Writing Ladder Logic

In this chapter, we will look at the history of ladder logic and the development of the International Electrotechnical Commission (IEC) standard programming languages. Then, we will jump into the ladder logic programming by creating a simple pump control program. We will demonstrate how to buffer inputs and outputs in our ladder logic code and discuss the importance of this process. Finally, we will explore the new program parameter features in Logix Designer version 24 (and higher) and how they can be used to buffer values and significantly reduce the amount of ladder logic required for a program.

This chapter will cover the following aspects of ladder logic:

• Ladder Logic overview
• Understanding IEC 61131-3
• Understanding IEC programming logic
• Programming Ladder Logic
• Buffering module I/O data
• Buffering using program parameters.
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