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Parallel port versus USB port

Here we are, after we have read everything and more on the internet   concerning cutters and cnc programs, here is the dilemma: can I communicate between the computer and the cutter control electronics with the old parallel port system (LPT), or through the modern USB port?

Good question isn't it?

So let's go in order and logic to see how we can get out of this situation.

lpt_vs_usb.png

Parallel port (LPT)

The parallel port was born on the computer mainly to be able to connect a printer or other mechanical / electronic system, see also scanner or FAX.

It is a communication system is dated, quite spartan, not very fast, the connector itself is   great,   with this port it was possible (and still can) to manage input and output signals very easily with simple programs even in DOS.

Thanks to the easy management of the LPT port, the first cutter control programs were created such as DeskNC, Kcam4, Ninos, but even today, two of the best programs for cutter control such as Mach3 and Emc2 work very well on this door.

If you decide to make or buy an electronics based on the parallel port, you will have several advantages and some limitations (I don't want to define them as disadvantages), let's see which ones:

lpt.jpg

Benefits

  • Low cost of electronics

  • Great ease of finding ready-made electronic diagrams or cards

  • Possibility of being able to use / test different types of programs and on different operating systems, see Mach3 and Kcam4 on Windows or LinuxCNC on Ubuntu.

  • There is no need for additional cards specific to the program used.  If necessary, you pay only the license of the program (Mach3 needs the license instead LinuxCNC is free)

Limitations

  • Logically the computer must have a parallel port, however, if it does not have one, you can add one on the PCI slot (costs about 18 euros)

  • It is preferable that the computer is a desktop since the LPT port is better managed (you can still find used PCs for less than 100 euros)

  • It is likely that on 64-bit systems or on W8 there are operating problems (however WXP or Ubuntu are very stable and performing systems. 

USB port

The USB port, on the other hand, is a more "modern" solution, all PCs, desktops or laptops, have one or more of these ports, even the data transfer speed is higher, it has now become one  standard for mobile phones, tablets, cameras as well as all computer peripherals.

usb.jpg

Benefits

  • It is present in all PCs, it is possible to use a laptop to operate a CNC cutter.

  • You have higher frequencies for communication

  • Much of the data processing is done by the specific card of the USB device and not by the CPU of the computer.

Limitations

  • The cost of electronics is higher due to the price of a specific add-on card

  • Usually,  if you want to use a cutter control program  for USB port (see USBCNC, Colibrì or CNCUSB), you will have to purchase a specific card provided by the program maker, so you will not be able to use / test different programs. It is true that for the Mach3 program several cards have been created that allow you to interface the program with a USB output, many of these are of Chinese origin. Honestly, however, with the cost of an adapter card you can easily take a used PC and dedicate it only to the cutter control.

My final advice is this: if you are a beginner and want to approach the world of CNC milling, opt for a parallel port communication with a Mach3 or LinuxCNC program, you will have excellent performance and I assure you that they are both  performing programs and at the same time simple, you will have time later to switch to a USB system…. if you feel the need.

(I advise you to read possibly also  this  my page if you are interested in more information)

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