Parallel Port or dedicated motion control

[mccafferty]

I am building a CNC router with stepper drives. I am leaning toward Mach3 for the control software. My question relates to interfacing the PC to the machine.

I would like to better understand the pros and cons of connecting using parallel ports or a dedicated motion controller. I will commit a PC to the machine and don't care if it is a desktop instead of a laptop. I am mainly interested in performance related comparisons. I did some searching and found dated information on ncPOD, but didn't see anything current.

Some information that would shorten my research as to best approach and current product offerings would be much appreciated.

[ger21]

The most popular current offering would be the SmoothStepper. www.warp9td.com
I've never used one, but here's what I've read.

SmoothStepper offers these features vs parallel port.

Faster pulses, up to 4Mhz, vs a max of 100khz on the parallel port, if your lucky.
Smoother pulse train, which may give slightly more speed, and smoother running motors.
USB, so you don't need a parallel port.
Gives you the equivalent of two parallel ports.

If you have a PC that outputs a good, fast pulse stream through the parallel port, then maybe the SmoothStepper doesn't offer much.

Keep in mind that the Smoothstepper is really still a beta product. Some features do not work correctly, or not the same way they do with the parallel port. It might be a good idea to join their support forum and see how it's progressing. There are a lot of users using it, though, and it shows great promise.

[keebler303]

I have two smooth steppers. I bought one a while back and got my second one in the mail today. I haven't gotten one into a working machine yet but I have hooked it up to some gecko drives and steppers and it works as promised. It seems to be fairly complete as far as the base features. The work now seems to be on tweaking the advanced features and adding some "cool" features that you can't get with the parallel port.

Its almost plug and play, and it seems to work great. The only bad thing about it is that it has been so popular that they can't keep them in stock. Seems that the entire order of them is sold before they get them. I'm sure they will get caught up soon though.

Also the person I have dealt with (Stephanie) has been friendly and helpful.

I would definitely recommend a further look into a Smooth Stepper.

Matt

[Dorsal]

I'm running a 3-axis router (PhlatPrinter) on the Easy-CNC 3-axis control board, which has a parallel-port interface. Because of space limitations, I must run it from a laptop, a Dell Latitude D800. Therein lies the trouble - most laptop computers have ports that are good for printers but nothing else - the port voltage is only 3V (not 5V like a desktop) and the parallel port is interrupted for everything the laptop wants to do. It was very frustrating, and the best I could get was about 8IPM without so many interrupts and dropped pulses to trash everything - sometimes.
I bought a SmoothStepper and have hooked it up. The installation was painless, nearly plug-and-play, and my performance jumped to 50IPM (once I found and killed the electrical "noise"). The SmoothStepper does seem to make my system more sensitive to "noise", but a grounded metal enclosure and a diode/capacitor filter on the fan motors (to cool the heatsinks on my controller board) has done the trick, and without it I would definitely not be able to run at all.
There seems to be a 4-week waiting list to get one, still (that's how long I waited, also), but it was definitely worth the wait.

[ger21]

One thing to note is that inputs are a bit slower with the SmoothStepper, due to the USB connection.

[mccafferty]

I had found information on the web for something called a ncPOD, but the posts are a year or two old and I haven't found anything on it recent.

Something I hadn't noticed at first glance is that the SmoothStepper is a parallel port replacement meaning that you still use a optically isolated breakout board but just replace your parallel cables with this board and USB cable. Kind of a neat trick for migration if it doesn't cost you performance.

It seems the world is going to have to migrate away from parallel ports as they are getting less available on machines.

I have a 3.2GHZ desktop with 2 parallel ports that never gets used. Maybe the best approach is to do the parallel port approach with a breakout board knowing that I can migrate to USB when and if needed. I mainly hated to build the machine around something that I can't support.

Looking through web searches and forums, it looks like the CNC4PC C23 board is full featured and with isolation... Anybody know of a better approach?

Thanks for the input.

[ger21]

The nCPod plugin for Mach hasn't been worked on in over a year, and from what I've read, most of the early ncPod adapters put them on the shelf and switched to the Smoothstepper.

[salzburg]

I came across this USB-Parallel Interface on the net.
www.cncdudez.com .
Has anyone built it and used it and if so does it work with Mach3.

[keebler303]

Originally Posted by salzburg I came across this USB-Parallel Interface on the net. www.cncdudez.com . Has anyone built it and used it and if so does it work with Mach3.

It doesn't work with mach3 and it sounds from the comments on their site that it is not terribly well supported.

"...Not even time to answer emails..."

Matt