Rockwell Automation 2711 PANELBUILDER SOFTWARE USER MANUAL - Manual (Page 108)

Planning Your Application
Chapter 4
4-33
The Control List Selector Without Enter Button has been defined as a
five-state object using the bit position data type. Thus, there is a string of
four bits that the PLC controller uses to determine the current selection.
When the operator uses the UP and DOWN buttons, the PanelView
terminal turns off the current bit; turns on the next higher or lower bit in
this bit string; and scrolls the highlight bar up or down through the
selections.
When the operator presses the ON or OFF button, the PLC program checks
which of the five Control Selector bits is on. It then turns the related pump
on or off.
Each Multi-State Indicator has a PLC output bit associated with it. The
PLC program sets the bit on when the pump is on, and sets the bit off when
the pump is off. The PanelView terminal monitors these bits, and displays
the ON or OFF label depending on the state of each bit.
Now for the five Numeric Displays. In this sample application we’ve
restricted ourselves to using one quarter rack. Each Numeric Display
requires a full PLC word. If you were restricted to discrete addressing, a
quarter rack wouldn’t be adequate; at least a 3/4 rack would be necessary.
The quarter rack limitation can be met by using a block transfer file.
In defining the block transfer file, a control byte was assigned in both the
Input and Output section of the image table. This is noted in the Discrete
I/O Usage Worksheet. You can’t use this control byte for any other
purpose. Program your PLC block transfer instruction to use this control
byte.
The Text objects, the Box, and the Return to Previous Screen button don’t
change state or communicate with the PLC controller. Therefore, they are
not included on the completed Object Address List or the I/O Usage
Worksheet.