Re: deskcnc servo driver

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Gregory Kamysz
<smsupply@a...> wrote:

> With servo controls how does the software know the machine has

reached

> it commanded position if it starts to lag behind?

There is software embedded in the servo driver that reacts to the
commanded and known position. With DeskCNC there is simultaneous
trajectory planning that also provides smooth contouring across
multiple blocks of G-code movement.

>I understand that the
> servo control knows that the motor is behind but if the pc sends

the

> next command and it hasn't reached it's destination from the

previous

> command what happens?

What would you expect to happen?

1) The machine follows the commanded path in the order of the G-code
program as any other useful CNC controller.

unless

2) Conditions prevent this from happening, such as ramming the cutter
into a vise or the end of travel, and then the driver(s) will fault.

> I guess Geckos will only allow 125 step lag before faulting. Is

this

> really a problem?

How far is 125 steps on your system. If it is more than an
acceptable error, it's too much. If it is unreasonably tight then
you will have to artifically adjust acceleration to accomodate the
small step lag.

It may or may not be a problem, depending on the machine, screw
pitch, encoder resolution, and desired speeds.

Fred Smith - IMService