Analog I/O devices process analog signals (e.g., output of transducers) and output the results in analog format. There are several types of analog I/O devices. Examples include analog modules, analog I/O boards, analog I/O cards, analog input cards, analog output cards, and USB analog I/O. An analog I/O device is a device that supports both analog input and analog output. Analog I/O modules are available in different models that provide eight channels of line-level analog to digital conversion and also eight channels of line-level digital to analog conversion. An analog I/O board allows the data acquisition system to record analog signals from any instrument and it generates the analog signals for any instrument. An analog I/O card is the circuit on a printed circuit board (PCB) that is capable of supporting both the analog input as well as output. An analog I/O card is analog output card which is used in applications where the outputs other than on and off states are generated. A USB analog I/O is a device that is used to interface a PC with a number of real world analog inputs or outputs.

Analog I/O devices are available with a variety of specifications. An analog I/O device 1/2-channel output modules produces output current of 0/4.20 mA and output voltage of -10 to +10 V DC. Some specifications of the 96 KHz series card are 24-bit, 96 kHz eight-channel line-level analog input card and has maximum input level of +18db before clipping. An analog I/O module uses a LED metering and a four- position gain settings. A type of Analog I/O module is DC current input module which has four input channels. In this input module, the input current ranges from 0 to 20 mA DC and it requires 10V to 36V DC power. Another type of Analog I/O module is a DC Voltage output module with discrete outputs. This output module also produces four channel analog output and has the output range of 0 to 10 V DC. The specifications of a SUB BUS 64 an analog I/O board is that it reads data asynchronously. Analog I/O boards provide serial interface to high resolution serial A/D converters. An analog I/O card consists of the analog input card at the input and analog output cards at output. An analog input card is designed to acquire analog data even in a harsh electrical environment with computers and other compatible devices. It provides four isolated 12-bit differential input channels with ± 1 conversion accuracy. Analog input cards have selectable input ranges which are 0-1V, 0-5V, 0-10V, ±5V, ±10V, 0-20 mA and 4-20 mA. An analog output card converts the digital value generated by software into analog current or voltages that are used to control brightness of light, to control frequency inverters and motor controlled equipments. Analog output cards are used to obtain many outputs that are used to excite analog output transducers. Analog I/O devices use USB analog I/O functions in many USB-based acquisition products. Analog I/O devices can be designed and manufactured to meet most industry specifications.

Analog I/O devices are useful in many applications like PC based measurement, analysis, control and monitoring. Analog I/O devices are also used for programmable voltage sources or current sink, servo control, and process control.