Re: [CAD_CAM_EDM_DRO] Rutex R2000 new product! Comments please.

Lance Hopper wrote:

>Hello,
> Been out of the loop for a while. I noticed Rutex has a new
>product named R2000. It's got SPI, serial peripheral interface, what
>does this do? Also it 'appears' to have a pulse generator (up to 7
>axis!?) on board, ie. "...theoretical speed up to 80Mpps." A
>realtime 32bit DRO etc... Says to be available Jan 2005, which is
>well passed, but there is no mention of price.
>
> Does anybody well versed in electrical/CNC jargon care to comment
>on this products specs/features and it's possible significance to the
>hobby/low cost cnc market? It appears to have the potential to be a
>hot item, but I don't understand alot of it, and who knows how much
>it will cost.
>
>

Well - SPI is meant for communication between chips on a board. It uses
3 wires: data in, data out, and clock. You generally also need a chip
enable line, especially if you have multiple devices connected. A
number of microcontrollers also use SPI (or something similar) for
programming.

Using SPI to send rate commands, instead of using step pulses, makes a
lot of sense. Many chips can run the SPI Bus at 20 Mbits/second, so you
can get a lot of information back and forth. Since there's a
microcontroller on board, there is no reason to use an external timing
source - any microcontroller is 100 times better at generating accurate
timing than any PC today. (I have made devices with 1 MHz
microcontrollers that have 1 microsecond jitter on interrupt response,
something that's nearly impossible on a 3GHz PC)

The "7 axis" spec looks like if comes from the 7 sockets on their
carrier board. If they just send out 7 SPI commands at a time (in
parallel), it takes no longer to speed on 7 axes than it takes on one.
If they send commands in series, it can still take only 20-40
microseconds to send out the full set of velocity commands.

The 80Mpps spec has me a bit confused. I see a PIC microcontroller and
a 10MHz crystal on one board (it looks like 11MHz on some of the other
boards). A PIC divides the external clock by 4, so you get an internal
cycle rate of 2.5MHz. No peripheral on a PIC can run faster than the
external clock reference, so there's no part of that chip that can go 80
MHz, and there's no PIC faster than 48MHz. Some of the boards have
other chips I can't identify, so they may be capable of 80Mpps operation.

The "Built-In real Time DRO" is just a counter. With bi-directional
communication, it's possible to get position feedback from the drive.

I have no idea how much it will cost :)
- Steve