Jump Instructions and
Subroutine Programming
Chapter 11
113
Instruction overview:
Output instruction
Can jump 1 or more times to the label with the same identification
number.
Uses 1 word of memory
Has 2 digit octal identification number
Caution is advised when jumping over timers or counters.
Causes of run-time errors:
NOTE: Do not misuse the Jump instruction. Misuse generally results in
a run-time error which causes the processor to fault. Misuse of the Jump
instruction will cause the following run-time errors:
Jumping over a temporary end instruction
Jumping from main program into subroutine area
Jumping backward in memory
Jumping to an undefined label
CAUTION: The programmer should make allowances for
conditions which could be created by the use of the Jump
instruction. Jumped program rungs are not scanned by the
processor, so inputs are not updated and outputs remain in their
last state. Timers and counters cease to function. Critical rungs
should be reprogrammed outside the jumped section of the
program.
The Jump/Subroutine instructions are programmed from the industrial
terminal keyboard with the processor in program mode. When entered,
they are displayed as intensified and blinking. The reverse-video cursor
will position itself at the first digit of the identification number above
the instruction. It will continue to blink until the two-digit identification
number is entered. A zero must be entered in the first position. Refer to
Table 11.A for a complete summary of the Jump/Subroutine instructions.
There can be many combinations of multiple jumps to the same label in
the user program or subroutine area. Some of these combinations are
illustrated in Figures 11.3, 11.4, and 11.5.
11.1.1
Programming Jump/
Subroutine Instructions
11.1.2
Multiple Jumps to the Same
Label
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