Originally Posted by
Megahertz
Another issue might be the windows "multitasking/multi thread environment". I would think the CNC program would send one byte of info. to port 378hex and right away sends one byte of info. to 278hex. You only delay is a few processor clock cycles (a very very small delay). But, What if the CNC program sends info. to port 378hex and then the Windows enviroment stop the "CNC program" thread to take care of one of the many other processes that would be operating. The OS will eventually return to the "CNC program" a send info to port 278hex. However, many processer clock cycles have now occured between the port378 write and the port278 write. Perhaps the CNC software can be written to prevent this break in thread execution from ever happening or you can reduce the quantity of background programs or services (virus scanners, screen savers) sucking up processor resources. My programming knowledge doesn't extend this deep into the OS.