Glossary · Automation fundamentals, platforms and components
Initialization
Also known as: Startup initialization
German: Initialisierung
In programming and automation, initialization is the assignment of defined starting values to variables, devices or systems before normal operation begins, for example at power-up, controller startup or first call of a block.
- Automation components
In one sentence
Initialization assigns defined starting values to variables, devices or systems before normal operation, such as at power-up or startup.
Example
At startup, the PLC's startup routine sets all sequence steps to their initial state and waits for the operator to home the axes.
How it applies
- Engineering: IEC 61131-3 variables have initial values, and retentive variables keep their values over a power failure. The programmer decides which values are reset and which are retained.
- Safety: Startup behavior must not cause Unexpected startup. Outputs should start in a Safe default state, and restarting after power return usually requires an operator command.
- Documentation: Operating instructions should describe what the machine does after power-up and after a power failure, including homing and reference runs. Software documentation should list retained data.
Initialization vs. reset
Initialization establishes starting values when a system or program starts. A reset returns a function or device to a defined state during operation, often after a fault. The two may use the same code but occur in different situations and require different documentation.