Chapter Outline
6.1 Introduction
6.2 Creating PLC Ladder Logic Diagrams from Relay Logic Diagrams
6.3 Programming Ladder Logic Diagrams with Normally Open and Normally Closed Switches
6.4 Programming Ladder Logic Diagrams with Normally Open and Normally Closed Contacts
6.5 PLC Program Scan Time
6.6 PLC Program and Data Files
6.7 Programming Ladder Logic Diagrams with Latch and Unlatch Instructions
6.8 Loading and Troubleshooting PLC Ladder Diagrams in Run Mode
6.9 Using PLC Force Instruction for Troubleshooting
6.10 Creating and Printing PLC Program Reports
6.11 Using Utility Instructions to Save and Retrieve PLC Programs
6.12 Using LogixPro Simulator to Create Ladder Logic Diagrams
Technical Terms
rung comments
immediate input with
mask (IIM)
immediate output with
mask (IOM)
project tree area
main program fi le
PLC project
subroutine program fi les
PLC Programming
Chapter 6
input (I)
examine if closed (XIC)
examine if open (XIO)
output (O)
status (S2)
timers (T4)
counters (C5)
control (R6)
integer (N7)
bit (B3 and B10)
run mode
online monitor mode
offl ine mode
online mode
enable force
channel one
channel zero
instruction comments
Learning Objectives
After completing this chapter, you will be able to:
• List the rules for creating a PLC ladder logic diagram.
• Convert a relay logic diagram to a PLC ladder logic diagram.
• Create ladder logic diagrams when the PLC is in the offline mode.
• Download PLC ladder logic diagrams and test them on a trainer.
• Use the force instruction for troubleshooting.
• Create and print program reports.
• Save and open ladder diagram project files.
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