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View Full Version : Which Driver & What's the Difference



Mr.Chips
10-25-2003, 01:09 AM
Well I'v finalized the construction plans and now turned to the electronics.

Know nothing about drivers, and don't want to make too big of a mistake.

I'v heard a lot of talk about Geckodrive and looks like they would be about $375 for three.

This link (EAS) is selling bare boards for $10, and to fully populate three boards will run about $200, thats quite a savings if they are about equal. That I cannot tell the difference.
http://www.embeddedtronics.com/

I will be using Bipolar motors.

If one of the CNC Zone technical people could compare the Geco and the EAS drivers I would appreciate it. Or if you could suggest an alternative to thest two.

Thanks
Hager

ger21
10-25-2003, 07:43 AM
It really depend on the motors you're going to use. Gecko's can supply up to 7A @ up to 80V, while the EAS can only supply up to 3A @ up to 55V. You want to supply as high a voltage as possible for best performance, up to about 20x the motors rated voltage. This will give you the most torque at the highest speeds.
An alternative driver, that is used by a lot of people here, is the Xylotex board.

http://www.xylotex.com

While only 2.5A and up to around 30V (It's rated at 35, but recommended to be run @ 24V to 30V,) It's the best deal around for only $125 fully assembled. For another $60, he'll give you 3 motors to get you up and running for $200. For a small first machine, this may be all you need. Get the Gecko's for you're second, bigger, faster machine.

Gerry

Mr.Chips
10-25-2003, 09:17 AM
Gerry, thanks for the quick response.
More questions.

1. I see the Xylotex offers a one drive board. Could I use three boards instead of the three in one board? If one axis dies I could replace the one drive board, where on the three in one board I would have to replace the entire three in one board if one died.
Or are there better reasons to have the three in one?

2. Is the amps and voltage the only functional difference between the EAS and Xylotex boards?

3. The EAS lists an "Adjustable chopper current drive" and the Xylotex doesnt. What is this?

4. The EAS lists 10 microstep and the Xylotex lists 8. Is there much difference here.

5. I was looking at the Xylotex spec sheet of the motors and it seems to me they are unipolar, which can be ran on the bipolar driver as the Xylotex is. Would this not work as well?

6. In the EAS boards the PIC 16F84 must be flash programmed. And the Xylotex, doesn't mention this. Is that program already in the Xylotex board or is it handeled by the software?

7. I'm guessing both boards would work on the same softwares, is this true?

8. If I used the EAS board I would need a breakout board, also listed on the above link. Would I need one on the Xylotex board?

Sorry for so many questions.
Hager

abasir
10-25-2003, 10:19 AM
Hager,

I don't use both drivers but here are some answers to your questions.

Q1: Specification looks the same, just a matter of preference. I prefer the separate boards for the same reason you have.

Q3: They both have it. It's used to limit the current to your motors.

Q4: Theoretically, 10 microsteps give you better resolution compared to 8 microstep.

Q6: PIC16F84 is a microcontroller. It is a chip that can be programmed to do what you want. In this case, it's converting step/dir signal to signals required to drive the LMD18245. Xylotex may do it differently, possibly with other chips.

Q7: Both drivers works on step/dir signals. As long as your software support Step/Dir signals (and most do), you're okay.

Q8: Breakout board simplify wirings. Again, it's a matter of personal preference.

I didn't check the detailed spec of both drivers, that's why no Q2 & Q5 above ;)

Regards,

Mr.Chips
10-25-2003, 05:55 PM
Xylotex lists a single drive module XS-3525/8S-1. Has anyone used three of these instead of their three drive module XS-3525/8S-3?

I would rather have three single modules.

ger21
10-25-2003, 09:33 PM
The 3 axis is a lot easier to hook up than 3 single axis drivers would be. All you have to do is plug in the included parallel cable, a power cable to a spare hard drive power connector, connect your motor power supply and you're motors. If you're worried about a single axis failing, they can repair it for you for less than the cost of the single axis board. (I'm pretty sure it's around $30 or so, from what I've heard). If you email Jeff at Xylotex
( xylotex@hotmail.com ) , you'll find he'll answer any questions you have very quickly. Great service and support. As for you're other questions,
2. Not sure
3.The Xylotex current is adjustable up to 2.5A
4. Not sure if you'd notice the difference, but like abasir said, 10 should be a little better
5. 8 wire motors can be wired 3 different ways. Bipolar series, Bipolar parallel, and unipolar. Unipolar will give you less torque. Parallel will give you the best top end speeds, but uses twice the current compared to Series. You should read the Stepper motor white paper at http://www.geckodrive.com/support.htbml?order_id= . Lots of useful information there.
6. The Xylotex doesn't use a programmable chip. It's ready to run as is.
7. As long as you can set which pins are step and direction in the software, any board should work fine.
8. The Xylotex comes with a parallel cable that is all you need to get running. If you want to add limit switches, you'll need to make up some molex connectors to plug into the board. Example diagrams on their website. If you're software supports more than one parallel port, you can use the breakout board on a second port for wiring switches and/or relays and leave the Xylotex as is. As for the EAS board, a breakout board would make things easier, but you can always make a parallel cable to hook up directly to the board. Hope this helps.

Gerry

Marc Soren
10-26-2003, 12:52 AM
Isn't DenverCNC putting out a Xylotex based 4 axis controller, rated at about 2.5 amps and 24 volts? It is listed on the DenverCNC web site and also on Tim's K.T. Marketing but neither one goes into much detail on the individual drivers used in each axis.

I brought it up to show the potential of using one of the Xylotex type drivers. It is a complete 4 axis system with some of the usual bells and whistles, including two additional 110 V AC plug ins on the back that are controlled as well...and extra pin outs for limit switches, and so forth....again, just to show that the Xylotex format is cabable of going beyond bare bones that sometimes some home builders end up building at first.

I can't remember if it was discussed on the Xylotex discussion board somewhere on the net.

Marc and boyz

ger21
10-26-2003, 12:06 PM
Yeah, The Denver CNC is a xylotex, but I don't think it says that anywhere. I believe it was just talked about on the CCED list.

http://www.denvercnc.com/controller.htm

Easy way to get up and running if it's in you're budget.

Gerry

Marc Soren
10-26-2003, 09:54 PM
I wan't nec. advocating just plugging in a box, but pointing out that all 4 axis, the Power supply and isolation circuits are all together in a small package. It would still be nice to know which single axis card is being used. Rather like using the example as a goal of sorts.

I will see if I can find out, if it would help.

Marc

Mariss Freimanis
10-26-2003, 10:40 PM
Ask yourself this: If one drive blows up, am I better off with individual drives or a system that incorpoprates 3 drives in a single unit?

Mariss

Uwe-Wulf
10-31-2003, 05:10 PM
Hi.
You could find 3A/55V LMD18245 microstep applications with higher resolutions than EAS here:

http://cnczone.com/showthread.php?threadid=1209&highlight=odin3d

http://www.national-motion-control.de

Yours, Uwe Wulf