POST No. 2407697
XH430-W350 Encoder Not remembering last known position
2019-12-12 19:19:41 RT_XD0


I am currently in possession of several Dynamixel XH430-W350 servos which I am using to drive mechanical arm components.

I am having problems with the servo where it will not remember the last position it was at after it is turned off.

For example:

When the servo turns on, I would tell it to go to position 5095. I then turn the servo off and then back on again and I can see that the position of the servo is around 1000 (-360 degrees from previous value) even though I did not tell it to move. I saw this using the Dynamixel U2D2 tool, in the R+ Manager software.

I have seen this on several different servos and not just on 1 of them. Is this because there is a firmware setting which is causing this to happen?

Firmware version: 43

Baud rate: 4M

Mode of operation: Extended Position mode.

Power: 12V

Communication: U2D2 and R+ Manager.

Thank you in advance for helping me out! Please feel free to ask me further questions if there is any confusion.

Best Regards,


2019-12-12 19:19:41
2019-12-13 01:48:08 Will Son


Thank you for your inquiry.

Please note that when using Extended Position Control Mode, the internal turn count will be reset when mode is changed or power is turned off.

Thank you.

2019-12-13 01:48:08
2019-12-13 18:42:09 RT

Hi Willson,

Thanks for the reply! I understand now why this is happening. I thought this might be the case, but I did not see any mention of the internal turn count being reset in the datasheet. 

Thanks again,


2019-12-15 16:47:03 willson
Hi RT,
I'll make sure to revise the documentation to clarify this feature.
Happy holidays!
2019-12-15 16:47:03
2019-12-13 18:42:09
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