AX-12+ Return delay time

[Fritzoid]

I'm trying to extract position feedback data from the 18 dynamixels connected to my CM-510 (Bioloid Premium kit).

At 1Mb, you can clock out the 8 bytes of a read packet in 72us and receive 8 bytes back in another 72us. However, the typical dynamixel is setup to pause for 500us between receiving the packet and transmitting the response. Robotis says that the return delay time can be set as low as 1us. A setting this low could easily improve throughput by a factor of 4. Thus the controller could read the position data from 50 or more servos within the firmware heartbeat of 7.8125 ms.

Presumably some delay is necessary to assure that the controller firmware can turn the line around after transmission completes, but 1/2 millisecond just seems excessive to me.

I'm wondering if anybody in this forum has experience running AX-12's with a smaller delay time setting. Is there a reason why the default delay time is set so ridiculously high?

[JonHylands]

I think the default delay time is set so high so that people using really slow controllers like a Basic Stamp can handle switching from Tx to Rx.

- Jon

[limor]

I think the default delay time is set so high so that people using really slow controllers like a Basic Stamp can handle switching from Tx to Rx.

- Jon

Basic Stamp can't handle 1mbps. but ofcourse the dynamixel servos can be set to a lower baud rate.

There have been documented evidence of 70hz control cycle on 18 servo robots. here in the forum.
Actually i'm planning to try exactly these tricks the next few days and will report my finding and code.