Software for Education and Industry

PLC Programming


Allen-Bradley RSLogix® Micro


Tired of wading through mounds of technical manuals or myriads of websites to learn how to program a PLC? This program shows you step-by-step how to program an Allen-Bradley Micrologix® PLC using free Allen-Bradley's RSLogix® Micro Starter Lite software.

Simply download the free Allen-Bradley RSLogix® Micro Starter Lite software at then follow the exercises in this program to learn how to program PLCs using Allen-Bradley's RSLogix® software. You do not need an actual PLC to use this program.

This program is written in everyday, easy to understand language and tells you what you need to know when you need to know it.  It is written in .html format so you can use your favorite internet browser with hyperlinks, bookmarks, and word searches, and requires no software installation on your computer.  Just insert the CD, double click on the Table of Contents.html and your internet browser launches the program.

This program explains every Micrologix 1000 instruction and shows you:

This program is written by a Professional Engineer with 14 years industrial experience and 20 years experience teaching electrical engineering technology at the college level.

PLC Programming


Allen-Bradley RSLogix® Micro

Table of Contents


              1.  Introduction

                        What this program includes

                        What you need

                        Types of Allen-Bradley Micrologix PLCs

              2.  Launching RSLogix (and optionally RSLinx)

                        Download the RSLogix and (optional) RSLinx

                        Start RSLinx (optional)

                        Start RSLogix

                        Select a Processor

                        Add a Rung

                        Save your program

               User Instructions and Descriptions

              3.  Programming Your First Instruction (XIC)

                        XIC instruction

                        Add a Symbol

                        Examine the Input Data File

              4.  Adding Descriptions to Instructions

                        Open the Edit Descriptions window

                        Add descriptions to the instruction

              5.  Programming a Complete Rung (OTE, XIO, XIC)


                        XIO instruction

                        XIC instruction

                        OTE instruction

                        Add a branch and seal-in contact

                        Verify the project

                        Examine the Output Data File

                        Add a B3 binary output

                        Download the program to the PLC (optional)

                        Download the program to the emulator (optional) 

                        Force the Stop switch on


               6.  Latch and Unlatch Relays (OTL, OTU)


                        Add a Latch switch

                        OTL  instruction

                        Add an Unlatch switch

                        OTU instruction

               Timers and Counters 

              7.  Timers (TON, TOF, RTO, RES)


                        Add a Start Timer switch

                        TON instruction

                        Examine the T4-Timer Data file

                        Add some timer contacts

                        TOF instruction

                        Add some TOF timer contacts

                        RTO instruction

                        RES instruction


               8.  Counters (CTU, CTD, RES, HSC, RAC)


                        CTU instruction

                        CTD instruction

                        HSC, HSE, and HSD instructions

                        Examine the S2-Status File


                9.  Immediate Input and Output (IIM, IOM)


                        IIM instruction

                        IOM instruction

              Compare Instructions

             10. Compare Instructions (LIM, MEQ, EQU, NEQ, LES, GRT, LEQ, GEQ)


                        LIM instruction 

                        MEQ instruction 

                        EQU instruction 

                        NEQ instruction 

                        LES instruction

                        GRT instruction

                        LEQ instruction 

                        GEQ instruction

            Compute/Math Instructions

            11.  Compute/Math Instructions (ADD, SUB, MUL, DIV, SQR, NEG, TOD, FRD)

                        ADD instruction

                        Examine the S2-Status data file

                        How a PLC stores negative numbers

                        SUB instruction

                        MUL instruction

                        DIV instruction

                        SQR instruction

                        TOD instruction

                        FRD instruction


            Move/Logical Instructions


            12.  Move/Logical Instructions (MOV, MVM, AND, OR, XOR, NOT, CLR)

                       MOV instruction

                       MVM instruction

                       AND instruction

                       OR instruction

                       XOR instruction

                       NOT instruction

                       CLR nstruction


           File Manipulation Instructions


           13  File/Misc Instructions (COP, FLL, DDV, SCL, INT, STE, STS, STD)

                      COP instruction

                      FLL instruction

                      DDV and OSR instructions

                      SCL instruction

                      STI interrupt


           14. File Shift/Sequencer Instructions (BSL, BSR, SQC, SQL, SQO, FFL, FFU, LFL, LFU)

                      BSL instruction

                      BSR instruction

                      SQO instruction

                      SQL instruction

                      SQC instruction

                      FFL and FFU instructions

                      LFL and LFU instructions


            Program Control Instructions    


            15.  Program Control Instructions (JMP, LBL, JSR, RET, SBR, TND, MCR, SUS)                    

                      JMP and LBL instructions

                      JSR, SUB, and RET instructions

                      TND instruction

                      MCR instructions

                      SUS instruction


            Advanced Math Instructions


            16. Advanced Math Instructions (DCD, ENC)

                     DCD instruction

                     ENC instruction


Sample Exercise


 Chapter 14.  File Shift/Sequencer Instructions


Step 3) - Add a switch and a BSR  instruction

BSR (Bit Shift Right) is an output instruction that shifts a data word one bit to the right each time the instruction is energized.  It is useful for tracking parts down an assembly line, for instance, where each bit represents a part.

Add a switch and a BSR instruction to a new rung as shown below.  The BSR  instruction is in the File Shift /Sequencer category of instructions as shown circled in red.  Enter N7:1 for the File, R6:1 for the Control, I:0/3 for the Bit Address, and 5 for the Length of the BSR  instruction.  

Append another rung and add a normally open contact with address R6:1.UL in series with an output O:0/1. 

Your screen should look like the following:

After a BSR instruction has been added

When the program is run, each time I:0/2 is closed the following will happen:


1) bit 0 of N7:1 will be sent to bit 10 of word R6:1, which is also called R6:1.UL

2) all the bits of word N7:1 will be shifted one position to the right, and 

3) the status of Bit Address I:0/3 will be brought into bit 4 of word N7:1. 


This operation is shown graphically below:

If a number greater than 16 is entered for the Length of the instruction, the shift will occur across word boundaries, but R6:X.UL will always be energized by the least significant bit of the word entered as the File parameter. 

Assuming N7:1 initially contained all zeros, the following screen shot shows the N7:1 word after switch I:0/2 has been closed 5 times with switch I:0/3 closed each time. On the next closure of switch I:0/2, the 1 from bit 0 of word N7:1 will be sent to R6:1.UL, turning on output O:0/0.

N7:1 word after switch I:0/2 has been closed 5 times with I:0/3 closed

Hardware/Software Requirements:

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