Editing Programmable logic controller (section)

===Discrete and analog signals===
[[Digital signal|Discrete (digital) signals]] can only take ''on'' or ''off'' value (1 or 0, ''true'' or ''false''). Examples of devices providing a discrete signal include [[limit switch]]es and [[photoelectric sensor]]s.<ref name=":8">{{Harvnb|Bolton|2015|pp=23–43}}</ref>

[[Analog signal]]s can use voltage or current that is analogous to the monitored variable and can take any value within their scale. Pressure, temperature, flow, and weight are often represented by analog signals. These are typically interpreted as integer values with various ranges of accuracy depending on the device and the number of bits available to store the data.<ref name=":8" /> For example, an analog 0 to 10&nbsp;V or 4-20&nbsp;mA [[current loop]] input would be [[analog-to-digital converter|converted]] into an integer value of 0 to 32,767. The PLC will take this value and translate it into the desired units of the process so the operator or program can read it.