System state information is often used to benchmark the reliability of a system. Therefore on a time scale it is estimated how long the system was productive, defective or in maintenance. To support this, a system should be able to publish its current state in a way enabling a client to do such estimation.

This standard follows the scheme of 6 basic system states defined by SEMI E10 standard (SEMI E10: Specification for Definition and Measurement of Equipment Reliability, Availability, and Maintainability (RAM) and Utilization). The following diagram shows how the total time of existence of a system is divided into different categories. From the left to the right the model gets more detailed.

Table 137 – E10 system states

E10
Total Time	Operations Time	Uptime	Manufacturing Time	Production	PRD
				Standby	SBY
			Engineering		ENG
		Downtime	Scheduled Downtime		SDT
			Unscheduled Downtime		UDT
	Nonscheduled Time				NST

If the optional SystemState variable exists on the server, the vision system shall continuously map its internal state to one of the six generic states on the right. This current state shall be published in the SystemState variable in the interface.