WESTLOCK CONTROLS CORPORATION
280 N. MIDLAND AVE., STE. 258, SADDLE BROOK, NJ 07663 TEL: 201-794-7650 FAX: 201-794-0913
www.westlockcontrols.com
10/5/2013
TECH-477/D.W.O. 21424
Page 53 of 206
valve actuation to complete one or more time-critical applications. Each of these
applications is called Function Block Application.
A basic diagram for a simple device, called Compact Device e.g. Transmitter and actuator
is show below:
The device manager has the directory structure where each entry will point to a block or an
object inside of the device function block application.
The Physical block has a set of parameters to handle the device hardware itself. One
compact device has one physical block.
The transducer block has a set of parameters of the connection to the process. For
instance, type of sensor, characterization curve, calibration, diagnostics, and valve
signature.
The function blocks have a set of parameters executing the automation system. Examples
are: Analog Output (AO), Analog Input (AI), Digital Output (DO) and Digital Input (DI).
The function blocks shows the variables important for the automation system but it hide the
specific measurement or actuation variable. The measurement and actuation is executed
by the transducer block and the function block is linked with a transducer block via channel
parameter.
The channel parameter is configured to link a function block parameter with a transducer
block parameter.
8.3.1 Block Modes
Target Mode –
Writing to this field instructs the device to change to that specified
mode. The device will attempt to change to that mode. If it is successful, the
ACTUAL field changes to reflect the TARGET field.
Actual Mode –
This field displays the current operating mode of the function block
of this device.
Permitted Mode(s) –
This field displays a list of all allowable target modes for this
function block.
Normal Mode –
This field displays the mode that the function block is expected to
be in during normal use.