Overview

In Siemens SIMATIC Manager (used with STEP 7 for S7-300/400 PLCs), a simple one-line Ladder Logic program with a single digital input and a single digital output can be written as follows:

One-Line Ladder Logic:

ladder
|----[ I0.0 ]----( Q0.0 )----|

Explanation:

• I0.0 – This is the digital input (e.g., a pushbutton or sensor).

• Q0.0 – This is the digital output (e.g., a lamp or motor).

• When I0.0 is ON, Q0.0 is energized (turned ON).

• When I0.0 goes OFF, Q0.0 turns OFF.

This is the simplest form of ladder logic and is often used for introductory tasks, such as turning on a light with a button. Would you like to see this in a function block or symbolically named format too?