[Jesse B]

Up until now, I was fine with using a Parallel-Port-Based breakout board; I still am really. However, recently I've run into a couple USB-Based models, and they've got me thinking. Obviously USB would be preferable over Parallel, for the obvious reasons. I'm wondering how viable this option is. I know that the CNC guru's seem to frown upon the use of USB, but I've never known why. That'd by great if somebody could teach me.

There are 2 major things that I'm worried about here; Hardware and Software.

1) Hardware:

I recently came across this website, and this board looks to be pretty nice. There is a professionally made version, as well as a DIY version. It uses the PMinMO standard connections, so it'd be compatible with the SLAm Stepper Drivers I was planning on using. You can also connect 8 limit switches, 8 jog buttons and 3 outputs to controller.

I'm sure there's alternatives out there, and I'd prefer either A) Inexpensive versions, or (preferably) B) DIY, open-source versions.

Is there any reason not to use something like this? Is the 25 KHz maximum step frequency adequate? Also, would it be easier just to use something like a USB-to-Parallel converter board and a standard Breakout Board, or would the dedicated USB unit be easier?

2) Software:

I haven't done a lot of research yet, but I understand that you need a USB G-Code interpreter in order to use a USB Board. CNCDudez offers just such software, as does EdingCNC and PlanetCNC, the maker of the above mentioned board.

What would be recommended to use? It can run on Windows or Linux, and I'd prefer for it to be free, but if the software is vastly superior, I am fine with a small charge. Please note that I am merely a hobbyist, and don't need the best that is out there; just something that would work.

So that about covers it I think. A recap of questions:

- Is this a viable options?
- What hardware is recommended?
- What software is recommended?

Thanks,


- Jesse

[beliefdrive]

i thinks you can coding plugin for mach3, like SmoothStepper
http://www.warp9td.com/
new computer or laptop don't have lpt port

[Jesse B]

i thinks you can coding plugin for mach3, like SmoothStepper
http://www.warp9td.com/
new computer or laptop don't have lpt port

Awesome, I'll definitely look into that further when I get some spare time

I've done a bit of reading, and I figure a Parallel Port can do about ~45kHz stepping frequency. The particular USB board I was looking at is only capable of ~25kHz. Realistically, over a span of under a foot, will I see any detrimental effects?

Thanks,


- Jesse

[Jesse B]

Alright well I finally sat down, did some reading, and a few calculations. I figure with 25kHz, that gives me a [maximum] of 187.5ipm with 1/2-10 screws and using 1/4 stepping. I figure for axes of 6", 4" and 4", that should be plenty fast, with lots of room to spare for different step-modes and lead screws.

So this is seemingly pretty intriguing so far. Nobody has any reasons why not to use this? No other suggestions either?

Thanks,


- Jesse

[ger21]

You can't use just any software with any USB option. Each option has their own dedicated software to support the USB device.

The Planet-CNC device only works with their software.
The EdingCNC device only works with their software.
The Smoothstepper only works with Mach3.


And Mach3 is capable of 100Khz through the parallel port, if you have the right PC.

[Jesse B]

You can't use just any software with any USB option. Each option has their own dedicated software to support the USB device.

The Planet-CNC device only works with their software.
The EdingCNC device only works with their software.
The Smoothstepper only works with Mach3.


And Mach3 is capable of 100Khz through the parallel port, if you have the right PC.

Thank you very much for the input. It'll be taken into consideration.

What kind of PC are we talking about here? I'm running a Dual-Core @ 2.67GHz w/ 3GB of DDR2 atm, although I have another PC with a Dual-Core @ 2.8GHz and 2GB of DDR3. I also have a PCI Parallel-Port Card. I assume either of these are adequate?

[PEU]

true most new motherboards do not include parallel port, some still have the connector in the board but they dont provide the cable+bracket
But you can purchase a PCI parallel port and have the same functionality, I do this for every machine I sell, one word of advice, not all pci boards work, the other day I purchased a dual parallel pci card with chipset sunix and it didn't work because these ports do not have an i/o range that mach3 can use, changed brand/chipset and problem solved

For using mach3 at 35Khz an AMD sempron w/1gb ram does the job, no need to go dualcore, but given the prices, dualcore is a few bucks more so it pays to have a better pc.

good luck!


Pablo

[Jesse B]

true most new motherboards do not include parallel port, some still have the connector in the board but they dont provide the cable+bracket
But you can purchase a PCI parallel port and have the same functionality, I do this for every machine I sell, one word of advice, not all pci boards work, the other day I purchased a dual parallel pci card with chipset sunix and it didn't work because these ports do not have an i/o range that mach3 can use, changed brand/chipset and problem solved

Thanks. I'll have to check what chipset my card is running on.

For using mach3 at 35Khz an AMD sempron w/1gb ram does the job, no need to go dualcore, but given the prices, dualcore is a few bucks more so it pays to have a better pc.

good luck!


Pablo

Heck, they're so cheap I just can't resist I have both these machines built anyways. The former is the one I'm using currently, and the latter has a faulty power supply which I've been attempting to fix (due to me being cheap ) to no avail. I built the [currently broken] rig partially for this purpose anyways

What is the reason for the USB boards only working with their specific software? Just as simple as the specific pinout on the MCU? Would it be possible to design a board and write a plug-in for any control software out there with some work?

Thanks,


- Jesse

[RomanLini]

Hi Jesse, my suggestion would be to just use a parallel port and an older dedicated PC. For good performance a dedicated PC is vital as you can strip down the operating system and you can get a old second hand PC for $100 or less.

It also frees up your good PC to do CAD so you can be working on a CAD design at the same time as your old machine is cutting the job. You also get the option of building the old PC into your control cabinet etc etc.

[Jesse B]

Hi Jesse, my suggestion would be to just use a parallel port and an older dedicated PC. For good performance a dedicated PC is vital as you can strip down the operating system and you can get a old second hand PC for $100 or less.

It also frees up your good PC to do CAD so you can be working on a CAD design at the same time as your old machine is cutting the job. You also get the option of building the old PC into your control cabinet etc etc.

Yeah, I'm starting to think everything would be easier if I went with this approach. I've got 3 PC's, so that isn't a problem

I just wanted to know if USB was a viable option, as I didn't really know much about it. I'll just go back to my original plan though

Thanks,


- Jesse

[Jesse B]

While we're here, I've got a quick question about a BOB. I plan on running 3 SLAm Drivers. Do I need something as elaborate as the DIY 4-Axis Board from PMinMO, or will the Basic DB25 BOB work?


- Jesse

[RomanLini]

You don't need anything elaborate.

James has a low cost breakout board kit which is compatible with the SLAmSteppers so you can order all together;
4-axis breakout board

[Jesse B]

Most excellent, thank you sir

[Jesse B]

Also, I'm just kind of fooling around making a schematic for my own BOB, built with the absolute bare minimums. Do I need pull-up resistors at all? I'm pretty new to designing electronics

Thanks,


- Jesse

[RomanLini]

In most cases you can just attach the parallel port outputs directly to the STEP and DIR pins as they are logic level.

Going back 15 years or so I used to attach a lot of experimental logic level stuff to the parallel port, it's a fairly high performance port if you are not restricted by windows. In those days it was PC software written in dos, which offers very high performance.

[Jesse B]

In most cases you can just attach the parallel port outputs directly to the STEP and DIR pins as they are logic level.

Going back 15 years or so I used to attach a lot of experimental logic level stuff to the parallel port, it's a fairly high performance port if you are not restricted by windows. In those days it was PC software written in dos, which offers very high performance.

Okay, thanks.


- Jesse

EDIT: The simplest BOB possible Only breaks out X, Y, Z, Limits, Home, and Probe pins.