Watlow ez-zone pm - A Conceptual View of the PM; Inputs

Watlow EZ-ZONE
®
PMI Controller • 10 • Chapter 1 Overview
Note:
The output cycle time will have a bearing on the life of mechanical relay outputs and can
be different based on the type of output ordered. The output cycle time can be changed
in the Setup Page under the Output Menu.
EZ-ZONE PM Default Configuration
Heat
Thermocouple Type J
Analog Input 1
PID
Controller
Heat
Loop 1
Input Sensor
Output
Function
Input
Function
Output 1
Process
Value
(PV)
Function
Off
A Conceptual View of the PM
The exibility of the PM software and hardware allows for a large range of congurations.
Acquiring a better understanding of the controller’s overall functionality and capabilities
while at the same time planning out how the controller can be used will deliver maximum
effectiveness in your application.
It is useful to think of the controller in terms of functions; there are internal and external
functions. An input and an output would be considered external functions where the limit,
PID or alarm function would be an internal function. Information ows from an input func-
tion to an internal function to an output function when the controller is properly congured.
A single PM controller can carry out several functions at the same time, for instance (but not
limited to), PID control, checking for a limit condition, monitoring for several different alarm
situations, etc... To ensure that the application requirements are being met, it is important
to rst give thought to each external process and then conguring the controller’s internal
functions to properly accommodate the application requirements.
Inputs
The inputs provide the information that any given programmed procedure can act upon. In a
simple form, this information may come from an operator pushing a button or from a sensor
monitoring the temperature of a part being heated or cooled.
Each analog input typically uses a thermocouple or RTD to read the process temperature. It
can also read volts, current or resistance, allowing it to use various devices to read a wide
array of values.
A PM with digital input/output (DIO) hardware includes two sets of terminals where each of
which can be used as either an input or an output. Each pair of terminals must be congured
to function as either an input or output with the direction parameter in the Digital Input/
Output Menu (Setup Page). Each digital input reads whether a device is active or inactive.
The Function or EZ Key/s (PM4/6/8/9 only) on the front panel of the PM also operates as a
digital input by toggling the function assigned to it in the Digital Input Function parameter in
the Function Key Menu (Setup Page).