Quality factor

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In a distributed system where information (signals) is sent between different control modules in a network, it is usually the control module that generates/creates information (the signal) that knows the quality of the information that is sent. To be able to inform receiving control modules about the quality of information, a quality factor (Q-factor) is sent over the network at the same time as the information (signal). The quality factor describes status of the information (signal). For example, if the signal is defective due to a faulty sensor, a receiving control module can use the quality factor to decide if the control module shall take any action (e. g., reconfiguration).

The quality factor can be of the following status:

OK
The value indicates that the signal is normal and shows a credible status and accuracy.
Outside specified range
Even though the value indicates that the signal is normal and may be usable, some fault has been detected that indicates that accuracy has been reduced so that performance may be affected or instability can occur.
No data found
The value indicates that the signal has its initial start-up value and has not yet had time to receive measured or calculated value. This may occur when the control module's start-up process is not completely finished. As soon as the control module has started, the signal shall have a correct value. Receiving control module has a built-in delay to wait for correct signal.
No data exists
The value indicates that the signal is faulty. This prevents the signal from being used by receiving control modules.

Summary of quality factor that may apply.

Sending control module	Receiving control module and its function
Status	"Common" control module	Control module with high demand for accuracy
OK	Normal function	Normal function
Outside specified range *	Normal function	Controlled limitation of performance may occur *
No data found	Normal function	Normal function
No data exists *	Limited or lost performance/lost function *	Limited or lost performance/lost function *

* Diagnostic trouble code may be stored.