Portland Community College | Portland, Oregon

Students will write ladder logic programs using a PLC simulator program on a PC. Instructions include bit, program control, timer, comparison, counter, and sequencer instructions. Depending on availability of time, data handling and bit shift instructions may also be covered.

Upon successful completion students should be able to:

Identify basic components of a PLC and describe their functions.
Create, edit, down load, run PLC programs.
Monitor variable values in real time in program execution.
Read and understand simple ladder logic programs. Effectively write basic and intermediate level PLC programs.
Perform simple debugging of programs.
Provide proper documentation to programs.

Instructor introduces various PLC programming concepts in lectures first. Students will then practice applying the concepts by writing programs to solve
practical problems in the labs. Before the lab, instructor will introduce the lab project and provide hints for students. Students will be asked to complete the programs as homework if they are not done in the lab. Instructor will discuss with students solutions to the labs afterwards in class.

Students will be graded on their programs. A practical exam involving the writing of a program may also be required at the end of the term.

1. PLC Hardware Intro
a. Describe the PLC architecture
b. Describe the PLC program execution cycle
c. Describe various Data Memory Area and file types
d. Be able to address digital I/O lines, bits in data memory and
variables.
2. Ladder logic intro
a. Explain the operation of ladder/relay logic
b. Be able to navigate in the LogixPro software interface
c. Familiarize with the LogixPro I/O Simulator
d. Create, edit, “down load”, run LogixPro programs
e. Effectively use N.O switch, N.C. switch and coil output instructions.
3. File Types and Organization
a. Explain the various file types, their purpose, and their relation to each
other: project file, processor file, database file, program file and data
file.
b. Be able to describe the purpose, symbol, content, structure, and addressing of each data file type, including output, input, bit, integer,floating point, counter, timer, processor status, and control file.
c. Be able to monitor variable values in real time in program execution using the Data Table function.
4. Bit Instructions: explain and demonstrate the usage of each of the following bit instructions: XIC, XIO, output coil, latch, unlatch, and one shot.
5. Program Control Instructions:
a. Be able to use JMP and LBL instructions to jump over rungs
b. Be able to use MCR instruction to shut down operation of a section of a program
c. Be able to create subroutines
d. Be able to call subroutines in main ladder program.
6. Timer Instruction:
a. Effective use on delay timer instruction TON
b. Effective use off delay timer instruction TOF
c. Be able to describe when retentive timer is used
d. Effective use retentive timer instruction RTO
e. Effective use timer reset instruction RES
f. Explain the significance and be able to track status bits of various timer instructions.
7. Comparison Instructions:
a. Effectively use comparison instructions: EQU, NEQ, LES, GRT, LEQ, GEQ
b. Effectively use limit test instruction: LIM
c. Effectively use masked comparison instruction: MEQ
8. Counter Instruction:
a. Effectively use Counter Up (CTU) instruction
b. Effectively use Counter Down (CTD) instruction
c. Effectively use Reset (Res) instruction
9. Sequencer Instructions:
a. Describe situations in which sequencer instructions are needed
b. Effectively use SQO instruction
c. Effectively use SQC instruction
10. Data Handling Instructions: (optional if time is available):
a. Effectively use MOV instruction
b. Effectively use MVM instruction
c. Effectively use COP instruction
d. Effectively use FRD and TOD instructions
11. Bit shift instruction: (optional if time is available)
a. Effectively use BSL and BSR bit shift instructions