Agilent Technologies produce several digital I/O (input / output) modules that connect to a computer via a USB cable.
The U2100A are 32 channel USB data acquisition modules with integral terminal blocks.
The U2600A are 64 channel USB data acquisition modules that require a cable and terminal block for connection of external signals. The U2600A series may also be installed in the Agilent U2781A six slot chassis.
The U2751A is a 4x8 switch matrix module for use with other instruments such as Agilent USB oscilloscope or data acquisition modules