Keyspan USB to Serial Adaptor information:
Model Number USA-19HS
Before this adaptor I tried Radio Shack one. It was not reliable at all. It worked fine for short periods then would get lost.
This adaptor has been used on Windows 2000 and Window XP Pro. The drivers and setup assistant software allow some configuration changes and testing. Nice feature but I have not had to use it. The Keyspan adaptor has been rock solid. It has been used to interface with PDA and GPS equipment. I think one of the problems is some the adaptors do not handle serial interrupts correctly. Keyspan seems to have it right.
The Flashcut system (Version 2.0.9) is a stepper type. Controller chip is V0T9N-0404. I believe this chip has max baud rate of 57.6. Keyspan Adaptor is capable of higher rates.
I do a lot of X-Y contour cutting. The nature of the contours ( no true arcs ) causes my CAM software to create a high number of short lines. As a result, the G-Code has a lot of commands. Flashcut and Keyspan adaptor handle this throughput without error. I have not done many 3-D contouring programs and those
were not very complex. No problems were encountered.
Windows must be setup correctly. Turn off all the power saving features. Never sleep the hard drive. Never allow standby. I leave the screen saver active, but some say to disable it also. All background programs should be shutdown. Turn off automatic backups. Windows is easily distracted.
The USB adaptor has not degraded the machine performance. Since the laptop (600 MHz) is very slow by todays standards, I get better results using the adaptor.
I have run this same setup on a 2.6 GHz laptop also. The only difference is the Flashcut interface runs a lot faster, G-Code loads a lot faster. Communication to the controller is a pretty slow rate compared to user interfaces of todays software.
One last point of interest, the Keyspan adaptor solved the communication problem I had on a cnc four axes foam cutter. The controller would give timeout errors using the serial port on the laptop. When I switched to using the Keyspan adptor, the errors went away.