21. I used a USB Bit Whacker with a little bit of custom software, plus a quad-stepper driver with chips from Allegro to drive my CNC Frosting Robot. (http://greta.dhs.org/FrostBot and http://greta.dhs.org/EasyDriverQuad) The total parts cost of this setup (USB to four axis microstepping drive) was probably on the order of $50.

*Brian

Posted at 2:48PM on Mar 4th 2008 by Brian Schmalz

22. Why serial/parallel/usb? Why not ethernet/wireless?

Posted at 3:19PM on Mar 4th 2008 by Eion

23. I got one of these to control a parabolic dish im using. it can only do .5a for steppers and you would have to wright software to have it take cnc commands easy. right now you send through HT "(WM1F100)" that moves stepper 1 forward 100 steps. i love it and am so happy to have it.

Posted at 4:48PM on Mar 4th 2008 by alex

24. http://robomicro.co.uk/

Posted at 5:04PM on Mar 4th 2008 by alex

25. I think rs232 is all we need. Use TTL level rs232 for communication between devices. If you need to communicate long distances, you can use rs485. Fortunately, rs485 is just a hardware layer on top of normal serial, so you could implement it as a dongle for easy use. To go to a computer, just use a usb -> rs232 convertor. That way the software will does not need to change on the device to implement either USB or long distance communication.

Posted at 5:10PM on Mar 4th 2008 by Sean Clark

26. How about cypress microsystems PSoC Encore III that has a USB UART code module built in to allow the usb port to enumerate as a com port. You can configure analog input or use all the pins as I/O. I set one up for analog input of a sensor and the board only has 4 components... a signal cap, 2 usb signal resistors and a bridge resistor for the sensor... The microcontroller can be coded in C or assembly if you prefer. I'm not an EE or a CS programmer. Using the web and the psocdeveloper forum was able to set up a device that works well. No external crystal required and the software is free and makes the pc driver for you when you compile. Talk about a slick setup.

Posted at 5:53PM on Mar 4th 2008 by rr

27. I prefer rs-232 for controlling embedded stuff. The drivers are simpler. This is good since my experience is that, given complicated protocols, many manufacturers will screw them up or (worse yet) roll their own.

I also like serial because I can use hyperterminal (or z-term or kermit) to talk to the device when I need to test something. No (invariably broken) special tools that won't install under my OS, no (usually insufficient and/or brain-damaged) APIs written in Visual Ada.NET.

I use a laptop that has no serial port, but the usb-to-serial adapters work really well. If you insist on USB, the USB Bit Wacker seems to have things basically right. It presents itself to the computer as a standard modem device which you then talk to with normal serial using normal serial tools. Works on my mac, works on my pc. Folks running Linux seem to be able to use it fine.

9600 8,N,1 please. No flow control. If you're doing something that 9600 baud won't keep up with then by all means, go faster. If not, please don't. If you're doing something that 115k won't keep up with, then there is a really good case to use USB along with all of its associated nasty issues.

Okay, I feel better now. Thanks for listening.

Posted at 7:23PM on Mar 4th 2008 by Benjamin

28. As suggested by others, the have-your-cake-and-eat-it-too solution would be a microcontroller with a serial interface ... then attach it to a USB-to-serial conveter (ie ft232). The serial version would plug directly into the micro, the USB version version would use the converter. Since the USB port would appear as a "virtual" serial port, you'd even be able to get by with one piece of software on your PC.

But, of course, this isn't really making the most of USB. What would full-on USB get you? More bandwidth, mostly. What would you do with more bandwidth? I don't know enough to answer that question...

Posted at 7:30PM on Mar 4th 2008 by Marburg

29. USB to rs232 adapters do work most of the time. USB to parallel port adapters never work for control projects. Take a look at the BitWhacker:

assembled:
http://www.sparkfun.com/commerce/product_info.php?products_id=762

kit:
http://www.sparkfun.com/commerce/product_info.php?products_id=8265

Better yet the source code is available for download in case you want to roll-your-own using the PIC 18F2550.

Posted at 7:33PM on Mar 4th 2008 by Jimbo

30. how about a usb to serial emulator found in vinyl cutting plotter? it basically makes a driver to use a usb port think its a serial port?

Posted at 7:54PM on Mar 4th 2008 by r1cebrner

31. Having used both the parallel port and the Gecko G-Rex G100 for custom coordinated motion control projects, I can comment on this a little. A typical scheme used for attempting coordinated motion (i.e. CNC) with a PC involves directing stepper drivers via a sequence of step and direction pulses from the parallel port. This works fine up to a certain feed rate. A problem arises when the speed rate increases. Since most operating systems are multi-threaded and not real time, they use time slicing to do multiple tasks like keep track of time, accept mouse and keyboard input, update the screen, look for viruses, etc. Yes, a lot of this can be eliminated / optimized etc. and yes DOS and Linux have been used to a greater degree of success, but the problems and limitation still exist to a degree. Another option is to use external dedicated hardware like a microcontroller or FPGA to generate the driving pulses. These can operate in real time since they don't have the overhead of an OS to worry about. The UI on the PC then is only responsible for sending a description of the motion required (the G code for example) to the actual pulse generation hardware. This is easily achieved via USB or a virtual com port (over USB) for all the serial fanatics. ;) This is the regime that the G100 uses. Incidentally, the g100 comes loaded with a proprietary motion control language. While it differs from G-code, it's not too bad to use. It does suffer from one fatal flaw though, in that it has no command to stop motion once it has been started. Mariss Freimanis, the designer of the device, (and a very talented EE by the way) has promised to include the feature in a future firmware revision. You can, of course, stop the motion via power interruption, albeit a bit brutal.

Posted at 8:39PM on Mar 4th 2008 by keystoneclimber

32. What about control through ethernet port?

Posted at 10:38PM on Mar 4th 2008 by Mechpin

33. -Make explosives explosives control everything...

but yeah seriously i do not do enough hacking or DIY stuff to ever have run into this so just go with previously stated idea.

Posted at 10:56PM on Mar 4th 2008 by A_Blind_man

34. For small servos rather than steppers check this little beast out:

http://www.robix.com/usbor%20overview.html

One Usbor controls up to 32 servos and has 32 Analog Inputs, 8 bit for user sensors.

Posted at 4:03AM on Mar 5th 2008 by John

35. The only problem with serial ports is that manufacturers are opting to not include them on new pc. Usb is good, but still requires a driver of some sort to match the usb-> serial adapter.

What I have tried , and it works , is using the sound card. Uses a variant of I2c to send clock pulses on the left out, and data on the right out. Input is done the same way on the line in jack.

It was just a proof of concept, but it works.
Kind of neat to be able to look at the data visually in a sound editor, then just essentially play back the wave file and the micro takes it as instructions on what to do.

Posted at 10:25AM on Mar 5th 2008 by mworks

36. Actually I've done a lot of work on this for a project I'm building (basically a rapid prototyper with a half-twist). For bandwidth, future-proofing and modular-goodness, I've gone to network hardware and a Java front end. You can network-enable any parallel hardware with a network printserver and a very small bit of coding. Phidgets are just too damned slow for this sort of thing. Tried it. Bleh. Make: controller worked great though (until I wanted it for another project)

Posted at 1:00PM on Mar 7th 2008 by Mike

37. I may be just an old-schooler, but couldn't you make a controller that goes from one of those USB to LPT to your CNC machine?

Posted at 12:23AM on Mar 9th 2008 by William

38. Help! I am looking for an interface/sensors/control system to monitor/control 20 points on a generator. This unit should be able to operate autonomously (over rev control, if this then that) and also be monitored (temp points, RPM, power, fuel level, etc.) and controlled via the web. This is a hobby project that I hope to commercialize so budget is limited. I would hope to use off the shelf parts and software to right simple control scripts. Any ideas or information would be much appreciated. Please email me direct at cw787@hotmail

Posted at 12:54PM on Mar 11th 2008 by Christian

39. I'm a fan of ethernet and http. No, it doesn't allow for real-time control and requires some fairly hefty processor power and OS at the other end of the wire, but if I can upload my program to the CNC machine from my web browser, then I can sell it to someone who uses any OS, any hardware, and any browser. I don't have to support drivers and Winblows dll's. I don't have to support Steve Jobs (though I do so, willingly :). That is, I only have to support the hardware I sell, so the tail/warranty cost is minimized.

Rabbit has some nice modules. Lantronix makes some modules, too. Not cheap, but I think the up front investment is worth it.

Posted at 9:45AM on Mar 16th 2008 by Bill Eccles

40. Mouser sells a nice USB -> TTL cable for $20, (TTL-232r is the manufacture part #, FTDI). Data rates from 300 bps to 3 Mbps. The onboard chip is reprogrammable so you can change what signals are on what wire, invert signals, assign your own serial # ect. There are drivers for both UNIX and Windows.

The company also makes several other breads...USB -> JTAG/SPI/I2C

Posted at 10:17PM on Apr 1st 2008 by govtcontact