Digital I/O refers to digital inputs (I) and digital outputs (O). The digital I/O on a data acquisition board or card is basic logic level digital signals.

Digital input voltage levels for the On-State or Logic Code 1 are typically from 2 to 5 volts. Digital input voltage levels for the Off-State or Logic Code 0 are typically from 0.8 to 0.0 volt.

Digital output voltage levels for the On-State or Logic Code 1 are typically from 3 to 5 volts. Digital output voltage levels for the Off-State or Logic Code 0 are typically from 0.4 to 0.0 volt.

A standard data acquisition board or card may have 4, 8, 16, or 32 lines or channels of digital I/O, and can be in most combinations of input and output channels. However, for more complex applications, complete standalone I/O boards are available with 96 channels of I/O. These special-purpose boards might provide both logic-level and high-current drive outputs (64 mA sink, 15 mA source), compatible with relay and SSR and relay racks.

In addition to multichannel I/O with logic-level and high-current drive outputs, the I/O family of products includes a lot more. Included in this family you will find multichannel counter/times (with and without crystal control oscillator), 2-4 channel quadrature encoder boards, 16-channel electromechanical relay boards, and 32-bit interrupt vector input boards.

Measurement Computing Corporation offers the largest selection of PC-based data acquisition and measurement products. Shop our online catalog by selecting a category above. From PCI, USB, PC/104, ISA, and PCMCIA bus boards to external systems based on USB, RS-232, RS-422, RS-485, and GPIB interfaces; Measurement Computing has everything you need for your PC-based data acquisition and control applications.