rt-stepper ERS
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September 2013, announcing rt-stepper software release 2.0 This release provides the following new features.

  • Python script support for mcodes.
  • General digital output support (spindle, coolant, etc).
  • Axis homing support.
The python interpreter comes built into the rtstepperemc library, no new dependencies. Now users can customize their mcodes via python scripts. Standard python scripts are installed with the software for spindle and coolant mcodes. Homing is also supported with python scripts. See the ERS for more information.

September 2012, made a significant speed improvement executing gcode. Command motor moves are now double buffered. The trajectory planner will create a step buffer for each gcode line. While one step buffer is being executed by the rt-stepper dongle the trajectory planner will create the next step buffer. This means back-to-back gcode lines will execute faster. Previous support only used one step buffer.

July 2012, added support for ACTIVE_HIGH step/direction logic in the .ini file. This will allow support for Gecko G540 CNC controller boards. Previous support was ACTIVE_LOW step/direction logic only.

April 2012, I now offer the rt-stepper dongle without the case. You can still buy the dongle with a case, both options use the same circuit board or PCB. The PCB comes fully assembled and tested. Instead of making the printed circuit board on my mill I ordered a batch of PCBs from DorkbotPDX. The PCB is a stellar quality 2-layer lead free purple board with soldermask and silkscreen on both sides. With the new 2-layer board I now support three IO inputs instead of one - INPUT0, INPUT1, INPUT2. All three inputs can be used to signal a estop.

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.

The rt-stepper software (rtstepperemc) is open source. Starting with version 1.7 the software is based on the EMC2 open source project at www.linuxcnc.org. This provides a number of improvements over the original rt-stepper software - 4-axis support, complete gcode interpreter, trajectory planner, GUI front-end and Backploting. Since the rt-stepper dongle provides the real time step pulse generator this version of EMC2 can run on Linux, Mac and Windows with less runtime dependencies.

There is one process that runs on the PC - TkMini. TkMini is a GUI front-end program that communicates to the dongle. Both manual and auto CNC operations are supported. TkMini main screen is showed below, for more screen shots see the rt-stepper External Reference Specification (ERS).

The rt-stepper software supports the same gcode interpreter as EMC2. See the "Gcode Overview" section at www.linuxcnc.org for program syntax, parameters, expressions, binary operators, functions and looping constructs. See the ERS for rt-stepper specific features and instructions.

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 EMC2 based software with no real-time kernel requirements.

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

I first introduced the rt-stepper dongle back in 2009 with my own small terminal program that ran a small subset of CNC gcodes. I have no plans for new development on the rt-stepper classic software, but rt-stepper classic software is still available on the download page.

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 rt-stepper. 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.

© 1996-2014 Eckler Software

Last updated November 23, 2014