Output Override and I/O Update Instructions
Chapter 7
76
The Immediate Output instruction updates one module group with data
from one output image table word ahead of the normal scan sequence
(Figure 7.4).
The Immediate Output instruction is programmed as an output instruction
in the ladder diagram rung. This instruction is executed when rung
conditions allow logic continuity. Unconditional programming can also be
used to cause the module group to be updated during each program scan.
Program the Immediate Output instruction only when necessary. This
depends on the response time of output modules and devices, and on the
position of the rungs addressing the module group.
The Immediate Output instruction should be programmed just after the
rungs that control the bits in the addressed output image table word.
In programmable controller applications, this instruction only gives a slight
advantage when entered near the end of the program scan, since output
data will soon be updated in the I/O scan. This instruction is best applied
when entered near the middle of the user program.
7.2.3
Immediate Output
Instruction
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