The I.P.O Principle

The I.P.O. Principle

Control Modules receive information from sensors advising them of certain operating conditions. This information is identified as Input to the control modules. The Input continually informs the control modules of conditions that may be changing.

The control module then process the Input information comparing it to programmed responses or commands based on every possible operating condition. The control module decides based on the programming and the Input conditions which Output signal to operate.

The control module, based on the processing that has occurred, then sends a signal to a component changing the status of that component. The components respond to the Output signal of the control module.

This is known as the I.P.O. Principle.

I.P.O.




- Status of switch is changed.
- Changing switch status is sent to processor.
- Processor looks at conditions which must be met.
- If the processor deems the conditions for switch status change are met, a relay is signaled via a ground signal.
- The relay is energized, the points are closed and the light bulb glows.


NOTE: The processor looked at other inputs before making the decision to activate the relay.


Any device controlled by a processor requires input to the alert the operating program of a condition. The program processes the input information and logically activates an output of a component.

All BMW control systems are explained by the IPO principle. It is the key to understanding all BMW control system technologies.