Controls

Definitions

Analog Signal

An analog signal
varies in proportion to t he m on itored source. It quant ifies values between
operating limits. (Example: A temperature sensor is an analog device because its resistance
changes in proportion t o the temperature, gene r at ing many values.)

Digital Signal

A digital (discrete) signal
is a 2-positi on representati on of the value of a monitored source.
(Example: A switch is a digital device because it only indicates whether a value is above or
below a set point or boundar y by ge nerating an on/off, hig h/low, or open/closed sig nal.)

Volatile Memory

Volatile memory
is memory incapable of being sustained if power is los t and subsequently
restored.
CAUTION CAUTION
!
The memory of the PSIO and LID modules are volatile. If the battery in a module
is removed or damaged, all programming will be lost.