I was looking in more detail at the MIT Cheetah and found this page - https://www.robotdigg.com/product/1667/MIT-Robot-Dog-high-torque-Joint-Motor -or-DD-Motor
It says that each motor takes an 8 byte payload to drive a motor, and that motor then replies with a 6 byte packet. After you add the CAN headers and trailers that is a total of 200 bits, best case, or about 416 updates per second for 12 motors on 1MHz bus. I was expecting the update rate to be a lot lower than that (I should have done the math). -----Original Message----- From: N [mailto:nicklas.karlsso...@gmail.com] Sent: Saturday, 22 August 2020 5:34 AM To: Enhanced Machine Controller (EMC) Subject: Re: [Emc-users] OT: Synchronised motion using RS485/CAN bus motors > ... > On CAN you can take advantage of the fact that all devices read the bus at > the same time. Each reader decides what information it wants to read and > ignore the rest so a time-sync heartbeat could be implemented if the nodes > all needed to be time synchonized. ... Yes all devices need to read bus within the time it take to send one bit because of the arbitration used to send the message with highest priority first. With CAN-FD speed is increased after address is sent so that message could be larger. _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users