Cannot connect to Dynamixel XM430-W210-T by USB2Dynamixel adapter

[robomaniacpl]

Hello,

I have a problem with Dynamixel XM430-W210-T. I deliver power to Dynamixel via SMPS2Dynamixel and it is connected to USB2Dynamixel adapter. I set the adapter to TTL. Last time I could connect and control Dynamixel motor using Dynamixel Workbench software (http://wiki.ros.org/dynamixel_workbench) without any problem. Yesterday I tried to control the motor but the software couldn't find the dynamixel. I tried to connect with baud rate 57600 and 2.0 protocol version as before. Is there any approach to debug the dynamixel connection? Do you have an idea what can be wrong?

Best Regards

[jwatte]

First, hook up an oscilloscope to the TTL bus to make sure that the TTL UART signal is actually correctly generated.
If not, you need to debug the adapter, the USB drivers, and so forth.
Second, Try scanning with a different baud rate? 1000000, 2000000, 9600, and some other common baud rates?
Also, you could always try recovering the firmware on the servo, as that will typically reset the baud rates.

[robomaniacpl]

First, hook up an oscilloscope to the TTL bus to make sure that the TTL UART signal is actually correctly generated.
If not, you need to debug the adapter, the USB drivers, and so forth.
Second, Try scanning with a different baud rate? 1000000, 2000000, 9600, and some other common baud rates?
Also, you could always try recovering the firmware on the servo, as that will typically reset the baud rates.

Thank you very much for your response.

I checked the adapter with logic analyzer and it seems to be ok. I would like to point out that I could find and control this servo two weeks ago. Is it possible that the dynamixel could change baud rate by itself? Could you provide more info about recovering the firmware? I thought that I need to find and connect to the servo before recover its firmware.

Best Regards

[jwatte]

The firmware recovery in a tool like Dynamixel Manager uses a special fixed baud rate protocol that the servo starts out with when it powers on. This is why the recovery process is "first connect to the adapter, then power cycle the servo" -- the servo sends out a special "I'm starting up, is there recovery?" packet, which the adapter listens for. If it sees it, it responds back to the servo, and new firmware is uploaded, with a know fixed baud rate. If the servo doesn't see the response, it times out into regular configuration.