Delta Electronics VFD-E manual Example 6 Sequential Control

Appendix D How to Use PLC Function

Example 5: Interlock control

X1

Y1

X2

Y2

X3	Y2	Y1	X1
			X3
			X2
			X4
X4	Y1	Y2	Y1
			Y2

The figure above is the circuit of interlock control. Y1 and Y2 will act according to the start contact X1 and X2. Y1 and Y2 will act not at the same time, once one of them acts and the other won’t act. (This is called interlock.) Even if X1 and X2 are valid at the same time, Y1 and Y2 won’t act at the same time due to up-to-down scan of ladder diagram. For this ladder diagram, Y1 has higher priority than Y2.

Example 6: Sequential Control

X1 X3 Y2

Y1 Y1

X2 X4 Y1

Y2 Y2

Example 7: Oscillating Circuit

The period of oscillating circuit is ΔT+ΔT

Y1

Y1

If add normally close contact Y2 into Y1 circuit to be an input for Y1 to do AND function. (as shown in the left side) Y1 is an input of Y2 and Y2 can stop Y1 after acting. In this way, Y1 and Y2 can execute in sequential.

Y1

T T

The figure above is a very simple ladder step diagram. When starting to scan Y1 normally close contact, Y1 normally close contact is close due to the coil Y1 is OFF. Then it will scan Y1 and the coil Y1 will be ON and output 1. In the next scan period to scan normally close contact Y1, Y1 normally close contact will be open due to Y1 is ON. Finally, coil Y1 will be OFF. The result of repeated scan, coil Y will output the vibrating pulse with cycle timeΔ T(On)+ΔT(Off).

D-16 Revision June 2008, 04EE, SW--PW V1.11/CTL V2.11