Re: [CAD_CAM_EDM_DRO] Re: servo vs stepper

It sounds counter-intuitive, but a serial port is capable of
transferring enough data.

at 115.2kBaud, that's 115.2 bits/ms or 11 bytes per ms. If you do 500
updates /sec, you get 22 bytes.

With a suitable protocol (sending acceleration commands instead of
velocity, for instance), you can pack a fair bit of information into 11
bytes. (3 axes at 3 bytes each = 9 bytes, so you could even send direct
velocity values 100 times per second)

- Steve

Jon Elson wrote:

>SERIAL PORT? I'm getting ever more concerned that this is the problem!
>I really don't know enough about this Galil card, and you had it checked by
>the manufacturer, but that seems like a real bottleneck. I assume the
>computer sends a velocity to the board, and the board generates the
>step pulses and keeps count. But, the serial port can only update the
>velocity so many times a second. (I do it 1000 times a second on my
>universal stepper controller) so the velocity is ramped up and down
>very smoothly. I seriously doubt they can do it as smoothly with the
>commands
>going through the serial port.
>
>Jon
>