So simple question about file descriptor

USB chained mode so I can simply use ttyACM0 port only.

Sorry, I was editing my post while you were responding:

Do you see channel 0 moving at all if you watch it in the control center when running this program?

Can you control channel 0 from the Control Center?


Not at all…
In the status tab, I tried changing target and speed with the slider, I can see the green ball is moving but i don’t really see the physical movement of the servo I connected.

Am i supposed to see movement if i play with the slider in the control center??


If you do not see the green ball moving when setting positions with a serial command, then that command is not working properly, and you should debug that first, before adding any read() code.

One problem is that you are trying to set the servo to a 1460/4 = 365 us, which is way out of the default range. Can you try setting it to 6000 instead? We give the exact bytes “0x84, 0x00, 0x70, 0x2E” for this in the Maestro User’s Guide, so I think you should start with that exact command until you get it working.

How are you powering your servos?


Hi Paul!
We had a power problem as well so the servo moves perfectly !!!

Thank you for your and your companies’ advices and help!!

One more question though.
we played with the servo on the control center so we can check what min and max target value I need to know
for the proper control over it.

It seems that the servo stops moving between min 750 and max 2250. I tested even smaller and larger number, the servo pretty much stopped around the values.

However, we noticed that, after we pulled off the servo from the board, there were still some extra space to the actual min and max position of the servo.

How can I make the servo all the way to the min and max? is that something I have to do on the servo programmer since we are using digital servo?

Please let me know.
Thank you =]


If it is a digital servo, it might have some built-in logic to prevent it from hitting the limit. Some digital servos have a special programmer that you can buy to reprogram the internal limits, but that would depend on exactly what servo you have.

Please be careful not to break the servo!