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March 2015, announcing the new PyMini software release. PyMini replaces the old existing rt-stepper software. This new release is python based and replaces TkMini which was written in TCL/TK. PyMini takes advantage of newer software components and provides an upgrade path with new OSs. This release provides the following new features.

  • Full Python 2.7 and Python 3.4 support for PyMini and plugin scripts.
  • Faster gcode execution with multiple step buffer support.
  • No pauses between gcode commands in Auto mode.
  • GUI is written in pure python using the standard python distribution, no other dependencies.
  • GUI has the same look and feel in Linux, Mac and Windows.
  • General digital output support (spindle, coolant, etc) using a separate Arduino Uno board.
  • Libusb 1.0 support.

Eckler Software offers a unique USB solution for CNC controllers with the rt-stepper USB-to-Parallel dongle. Users can use the rt-stepper dongle to convert a parallel port CNC controller into a USB CNC controller. Designers can integrate the rt-stepper dongle hardware into there own CNC controller.

Most CNC controllers are designed to be driven with a PC parallel port. Unfortunately parallel ports are thing of the past and many new PCs have no parallel port. Commercial USB-to-Parallel dongles do exist, but these dongles are designed for printers not CNC controllers. CNC controllers require XYZ step/direction signals. With the rt-stepper dongle you can now drive XYZ step/direction signals over the USB bus.

Driving a CNC controller with a PC parallel port requires a real time OS otherwise the stepper motors can loose synchronization. With the rt-stepper dongle this restriction is removed. The rt-stepper dongle provides the real time stepper motor control which means you can now use your favorite OS such as Linux, Mac or Windows. Each dongle provides a step resolution of 46,875 Hz.

Most commercial gcode interpreters do NOT support laptops with parallel port chipsets. This is not a problem with the rt-stepper dongle. You can use any Linux, Mac or Windows laptop or netbook with USB support. Laptops can provide dedicated CNC setups with minimal investment and work space.

PyMini is a powerful minimalist user interface written in python. A user can write their own gcode program using their favorite text editor or run a CAM generated gcode program on PyMini. You can verify the gcode program with or without the dongle connected and view the xyz paths executed on the backplot panel.

There is only one process that runs on the PC - PyMini. PyMini is a GUI front-end program that communicates to the dongle. Both manual and auto CNC operations are supported. PyMini main screen is showed below, for information see the PyMini documentation.

The PyMini software supports the same gcode interpreter and trajectory planner as EMC/LinuxCNC. See the "Gcode Overview" section at for gcode syntax. Note, mcodes are handled differently in PyMini. Most mcodes are implemented via python plugin scripts. This means spindle, coolant and homing can be executed via custom python scripts.

I started using EMC back in 2002. I developed this product after using EMC for several years with my Sherline CNC mills. EMC worked great, but requires a PC with a real-time kernel and a parallel port to control the mill. Now I have the best of both worlds EMC/LinuxCNC based software with no real-time kernel requirements.

I have two mills and two CNC controllers - Camtronics and Xylotex. I now use the PyMini software exclusively. I can use the latest notebooks, which have no parallel port, with my old CNC controllers.

Originally I built the dongle PCB on my mill. Now the dongle PCB is made at a local USA circut board manufacturer, but I still make the custom case with PyMini. You don't get a feel for a product unless you use it.

I used Eagle CAD to develop and build the PCB. The engraving software I used for the case is called engrave-11-inline. Engrave-11-inline is a good example of using a real programming language, in this case python, to develop gcode output.

Buy one rt-stepper dongle without case $59 + 5.35 shipping (US address only).

Buy one rt-stepper dongle without case $59 + 16.95 shipping (non-US address only).

Buy one rt-stepper dongle $79 + 5.35 shipping (US address only).

Buy one rt-stepper dongle $79 + 16.95 shipping (non-US address only).

Save on shipping with multiple orders to the same address. Actual shipping will be adjusted to a single shipping charge (at shipping time).

The rt-stepper dongle hardware is based on the Microchip PIC182455 processor. If you are board designer and would like to integrate the dongle hardware into your own application. I am willing to sell you preprogrammed pic chips for your application. Based on my sublicense agreement with Microchip this arrangement works best because each pic chip must be programmed with unique USB descriptors (ie: pid/vid, serial number, product ID).

Be sure to use the rt-stepper dongle as your reference design with your application. Because any hardware or software support would be based on the dongle only. Please email me for more information.

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Last updated July 18, 2015