POST No. 2406695
How to use XM430-W350-R(torque control)
2018-02-12 01:36:17 hayato1728

Dear Robotis Support 

I use “Dynamixel (XM430-W350-R)”. I would like to use this Dynamixel for controlling force of a gripper.I use the program of read_write.m of MATLAB of Dynamixel SDK (Version 3.X).I changed this program a little.I would like to control the torque.

But I do not know how to do that.

For example, I will run "write2ByteTxRx(port_num, PROTOCOL_VERSION, DXL_ID, Goal_Current, 10)".

Can you tell me How much current does is represented by figure 10?

And, how much is the torque?

Could you give me a sample program for torque control?


I look forward to hearing from you.

2018-02-12 01:36:17
2018-02-12 09:36:08 Will Son


The Goal Current value can be converted into the actual current by multiplying 2.69mA to the value.

So if you write 10 to Goal Current, it can be seen to output 26.9mA.

Although Current vs Torque conversion constant is not provided, you can use Performance Graph to figure out the Output Torque(N.m) from Current(A) by reading red linear line.

For example, if you write 111 to Goal Current, it will be converted to 111*2.69mA = 298.59mA.

In the performance graph, you can find 0.3 A at the right column and it will generate about 0.35 Nm at the output horn.

The current limit for XM430-W350 is 1193, however, the stall current is 2.3A so it is recommended to use lower than 20% of the stall current during normal use for the best life cycle.

2018-02-12 09:36:08
2018-02-12 23:59:49 Hayato

Thank you very much for your kind instruction。

I learned to read the torque from the performance graph。

However、I have a new question。

If I write 10(10 * 2.69 mA = 0.0269 A)、the torque will be a negative value calculated from the performance graph。

However、the motor is operating normally。

If the current value is small、can not calculate the torque?

2018-02-12 23:59:49
2018-02-13 08:54:56 Will Son

The Current vs Torque graph is a trend graph.

If you need to rotate to other direction, use negative value to the Goal Current.

Positive Goal current will always try to move to the positive direction.

If the current is too small, it is difficult to read the precise torque.

In that case, it might be better to use your own torque measuring equipment.

Thank you for your inquiry.

2018-02-13 08:54:56
2018-02-13 17:27:09 Hayato

Thank you so much!

I would like to try it with a little more current.

2018-02-13 17:27:09
2018-02-14 16:41:42 Will Son


Let us know if you need help :)

2018-02-14 16:41:42
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