The analog output module is used to control valves, vents, actuators, and 0-20mA or 4-20mA current loops. A typical signal chain consists of DACs, references, and output signal conditioning circuitry. The signal conditioning circuitry usually consists of amplifiers, switches, and FET’s. Typical high end requirements are 16-bit DAC resolution and full isolation. The output ranges can be hard set or programmable. Low end requirements typically use lower resolution and accuracy DAC’s and do not always contain isolation.