My USB to RS232 device has a "ready" light on it. When I put down the cover of my laptop, then later, pick it back up, the "ready" light is not on, and if I try USB to RS232 operations, my system hangs!
Interesting - the unit should reenumerate when you resume. A couple of questions:
1) If you unplug the box and plug it back in does it reenumerate and function properly? 2) Is a COM port open when you shut the lid of your laptop? 3) What applications (if any) are running when you go into suspend?
Just got back from a trip - sorry for the delay. I pulled out the Nat. Inst. box and replaced it with a low-cost usb to rs232 device (SIIG $29 per channel) - these work fine in my application. So I didn't get a chance to test unplugging it. I believe the COM ports were closed at the time of shutting the lid of my laptop. LabVIEW may have been running at times when I went into suspend. I still want to use the Nat. Inst. box under LabVIEW 7, and would still like to know how to resolve this problem! Thanks, Road Dog.
This problem may be related to a bug with the Windows power management that prevents composite devices like the USB-232 from properly waking up after a system suspend.
Try this: In the device manager, locate the USB root hub (there may be several). Right click>properties>Power Management tab. Uncheck "Allow the computer to turn off this device to save power" if the option is available.
Chris, I've never reloaded the USB-232 software or attached the box to my laptop since your reply, so I don't know if this was the problem or not. Thanks for the information, and whenever I do get around to using this box with my laptop, I'll definitely let you know what the story is on this.
