Most of us are familiar with USB flash memory devices (also called flash drives or data sticks) for storing documents and digital photos. They are a convenient way to move files from a laptop to a desktop PC, from a camera to a PC and so on. They can also be handy for storing and moving part programs for CNC machines on the shop floor.
Calmotion LLC (Chatsworth, California) has developed a reader/control unit that acts as an interface between commercially available USB flash drives and CNC units with RS-232 serial ports that can be used for data input. Called the USBCNC, the system allows machine tool files to be sent from the flash drive to the CNC and from the CNC memory to the flash drive. Data from the flash drive can also be “drip fed” into the CNC. “Drip feeding” lets the CNC read in each line of the part program code as needed to execute the machining operation. According to the company, DNC (“direct” or “downloading” numerical control) firmware is built into the reader/control unit so that it can be connected to almost any machine tool CNC unit.
The USB reader/control unit helps shops with CNCs that have limited memory capacity. Proprietary memory upgrades for these CNCs may be prohibitively expensive or unavailable. The reader/control unit is an alternative. Libraries of part programs can be stored on a single flash drive (a 1 GB drive comes with the system). Likewise, the system is an alternative to either using a PC on the shop floor for DNC or stringing long cables so that the PC can be placed in a safer location.
In operation, the reader/control unit displays simple messages or a directory of files stored on the flash drive. Three buttons on the reader allow the user to scroll up and down and select items. The unit can be mounted on a machine tool CNC panel or enclosed in an aluminum housing to be used as a hand-held pendant.
A similar USB reader/control unit specifically designed for Fadal CNC units is also available. This version, the USBCNC-FAD, uses the display panel on the Fadal CNC for operation and has other features tailored for integration with this make of control.