Rievtech PR-12 Series, User Manual And Programmers Manual

Page: 64 / 260

57
move,because there is no need to worry about addressing conflicts.
interrupt routine
You can write an interrupt routine to handle some predefined interrupt events:The
interrupt routine is not called by the main program;When the interrupt event occurs,
it is called by the PLC operating system.Interrupt routine is best to use local variables.
You can use a local variable table to ensure that your interrupt routine uses only
temporary memory.
5.5 How to enter the ladder logic program
5.5.1 How to build a new project
Click
，
Or click on the file drop-down menu Icon
，
Create a new project.
Open an existing project
Click the
“
file
”
icon, select
“
open
”
or
“
open the PWM file
”
.
5.5.2 Ladder logic element and its working principle
Ladder logic (LAD) is a graphical language which is similar to the electrical relay
diagram.When you write a program in LAD, you use graphical components and
arrange them into a logical network.The following component types are available for
use when you build a program:
contact the switch which power supply can pass through.When the normally
open contact logic is 1 and the normally closed contact logic is 0, the power supply
can pass through these contacts.
coil The coil represents the output.
Block Each block represents a function.
The network is composed of the above elements.The power supply from the left side
of the power rod flows through the closed contact to charge the coil or the block.