Allen-Bradley PLC-2/30 - Special Programming Techniques

Chapter
19
191
Special Programming Techniques
There are several programming techniques that offer versatile control of
the process of machine operation. They include:
One-Shot
The one-shot programming technique uses a scan counter to set a bit on for
one scan only. There are two types of one-shots that can be programmed.
Leading Edge
Trailing Edge
A leading edge one-shot is used to set a bit on for one scan when the input
condition has made a false-true transition. The transition represents the
leading edge of the input pulse. The programming for a leading edge
one-shot is shown in Figure 19.1.
Figure 19.1
Leading
Edge OneShot
Input Pulse: Bit 112/04
Oneshot Bit: Bit 203/00
||
04
112
||
00
Application Program...
203
( SCT )
203
PR 002
AC 000
ON
OFF
ON
OFF
One Scan
Leading Edge
19.0
General
19.1
One Shot
19.1.1
Leading Edge OneShot
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