USB Serial Adapters for CNC/DNC Applications

CNC-based manufacturing facilities require significant investments in capital equipment. Some of the largest of these investments are for the manufacturing machines themselves--everything from laser cutters, to drill presses, to painting robots. DNC application software packages are typically used to program and control these large, sophisticated manufacturing machines. However, advances in DNC applications have outpaced CNC hardware advances to such an extent that the PCs required to run them have significantly shorter life-cycles than do the CNC machines themselves. The result is that the serial-based CNC machines are often isolated when systems are upgraded to PCs that do not have native serial ports.

Quatech has worked with a number of CNC/DNC companies to help solve this problem. One popular solution is to use USB serial adapters (available from Quatech in 1, 2, 4, 8 and 16 port versions) to provide the additional ports.

Quatech USB serial adapters are industry leaders for speed--providing up to 460.8 kbps data rates that are ideal for most applications. For some CNC/DNC applications this can cause a problem, because it might inhibit the ability to process a "stop" command instantaneously.

One of our customers approached us with this very problem, and our Engineers went to work to create a specialized driver modification to accommodate the very specific CNC/DNC need. The driver modification consists of a new setting that enables the user to optionally limit the number of bytes loaded into the UART transmitter at a time.  This allows the box to stop sending characters more quickly if an XOFF flow control character is received. While this setting does degrade data rates, it is ideal for the CNC/DNC world where slamming on the brakes quickly is more important than moving data quickly.