In cases where a computer and the device to be communicated with are much far apart, RS-422 is the preferred serial standard. Due to differential signaling, the signal is less prone to noise and may be sent on cables as long as 1500 meters. Maximum data rate is 10 Mbps at 12m and degrades with cable length. You can use a commercially available USB-422 adapter or make one yourself to send and receive RS-422 signals on your computer.
