Rockwell Automation 1772-LV Mini-PLC - 2/15 Programmable Controller (Series B) Programming and Operations User Manual
Page 121
Programming Applications
Chapter 9
9Ć4
Rungs 3 thru 5: Convert Celsius temperature to Fahrenheit temperature
exactly as in application one.
Rung 6: The return instruction signals the processor to return to the main
program area.
CAUTION: Allowances should be made for conditions which
could be created by the use of the jump instruction. Jumped
program rungs are not scanned by the processor so that input
conditions are not examined and outputs that are controlled by
these rungs remain in their last state. Timers and counters cease
to function. Critical rungs should be reprogrammed outside the
jumped section in the program zone.
Refer to Figure 9.3.
This application illustrates the program control instructions, master control reset
(MCR) and zone control last state (ZCL).
Common applications such as varying either packaged size or recipe ingredient
use these instructions; packaging a product in two different sizes or converting a
food product to a dietary food product by changing its sugar content would be
examples of applications.
Before you program these two instructions you must think about how you
would want your outputs to react when changing your process.
Application Three