User`s manual

NexSens Technology, Inc.
iSIC User‟s Manual 54
2.9 Digital Input\Output
Digital I/O uses a voltage signal to represent either a one or a zero. A “0” typically ranges from
0 volts to 0.8 volts while a “1” will range from 2.4 volts to 5 volts. These ranges are defined in
the TTL (Transistor-Transistor Logic) specification.
Environmental data loggers can use digital I/O ports for a variety of applications. A digital
output from a data logger may be used to control a relay that turns on a light, alarm, or
activates a pump. A level switch with digital outputs can interface directly with a data logger to
detect changes in level. For example, if water level drops below a set point, the switch output
changes from “0” to “1” thus notifying the data logger of a low level.