eScada implements the SEMI SECS/GEM standards natively, without any third party library: a dedicated derived object exposes the HMI solution as a GEM Equipment towards the factory host (MES, cell controller) over HSMS-SS on TCP/IP, with SECS-II messaging according to SEMI E5, E30, E37 and E37.1.
The host can read Status Variables, read and write Equipment Constants, receive Collection Events and Alarms, sample variables over time through trace data collection, send Remote Commands, exchange operator messages through the terminal services and manage recipe files as Process Programs. Every GEM object is mapped on a tag of the project, so the data already used by the HMI pages and by the project logic becomes visible to the host without duplications.
The set of exposed objects, the equipment identity (MDLN, SOFTREV), the protocol timers (T3, T5, T6, T7, T8) and the connection parameters are declared in an XML configuration file. The same file can be shared by several instances, each running in its own thread, overriding endpoint and device ID per instance. The control state (offline, online local, online remote) stays in the hands of the operator through a tag, as the standard requires, and the object reports link state, communication state and message counters as diagnostic items.
Nearly all the GEM capabilities defined by SEMI E30 are implemented, including establish communications, dynamic event report configuration, variable and trace data collection, alarm management, remote control, equipment constants and clock; the implementation has been validated on the field on a production line. Spooling is not supported and is declared as such, following the GEM procedure.
SECS/GEM makes the HMI solution ready for the semiconductor, photovoltaic and electronics industries, where the factory host expects every piece of equipment to speak GEM. The SEMI standards are the authoritative reference and are available at www.semi.org.