[Silencer]

Hi,

Does someone know where to find instructions for build hardware for Mach3 or maybe which controller to buy?
It must drive 3-axis CNC with 2.0A, 1.8° stepper motors.

Thanks

[jalessi]

http://www.geckodrive.com/product.aspx?c=3&i=14469

http://www.hobbycnc.com/products/hob...ver-board-kit/

http://www.joescnc.com/

http://www.cnczone.com/modules.php?n...category&cid=2

[Silencer]

Thank you jalessi, it was very usefull. Does someone have connection schematic for connection L297-8 hardware with parallel port which is driven with Mach3?
Is there need for some type of interface between, or I can drive L297-8 directly with Mach3 through paralell port?

Thanks.

[bharbour]

Does someone have connection schematic for connection L297-8 hardware with parallel port which is driven with Mach3?
Is there need for some type of interface between, or I can drive L297-8 directly with Mach3 through paralell port?

Thanks.

Mach 3 uses the data leads on the parallel port for step and direction controls for up to 4 axes.

pin 2 step X Axis
3 dir X Axis
4 step Y Axis
5 dir Y Axis
6 step Z Axis
7 dir Z Axis
8 step A Axis
9 dir A Axis

18 - 25 signal grounds

Limit/home switches and EStop switches use pins 10, 11, 12, 13, 15

You can change the assignments around inside Mach within reason.

You might be able to drive the step and direction signals on the L297 directly from the PC parallel port, but you run chances with grounding problems. I would probably use optoisolators to reduce problems with that. Many of the breakout boards have a safety device called a charge pump safety that requires Mach or whatever program is driving them to supply a stream of pulses on a different signal to enable the step and directioon signals. This prevents random wandering of your machine while the PC is booting and other such things. If you want to try driving the L297's directly, you will need a very clean and tight grounding design to keep things well behaved.

Good Luck,
BobH

[Silencer]

Thanks BobH,
I will use optoisolators for uncoupling whole CNC, and microcontroller for charge pump safety controll. I will also drive L297 with microcontroller (it will only forwarding data from parallel port) because I will have better controll of CNC.
Is it there something else what would be usefull to build in controller for make it better?



Thanks again.

[bharbour]

Thanks BobH,
I will use optoisolators for uncoupling whole CNC, and microcontroller for charge pump safety controll. I will also drive L297 with microcontroller (it will only forwarding data from parallel port) because I will have better controll of CNC.
Is it there something else what would be usefull to build in controller for make it better?

Thanks again.

It sounds like you have most of the bits for a breakout board. You might think about a spindle speed control voltage output or data stream if your machine will use a rotary spindle.

I am curious why you would have a microcontroller forwarding data from the parallel port to the L297's? Since time is also one of the aspects of the data, it seems like optos and maybe some nice fat '244 buffers to drive the optos from the parallel port would be all that is necesary.

Good Luck,
Bob

[Silencer]

Well you are right,but which 244 to use, HC (CMOS input levels) or HCT (TTL input levels), which one is better for parallel port, old parallel ports have 5V logic, new one I think 3,3V?

Regards

[bharbour]

I would probably use 74ACT244's. Running on 5V, it looks like the input thresholds would work with a 3.3V parallel port, especially if it was a CMOS output port. AC's probably would not. The Fairchild data sheets I looked at showed 24mA of output drive for the ACT's, while the HCT's only showed 6mA which is a little low for driving opto's. I usually use about 10mA for an opto drive.

[Silencer]

Yes ACT is better choice and I will use it.
Regards.