SECS/GEM Frequently Asked Questions

Where can I get a copy of the SECS/GEM standard? Official copies must be obtained through SEMI. SEMI offers excellent internet services at their website. Standard documents can be ordered or downloaded for a fee at the SEMI website
How does a system become GEM certified? There is no official SECS GEM certification. GEM compliance is self-proclaimed, but GEM equipment can be tested for compliance using Cimetrix EquipmentTest™. Note that GEM compliance does not require all GEM/ SECS features to be implemented. For example, some equipment do not implement remote commands and process program management yet they can still be GEM compliant if they correctly implement the GEM Fundamental Capabilities.
Can more than one host establish communication with an equipment at one time? Not in many GEM interfaces. However, the Cimetrix CIMConnect software product has a built-in multiple client (multi-host) feature that inherently makes it trivial to communicate with more than one SECS/GEM host at a time using HSMS-SS or SECS-I communication. When using HSMS-SS, each client uses a unique port.
How long does it take to implement a GEM SECS interface? CIMConnect
How fast is a GEM/SECS interface? Current versions of the SECS GEM standard allow the host to set up trace data collection with the message rate specified in milliseconds. In practice, some factories request data at rates of about 10Hz, or 1 set of data every 100ms. Because the SECS-II and HSMS message format is very efficient, a lot of data can be transferred using little network bandwidth. The precise data rates depend on many factors such as the network, the GEM software in both the host and equipment systems and the computer hardware. Older versions of the SECS/GEM standard were limited to 1 Hz trace data collection.
What features in a SECS/GEM product are important? There are many important features, but here are some of the key ones:
  • Customer Support
    The GEM interface can be a production-critical feature. There are many details in the GEM SEMI standards that take years to master. Before selecting a product, make sure that the product is backed by a solid company with a responsive, experienced customer support team.
  • Performance
    Some products use much less CPU than others for the same set of tasks. A product that uses less CPU can achieve higher data collection requirements. As factories attempt manufacturing process optimization, they rely on more and more data collection from the equipment. Select a product that can use computer resources most efficiently and can meet both today's and tomorrow's throughput requirements.
  • Multiple Client Support
    In recent years, the importance for supporting multiple clients has increased. For example, PV manufacturers documented the need for an "IT interface of the equipment that allows an arbitrary number of clients to connect to the equipment in order to gather data from the equipment (all kinds of data collection) and to interact with the equipment (remote control, etc)". Choose a product that has multiple client access as a built-in feature such as CIMConnect.
  • Client Server Architecture
    A GEM interface interacts with all of the components within the equipment. Purchase a product with a client-server architecture so that all of the components can interact directly with the SECS GEM software. This saves on software development.
Can changes be made to the SECS/GEM standard? The SECS/GEM standard is an active SEMI standard managed by the GEM 300 task force. Periodically changes to the GEM SECS standard are submitted for discussion and for ballot approval. Changes must be approved according to SEMI's standard processes. Anyone can join the GEM 300 task force, vote on the changes to the standard, and submit recommendations. More information is available from the following websites:
Where can I ask questions about the SECS/GEM standard? You are welcome to emails questions to
How much network bandwidth does a GEM interface require? While the equipment determines how much information is available to the host, ultimately the host determines the bandwidth utilization by enabling the desired collection events and alarms and by disabling the undesired ones. The host also determines the amount and frequency of data gathering, recipe management, remote commands, and other features. If all of the events and alarms are disabled, then a GEM interface connection will be nearly silent.