How to write PLC Ladder program using Allen Bradley- RSLogix


#1

Entering the LADDER program:
A Personal computer is most often used to enter the ladder program.

The computer is adapted to the particular PLC model using the relevant programmable control software and driver software.

RSLogix Main Screen:
Different Screens, toolbar and Windows dialog boxes are used to navigate through the Windows Environment.

Bit Instructions Tool Bar:


To place an instruction on a rung, click its icon on the toolbar and simply drag the instruction straight off the toolbar onto the rung of the ladder

Select Processor type Screen:
The Programming software needs to know what processor is being used in conjunction with the program.

You simply scroll down the list until you find the processor you are using and select it.

I/O Configuration Screen:

The I/O Screen lets you click or drag-and-drop a module from an all inclusive list to assign it to a slot in your configuration.

Data File Screen:

Data file screen contains data that are used in conjunction with ladder program instructions.These include:
Input
Output
Timer
Counter
Integer
Bit

Monitoring a ladder logic Program:
Operation of the logic is apparent from the highlighting of rungs of the various instructions on screen, which identifies the logic state in real time and has logic continuity.

Highlighted rungs indicate the instruction is true

Modes of Operation:

A processor has basically two modes of operation:
1)Program Mode
2) Some variation of Run mode

Program Mode:
Enter a new program
Edit or update an existing program
Upload files
Download files
Document programs
Change software configurations
When the PLC is switched into the program mode , all the forces from the PLC are forced OFF regardless of their rung logic status, and the ladder I/O scan sequence is halted

Variation of the RUN Mode
Run Mode- it is used to execute the user program .Input devices are monitored and output devices are energised accordingly

Test Mode- It is used to operate or monitor the user program without energising any output
Remote Mode-Allows the PLC to be remotely changed between program and Run mode by a personal computer connected to the PLC processor