When looking for a "1", which symbol is used?

In programmable controller systems, symbols play a crucial role in defining the states of inputs and outputs. The symbol used to represent a "1" typically indicates an energized or true state in ladder logic diagrams.

The symbol that corresponds to a "1" is commonly a bracket symbol "] [". This representation reflects a closed contact in the context of ladder logic, meaning that the contact is closed and current is able to flow through it, which signifies an activated or high state. Therefore, when searching for a "1", you specifically look for these symbols to determine whether a condition is true or the input is active.

Understanding this context is helpful when interpreting and designing ladder logic diagrams, as it directly affects how the control systems will operate in response to various inputs. The other symbols do not reflect the energized state typically associated with a "1".