USB and ncPOD system

> > IMO - The Ncpod has some limitations which should be made clear to any
> > prospective users.
> >
> > Each port is only rated at 20mA.
> >
> > Only one axis can be jogged at a time (multiple axis moves are fine
> > under code). In truth - this hasn't caused me any problem.
>
> And with a windows keyboard you can only select one at time anyway ;)

No. Hold down the up arrow and left arrow and Mach3 will move in two directions at the same time.
It will move in all three if you include the page keys.

>
> > PWM output is 75kHz, it's output voltage is only 3.5V and it will not
> > work with much of the existing hardware out there without modification
> > or additional hardware.
> >
> > Index pulse input doesn't work with Mach due to latency problems and is
> > not supported currently. Whether it ever will be would be guessing.
>
> Probably a separate discussion. Need code within the ncPod to handle this,
> because windows is not a real time OS. The parallel port only manages it
> because art has moved the essential code to the driver that sits in front of
> windows? I seem to remember the same problem with latency affection other
> modules as well.

I thought this whole idea of going to seperate real time boards was to take away the fact the box doesn't need to be in real time.
The underlying problem is that the board is only supplied 5v and most spped controllers require 0 -10 volts, some VFD's are now on 0-15v.
Perhaps the answer is a sererate supply from the speed control much like Arturo Duncans C11 / C11G boards ?

>
> > It will ONLY work reliably with USB 2.0 ports - even having legacy USB
> > support turned on in the PC bios will often cause "The pod has ceased to
> > respond". This particular problem has caused more support queries than
> > any other despite the information being posted numerous times.
>
> Much the same sorts of niggles as the parallel port? Not really the hardware's
> fault, but rather the crap underlying design of the platform and OS ;) What
> are the limitations of a good USB2 port, and what do we need to get around them?
>
> > There are also still a few other issues with the Mach ncpod plugin, Art
> > is aware of these and they will be fixed in due course.
>
> Nice to see this summary, it would be nice to have a little more data on the
> ncPod and perhaps it's own list rather than discussions around several. But
> since there are several uses for it it comes under several umbrellas and this
> group is not limited to a single product or area of computerised machining.

It does have quite a dedicated list going for it on the Mach3 web forum and the yahoo group and has been worked on for a while.

John S.