The 104-IDI-48 series of PC/104 isolated digital I/O boards are 48-channel utility boards featuring 48 individually optically isolated digital inputs. These boards are suitable for use in control and instrumentation applications where high-voltage protection is required. Individual channel-to-channel isolation allows every channel to be physically and electrically separated from the others. Enabled inputs feature a change-of-state detection capability that provides a means to automatically interrupt the host computer in real time. When one or more input bits change state, an interrupt is generated to automatically wake up the application.