An analog output is the part of a control system that sends analog control signals to something that takes action such as a valve actuator, linear actuator, or rotary actuator. This involves taking digital data from the microcontroller, generating an analog signal from that data using a DAC, then adjusting the gain and offset of this signal to one of the voltage or current signal ranges shown on this slide. An analog output card must be robust, it should be able to detect faults and protect against them where possible. Galvanic isolation for both data and power is ultimately needed to ensure that voltage spikes from the field or actuator side never damage the central microcontroller. It is not shown on the slide, but a smaller sub-micro can often be found between the data isolation and DAC.