how to send a signal through a usb to a hardware device and make a LED glow

how to send a signal through a usb port to a hardware device and make a LED glow

[Daniel Shub]

How is the LED connected to the usb port?

Answer 1

[Walter Roberson]

USB is by definition a serial bus; any information sent over the bus is only present on the bus for a small fraction of a second. You thus cannot send and hold a signal via USB. Instead you would have to send data that the destination hardware interpreted as indicating the appropriate LED state.

There are suitable USB-compatible devices available: see http://www.mathworks.com/matlabcentral/answers/18366-how-to-send-a-signal-to-usb