SEMI SECS/GEM Standard Overview

SECS/GEM is a connectivity standard developed by Semiconductor Equipment Materials Initiative, or SEMI. This connectivity standard is used to enable communication between equipment, such as etch, deposition, and lithography, and the host's factory network.

SECS is an acronym for Semiconductor Equipment Communication Standard. GEM refers to the SEMI connectivity standard E30 and is defined as the Generic Model for Communications and Control of Manufacturing Equipment.

Generally speaking, the SECS/GEM defines messages, state machines and scenarios to enable factory software to control and monitor manufacturing equipment. This is formally designated and referred to as SEMI connectivity standard E30.

Download the Cimetrix SECS/GEM Standard white paper

SECS/GEM SEMI Connectivity Standard E30

In a factory SECS/GEM implementation, there are two parties - the host and the equipment. The equipment runs software on one of its computers that must implement and comply with SEMI E30. The manufacturer (factory) runs host software that establishes communication with the equipment's interface.

A host does not have to comply with the connectivity standard since they only set equipment expectations. However, in order to make use of the interface, a host must implement the host-side of the communications. SECS/GEM sets clear equipment behavior expectations for each possible host message.


The SECS/GEM SEMI connectivity standard defines how an equipment and host initially establish communication. It also defines how communication is re-established when communication is broken. An online identification method verifies the equipment's hardware and software identity. Terminal service features allow the host operator and equipment operator to exchange text manually typed at a console.


The SECS/GEM SEMI connectivity standard outlines a control state model to define the level of cooperation between the host and equipment operator. The equipment provides three basic levels of host control which determine the host's ability to control and monitor the equipment. The equipment operator sets the level of host control. Remote control capabilities permit the host to send commands like "START", "STOP", "PAUSE", "RESUME," and "ABORT" to control the equipment's processing.

Operation Notification

Collection events and alarms allow the host to monitor the interesting equipment operation. Equipment collection events notify the host of significant normal and abnormal activity. Equipment alarms notify the host when potentially dangerous activity is detected and cleared. The host determines which collection events and alarms are set up for notification. Certain events are required by the SECS/GEM connectivity standard, but the equipment is expected to define additional events to allow the host to monitor the equipment-specific activities.

LED lightbulb

Additional Resources