications circuits.
    If you have an oscilloscope, setting it to show the signal between TTL-out and ground, and trigger on falling waveform, should show a clear serial line at 1 MHz base frequency, when searching at 1 Mbps communication speed.

  10. #10
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    Re: Not Able to Find AX-12A servo with Dynamixel Wizard

    Quote Originally Posted by chenji28 View Post
    I tried with another servo and it is showing the same. How can I issue a command from my laptop to the servo without USB2Dyn?

    by the way when I was searching for dynamixels from dynamixel wizard I see something weird, the text showing when searching says "Searching... 1000000 mbps DXL2.0" even when I am selecting DXL1.0. But I think my AX12A is using DXL1.0, is this a problem? Please see the print screen below:
    https://drive.google.com/file/d/0Bzw...ew?usp=sharing

    Sincerely
    You said in your original post that it was connecting on COM3, and your screenshot shows you're searching on COM23. Are you sure you're searching the right COM port?

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