Delta Electronics VFD-E manual Example for Designing Basic Program

Appendix D How to Use PLC Function

on analyzing other ladder diagram. You can recognize the command MRD by the symbol “├”.

9.MPP command is used to read the start status of the top level and pop it out from stack. Because it is the last item of the horizontal line, it means the status of this horizontal line is ending.

You can recognize this command by the symbol

“└”. Basically, that is all right to use the above

method to analyze but sometimes compiler will

omit the same outputs as shown at the right.

MPS

MPS

MRD

MPP

MPP

D.3.4 The Example for Designing Basic Program

„Start, Stop and Latching

In the same occasions, it needs transient close button and transient open button to be start and stop switch. Therefore, if you want to keep the action, you should design latching circuit. There are several latching circuits in the following:

Example 1: the latching circuit for priority of stop

When start normally open contact X1=On, stop normally contact X2＝Off, and Y1=On are set at the same time, if X2=On, the coil Y1 will stop acting. Therefore, it calls priority of stop.

Example 2: the latching circuit for priority of start

When start normally open contact X1=On, stop normally contact X2＝Off and Y1=On (coil Y1 will be active and latching) are valid at the same time, if X2=On, coil Y1 will be active due to latched contact. Therefore, it calls priority of start.

Y1 X2

X1

X1 X2

Y1

Y1

Y1

D-14 Revision June 2008, 04EE, SW--PW V1.11/CTL V2.11