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Author Topic: To Grex or not to Grex?  (Read 6224 times)

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To Grex or not to Grex?
« on: April 17, 2006, 02:29:40 PM »
So, I am finally building my router table. 4'*8'*16"Z. Have gathered most of the mechanical parts and most of the electronics. Planning on using some compumotor drives and using some 2500 ppr encoders for feedback. The Grex looks to be ideal for this, but is the software ready enough to take the plunge? I really dont want to buy hardware twice.

What do you guys think? Go parallel or grex it?

-Jerry
Re: To Grex or not to Grex?
« Reply #1 on: April 17, 2006, 07:07:42 PM »
2,500 PPR encoder, maybe a 3,000 RPM motor equals 500,000 step pulses per second. That's 10 to 20 times higher than the Mach2/Mach3 maximum step rate but only 12% of what Mach4 can do.

Mariss
Re: To Grex or not to Grex?
« Reply #2 on: April 17, 2006, 07:24:47 PM »
Guess that pretty much tels me whereI want to go, though I am using steppers so I doubt I wil get that fast...

Whats the difference between the g101 and g100.  case/terminals/psu + the rabbit board? Is the g101 as simple as slapping the rabbit board on it and loading the firmware or do need to flash the rabbit board too?

Sorry id this is repeated elsewhere, but I searched in vain on the gecko site for a detailed description of the units and their differences and was only able to garner a morsel of informtion on the web.

-Jerry
Re: To Grex or not to Grex?
« Reply #3 on: April 17, 2006, 08:10:18 PM »
Sorry about that; I guess it could be clearer.

1) The G100 and G101 are functionally identical. That means the same program run on either one will give exactly the same results.

1a) The G101 is an OEM version. It has no indicator LEDs, no terminal blocks for connections (headers only) and no enclosure or case. It really requires a user to design a printed circuit board the G101 can plug into.

1b) The G100 is an end-user version. It is also more expensive because the "gingerbread" listed in (1a) costs money.

2) The G100/G101 is an 8-bit perephrial (8-bit data bus, RD, WR, CE, 4-bit address bus, etc). It requires an 8-bit microcomputer to operate it. The interface connector is pinned-out for a Rabbit RCM3600 or RCM3700 series MCU though any other CPU can be used.

The Rabbit must be flashed with the firmware here (Geckodrive) unless you have a Rabbit development system and the required programming cable. We flash the Rabbit and sell it at cost with the G100/G101.

Mariss
Re: To Grex or not to Grex?
« Reply #4 on: April 17, 2006, 11:29:30 PM »
It is going to be a bit before the Grex is fully tested... If you need to run the machine today and make parts please look into getting set up with the printerport and then you can move over to the Grex after.
thanks
Brian
Fixing problems one post at a time ;)

www.newfangledsolutions.com
www.machsupport.com
Re: To Grex or not to Grex?
« Reply #5 on: April 18, 2006, 12:12:41 AM »
Makes no differece to me and I agree with you. The G-Rex is the future; in 5 years PCs won't have parallel ports. None of my computers have them, they are becoming as rare as ISA bus boards are now. It's just the direction in which things are going.

About the leading edge of technology. avoid it like the plague. It's not called the "bleeding edge of technology" for nothing. Let others shake it down until it is safe and stable. Meanwhile others have to see where things are going and have to have products in place:-)

Mariss
Re: To Grex or not to Grex?
« Reply #6 on: April 18, 2006, 12:32:48 PM »
In all reality I will not be ready to start wiring for more than a month. Hopefully this weekend I will pick up the base that I am using and then figure things out from there. Sounds like I will probably go with the GRex Figure two months to figure out exactly how I want.

Do you guys think it would be better to tie the encoders to the motors screws directly or hook to the axis? I would like to use the closed loop system in the GRex to eliminate as much backlash as possible.

-Jerry
Re: To Grex or not to Grex?
« Reply #7 on: April 18, 2006, 06:55:32 PM »
There is no backlash comp in the Grex now :( It also is not a closed loop at this point...
Fixing problems one post at a time ;)

www.newfangledsolutions.com
www.machsupport.com
Re: To Grex or not to Grex?
« Reply #8 on: April 18, 2006, 07:08:14 PM »
True but the G100 firmware can be updated via the ethernet link. That means as features are added (backlash, closed-loop, etc), you can download the updates and flash them to the G100 using the installed DLM. It cannot become obsolete.

Mariss