SECS/GEM Overview

SECS/GEM – Equipment-Host-Communication
 

The SECS/GEM standards lay the foundation for efficient equipment integration. 

1. The first layer is the communication protocol. While in former days, RS-232 communication (SEMI E4 – SECS-I) was sufficient, it is common practice today to use the faster TCP/IP connection (SEMI E37 – HSMS). This physical defines electrical and mechanical aspects of Ethernet communication, such as connectors or signal levels.
2. In the second layer SEMI E5 – SECS-II, structure and content of messages to be sent are described. These messages, called “Functions”, are grouped in “Streams” by their purpose (e.g. job management).
3. The third layer is the General Equipment Models (GEM). It provides the fab host with information of interest and describes expected equipment and host/MES behavior and capabilities (SEMI E30). This includes, e.g. remote control, publication of data, alarms and events, process program management (PPM) and state models. 

This enables fast integration and communication without equipment and host/MES knowing details about each other. A thorough documentation of the equipment’s SECS/GEM connectivity interface is mandatory. If the SECS/GEM standard set is sufficient, the equipment is typically loaded manually.

It is possible to use an equipment control that already has SECS/GEM communication capability or to equip an system with a SECS/GEM software solution such as FabLink®. FabLink® handles SEMI-compliant communication between a PC-based equipment control or a PLC system and the factory IT system. Various interfaces such as API, protocols and PLC-specific libraries are available for this purpose.

SECS/GEM Standards

• E4 – SECS I
• E5 – SECS II
• E30 – General Equipment Model (GEM)
• E37 – HSMS
• E167 - Specification for Equipment Saving Mode Communication (EESM)