Chapter 16 PLC Function ApplicationsMS300
681
Example 6: Sequence control
If the N.C. contact of Y2 in the interlocking control configuration from example 5 is put in
series with the Y1 circuit, to create an AND condition for actuation of Y1 (see diagram
below), not only is Y1 a condition for the actuation of Y2 in this circuit, but the actuation
of Y2 also stops the actuation of Y1. This configuration confirms the actuation order of
Y1 and Y2.
Figure 16-42
Example 7: Oscillating circuit
Oscillating circuit with a period of ΔT+ΔT
The diagram below shows a very simple ladder diagram. When starting to scan the Y1
N.C. contact, because the Y1 coil has lost power, the Y1 N.C. contact is closed. When
the Y1 coil is then scanned, it is electrified, and the output is 1. When the Y1 N.C.
contact is scanned in the next scanning cycle, because the Y1 coil is electrified, the Y1
N.C. contact is open, the Y1 coil then loses power, and the output is 0. Following
repeated scanning, the output of Y1 coil has an oscillating waveform with a period of
ΔT(ON)+ΔT(OFF).
Figure 16-43
Oscillating circuit with a period of nT+ΔT
The ladder diagram shown below uses timer T0 to control coil Y1's electrified time. After
Y1 is electrified, it causes timer T0 to close during the next scanning cycle, which
causes the output from Y1 to oscillate as shown in the diagram below. The constant n is
the timer's decimal setting value, and T is the clock cycle of the timer.
Figure 16-44
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