Industry News, Trends and Technology, and Standards Updates

What is GEM Control State?

The GEM Control State is one of the fundamental E30 GEM requirements. It defines the level of cooperation between the host and equipment and specifies how the operator may interact at the different levels of host control.

In a semiconductor factory, the host or operator may be in control of equipment processing. Having both sides in control of the equipment at the same time poses problems. When one side is in control of the equipment, the other side should be limited in the operations it can perform. For example, if an operator pauses processing, the host should not be allowed to send commands to resume processing or to start a new job. The GEM Control State is provided to prevent these types of issues from occurring.

Figure 1: SEMI E30 GEM Control State Model

How does the Control State work?

The Control State provides three basic levels of control. Each level describes which operations may be performed by the host and equipment sides.

Remote

• The host may control the equipment to the fullest extent possible.
• The equipment may impose limits on the local operator’s ability to control the equipment, but this is not a requirement of the standard. The host must be capable of handling unexpected commands invoked by the operator at the equipment.
• GEM Remote Commands are used by the host to invoke commands on the equipment.

Local

• The operator may control the equipment to the full extent possible.
• The host has full access to information. The host can collect data using other GEM features such as collection events, traces, and status data collection.
• Limits are placed on how the host can affect equipment operations:
  • Remote commands that initiate processing (e.g. START) or cause physical movement are prohibited. During processing, remote commands that affect processing (STOP, ABORT, PAUSE, RESUME) are also prohibited.
  • Other remote commands that do not initiate processing, cause physical movement, or affect processing may be allowed.
  • During processing, the host is prohibited from modifying any equipment constants that affect that process.
  • Equipment constants that do not affect the currently running process may be changed.
  • All equipment constants are changeable when not processing.

Offline

• The operator has complete control of the equipment.
• The host has no control over equipment operations and very limited information gathering capabilities.
• The only messages that the equipment will accept from the host are:
  • Messages used to establish GEM communication (S1F13/F14).
  • Requests to activate Online Control State (S1F17), but only if the currently active state is Host Offline (transition #11 on the Control State Model).
  • S1F2 “Are You There Response” while the attempting to go Online.
• The only primary messages that the equipment may send to the host are:
  • Messages used to establish communications (S1F13).
  • S9Fx messages, but only in response to the messages to which the equipment will normally respond to while Offline (i.e., S1F13 and S1F17).
  • S1F1 “Are You There Request” is sent to the host when the “Attempt ON-LINE” sub-state is entered. This message is used to get permission from the host to transition into an Online state (transition #5).
• No messages are spooled while Offline.

The Control State Model was designed in a way to give the equipment operator more control over the state machine than the host.  This protects the operator from unexpected state changes initiated from the host.

• The equipment operator can choose which Online sub-state is active through the operator interface. The host side cannot choose which Online sub-state is active.
• The equipment side can put the Control State Model into an Equipment Offline state (transition #6). When in this state, the host cannot request to go Online.
• The host side can put the Control State into a Host Offline state (transition #10), but the equipment side could reject this request. When in the Host Offline state, the equipment side can always attempt to go Online by first transitioning into the Equipment Offline state (transition #12) followed by an attempt to go Online (transition #3).

Operator Interface Requirements

The equipment must provide a way of displaying the current Control State to let the operator know who is in control of the equipment.

The equipment must provide a momentary switch to initiate the transition to the Equipment Offline state, and another switch to attempt to go Online from the Equipment Offline state. This may be a hardware switch on the front panel, but is often implemented in software using button controls.

The equipment must provide a discrete two-position switch which the operator may use to indicate the desired Online sub-state (Local or Remote). This may be a hardware switch on the front panel, but is often implemented in software using button controls. If implemented in software, the setting must be saved in non-volatile storage.

Conditional State Transitions

In the Control State Model, transitions #1, #2, #4, and #7 are conditional state transitions. The equipment application must provide a way of configuring which state to transition into. Equipment constants may be used for these configuration settings.

Conditional transitions #1 and #2 determine the initial state of the Control State Model during startup. The configuration that controls these transitions can be set for one of the following states:

• Online
• Equipment Offline
• Attempt Online
• Host Offline

Conditional transition #4 is used to determine which state to transition into after an equipment attempt to go Online fails. The configuration can be set to one of the following states:

• Equipment Offline
• Host Offline

Conditional transition #7 is used to determine which Online sub-state (Local or Remote) should be active when the Control State becomes Online. The configuration can be set to one of the following Online sub-states:

• Local
• Remote

Which Messages are used for Control State?

Click here to read the other articles in our SECS/GEM Features and Benefits series. 

To download a white paper with an introduction to SECS/GEM, Click below:

Even for someone who has been in this industry since the days of the TI Datamath 4-function calculator and the TMS1100 4-bit microcontroller (yes, that’s been a LONG time – the movie Grease premiered the same year!), it is sometimes hard to grasp the scope and complexity of what happens in today’s leading-edge semiconductor gigafabs. In fact, the only way to comprehend the enormous volume of transactions that occur is to consider what happens in a single minute – this is illustrated in the infographic we have labeled “The Gigafab Minute.”* 

In 1977, the classic movie "Close Encounters of the Third Kind" was released.  Towards the end of the movie, there is a dramatic "conversation" between the space aliens and the humans. One of the scientists makes the statement, "I hope someone is taking all this down."

What they really wanted was message logging!

Just like software logging is important for troubleshooting an application, logging the detailed message traffic between a factory host and the manufacturing equipment is just as important for troubleshooting.

For example, a host sends a command, and the equipment behaves based upon the message, but something does not work as expected.  It would be very helpful to see the message that was sent and the reply from the equipment, in conjunction with any other logs from the equipment to determine where the problem is located.

The format used to display/represent the logged messages is also very important. The latest industry standard for SECS message formatting is SEMI E173, the Specification for XML SECS-II Message Notation (SMN).

Here is an example:

<?xml version="1.0" encoding="utf-8"?>
<SECSMessageScenario xmlns="urn:semi-org:xsd.SMN">
                <Comment time="2018-02-05T18:19:20.365Z">State Change NotConnected</Comment>
                <Comment time="2018-02-05T18:19:20.400Z">State Change NotSelected</Comment>
                <HSMSMessage time="2018-02-05T18:19:20.394Z" sType="Select.req" direction="H to E" txid="1">
                                <Header>FFFF0000000100000001</Header>
                </HSMSMessage>
                <HSMSMessage time="2018-02-05T18:19:20.417Z" sType="Select.rsp" direction="E to H" txid="1">
                                <Header>FFFF0000000200000001</Header>
                                <Description>Communication Established</Description>
                </HSMSMessage>

Here is an S5,F5 example:

<SECSMessage s="5" f="5" direction="H to E" replyBit="true" txid="7" time="2018-02-05T18:19:20.507Z">
    <SECSData>
        <UI4 />
    </SECSData>
</SECSMessage>
<SECSMessage s="5" f="6" direction="E to H" replyBit="false" txid="7" time="2018-02-05T18:19:20.507Z">
    <SECSData>
        <LST>
            <LST>
                <BIN>0</BIN>
                <UI4>1</UI4>
                <ASC>Alarm 1 Text</ASC>
            </LST>
        </LST>
    </SECSData>
</SECSMessage> 

The SMN format is ideally suited for:

• Capturing the HSMS header information in a clear way
• Logging messages in an exact, binary format
• Reading the logs using software
• Creating a host or equipment emulator, since it is easy to read the logging from a software application and play it back.
• Extracting data from the SMN logs

The logs can be captured by the Equipment, Host, or even a "network sniffer" like Cimetrix's CIMSniffer utility.

Cimetrix’s Logviewer utility supports SMN logs as well:

With these standards and tools available, there's no reason to be like the scientist in Close Encounters, hoping that the messages were being logged.  Turn on logging!

Cimetrix's CIMConnect, HostConnect and SECSConnect all provide message logging in the SMN format.

Click here to read the other articles in our SECS/GEM Features and Benefits series. 

To download a white paper with an introduction to SECS/GEM, Click below:

SEMICON Taiwan was held September 5-7, 2018 at the Taipei Nangang Exhibition Center. During that same time (Friday September 7), the e-Manufacturing & Design Collaboration Symposium (eMDC) alsotook place in Hsinchu, Taiwan. Cimetrix exhibited in the Smart Manufacturing Pavilion and had a strong presence at both shows, exhibiting and speaking at SEMICON, and speaking and sponsoring a tea break at eMDC. 

Cimetrix SEMICON attendees included Dave Faulkner (VP Sales and Marketing), Michael Lee (Country Manager Taiwan), Yufeng Huang (Senior Software Engineer), Alan Weber (VP New Product Innovations), Samson Wang (Solutions Engineer) and Kimberly Daich (Marketing Manager); Hwal Song (Country Manager Korea) was also able to attend for one day. We were joined by several partners and distributors as well. The Cimetrix booth was busy throughout the show, and provided a comfortable and convenient setting for the many scheduled and walk-in meetings that took place.

In addition to the exhibitions, SEMICON Taiwan also sponsored many forums for expert speakers throughout the show. Dave Faulkner spoke on Friday morning on the topic of "Making Smart Manufacturing Work with EDA: The Stakeholder-driven requirements Development Process". On that same day, Alan Weber traveled to Hsinchu for eMDC and spoke on a similar topic, "Smart Manufacturing Stakeholders and Their Requirements." Smart Manufacturing is a prevailing topic across the industry and was featured at SEMICON Taiwan, as they continue the Smart Manufacturing Journey that began with SEMICON West. 

Our office in Taiwan has expanded recently with the addition of a new Solutions Engineer, and we are excited as new opportunities open up throughout the region. 

If you would like to learn more about Smart Manufacturing, our work in Taiwan or Cimetrix, please feel free to ask an expert any time. 

In the fourth article of this series, Fault Detection and Classification, we highlighted the application that has been the principal driver for the adoption of EDA (Equipment Data Acquisition) standards across the industry thus far, namely Fault Detection and Classification (FDC). In this posting, we’ll discuss another important application that effectively leverages the capabilities of the EDA standard: Fleet Matching and Management. 

Problem Statement

The problem that fleet matching (which also covers chamber and tool matching) addresses is maintaining large sets of similar equipment types at the same operating point in order to maximize lot scheduling flexibility by the real-time scheduling and dispatching systems that run modern wafer fabs. This avoids the situation where specific equipment instances are dedicated to (and therefore reserved for) critical layers of certain products, processes or recipes, which can reduce the effective capacity of the affected process area. This situation can arise because tools naturally “drift” apart over time, especially when manual adjustments are made to the equipment, or other factors (maintenance actions, consumable material changes, key sub-system replacements, etc.) affect the equipment’s operating envelope. 

Of course, part of the problem is choosing which equipment should be the one matched to—the so-called “golden tool.” And depending on the breadth of the fab’s product/process mix, there may be multiple targets to choose from, further complicating the task. 

Solution Components

The solutions for many of today’s complex manufacturing problems require lots of high-quality equipment data, and fleet matching is no exception. Like FDC, choosing the golden tool(s) also requires some information about which recent lots exhibited the highest yields, which must be correlated with the equipment used throughout the process. Unlike FDC, however, it is NOT necessary to build hundreds (if not thousands) of multivariate fault models specific to the various context combinations, because the underlying principle of chamber/tool/fleet matching is that “if all the fundamental operating mechanisms of a set of equipment are working consistently, then the behavior of the equipment in aggregate should likewise be consistent.” This means that the matching process can be largely recipe independent, which is a major simplification over other statistically based applications.

This is not as simple as it may first appear, because a complex equipment may have scores of these mechanisms (pressure/flow control, multi-zone temperature control, motion control, power/phase generation, etc.) for which thousands of parameters must be collected to characterize and monitor equipment behavior accurately. Static and dynamic equipment configuration information also comes into play, since similar (but not identical) tools may be interchangeable for certain processes. 

This is where the EDA standards enter the picture.

EDA Standards Leverage

Although not explicitly required by the SEMI EDA standards, the intent and expectation of its designers was to support a far richer (read “more detailed”) equipment metadata model than is practical in most SECS/GEM implementations. With respect to fleet matching and management, this would include not just the high-level status variables for key equipment mechanisms (listed above), but also the setpoints, internal control parameters, and detailed status of their underlying components. 

The metadata model must also include the complete set of equipment constants that govern tool operation, since these “constants” are sometimes changed “on the fly” by an operator within some allowable range. While this may be an acceptable production practice, it nevertheless affects the tool’s operating window, and must be accounted for in the matching algorithms. 

Moreover, the communications interface should support sampling and data collection of these detailed parameters at a frequency sufficient to observe the complete real-time operation of these mechanisms so the process and equipment engineers can more deeply understand how the equipment actually works. Support for this level of equipment visibility was also a stated requirement for the EDA standards.

Once this data is collected, a variety of analysis tools can look for similarities and anomalies in the equipment parameters to identify the factors that matter most in achieving consistent process performance. At this writing, a number of companies are looking at this domain as an ideal application for Artificial Intelligence and Machine Learning technology. Stay tuned for exciting developments in this area. 

KPIs Affected

The KPI (Key Performance Indicators) most impacted by the fleet matching and management application is overall factory cycle time, since the scheduling systems can make optimal use of all available equipment to move material through the fab.

Equipment uptime is also improved, because the continuous equipment mechanism “fingerprinting” process which is fundamental to fleet matching also catches potential problems before they cause the entire tool to fail. Finally, when more equipment instances are available for running experimental lots (rather than having dedicated tools for this), the yield ramp for new processes can be shortened as well.

If keeping a large set of supposedly identical equipment operating consistently is a challenge you currently face, give us a call. We can help you understand the approaches for building a standards-based Smart Manufacturing data collection infrastructure to support the machine learning algorithms that are increasingly prevalent in this latest generation of manufacturing applications… including fleet matching and management. 

To Learn more about the EDA/Interface A Standard for automation requirements, download the EDA/Interface A white paper today.

SEMICON Taiwan 2018 is just around the corner. Read the preview now in Chinese or below in English.

台灣半導體展在台灣微電子生產是一個非常重要的活動。矽美科即將在下週參加此半導體展。展期將由9/5 星期三至9/7星期五，在台北南港展覽館K2760 攤位。台灣半導體提供了一個很好的機會給公司及個人交流的平台，我們非常高興看到我們的客戶及新朋友分享我們的成長。

矽美科我們的 銷售和市場部副總裁 Dave Faulkner, 將會在9月7號禮拜五SEMICON TechXPOT演講。

若是你有經過我們的攤位K2760, 歡迎你跟我們的專家交流有關連線和相關的需求，我們會在現場做產品演練及介紹和告訴你們我們公司的簡介，你也可以預先來郵件預約，謝謝你。

SEMICON Taiwan is the premier event in Taiwan for microelectronics manufacturing and Cimetrix will be there next week! The show runs from Wednesday, September 5 through Friday, September 7, 2018 at the Taipei Nangang Exhibition Center. SEMICON Taiwan is always a great opportunity to connect with the companies and people in our industry and we are excited to see our clients, meet new people, and share the latest news of Cimetrix products and services with our Taiwan colleagues.

As the semiconductor and microelectronics manufacturing industries grow, SEMICON Taiwan continues to grow as well, both in the number of people who attend and in the number of exhibitors.   This year, Cimetrix will be exhibiting as part of the Smart Manufacturing & Automation Pavilion at Booth K2760. The Smart Manufacturing Pavilion is a great place to start to understand the entire manufacturing process including Front End, Back End and PCB Assembly. 

Cimetrix will also have an expert talk led by Dave Faulkner, Vice President Sales and Marketing, at the SEMICON TechXPOT on Friday, September 7, and we invite you to join us there.

On the same day, at the eMDC 2018 event in Hsinchu, our EDA expert, Alan Weber, will deliver a presentation titled Smart Manufacturing Stakeholders and Their Requirements.

Stop by our booth any time to talk to our experts about your specific connectivity and control needs. We will have onsite product demonstrations as well as information about our company available. You can also schedule in advance a time to meet with us at the show by filling out a quick form with your meeting request. 

Hwal Song of Cimetrix Korea talks about EDA/Interface A and Korean Equipment Makers. Read now in Korean or below in English.

Cimetrix Korea와 국내 파트너사인 링크제니시스는 EDA에 대한 세미나를 7 월 19 일에 개최했습니다. 삼성, SK 하이닉스를 포함한 글로벌 반도체 제조사들이 공정 장비의 추가 통신 프로토콜로 EDA를 채택함에 따라 EDA가 더욱 각광을 받게 되면서 개최한 세번째 세미나였습니다. 지금까지 200 명이 넘는 엔지니어가 이들 세미나에 참석하였으면, 이에 따라 한국에서의 EDA 연착륙이 진행 중입니다. 이들 세미나의 목적은 EDA의 이해부족로 오는 시행착오를 줄이고 첫번째 EDA구현을 가장 빠른 시간에 구현하기 위함입니다.

반도체 제조사의 EDA 채택은 차세대 분석 기능을 구현하고 딥러닝 및 머신 러닝 등과 같은 빅 데이터 및 AI의 새로운 기술을 수용하기 위한 주요 노력의 일환입니다. 대부분의 공정장비들이Freeze II 및 E164가 포함된 EDA 기능의 장착이 요구되거나 요구될 예정이여서,  Cimetrix Korea는EDA의 일반적인 개념뿐만 아니라 심도 있는 구현 방법론에 대한 이해를 위한 도움이 각 장비 제조사의 소프트웨어 엔지니어들에게 필요함을 인지하였습니다. 이러한 요구를 충족시키기 위해 다음과 같이 내용으로 세미나가 준비되었습니다.

• EDA관련 업계 동향 및 채택 현황 -  E164의 중요성 포함

• 반도체 제조사가 EDA 사양을 어떤 과정을 거쳐 준비하는가?

• 장비제조사의 소프트웨어팀 관점에서 EDA 구현의 모범 사례와 방법론

• 여러 장비제조사의 소프트웨어팀을 코칭한 컨설팅 및 지원 팀의 관점에서 EDA 구현 모범 사례와 방법론

• 구현중이거나 구현된 EDA 적합성 테스트의 모범 사례

활발한 토론과 Q&A를 통해서 한국의 장비 제조사들의 EDA에 대한 높은 관심을 엿볼 수있는 행사였습니다.

궁금한 점이 있으시면 언제든 연락주시기 바랍니다.

Cimetrix Korea and our local partner, Linkgenesis, held a seminar about SEMI EDA on July 19, the third one since 2016. EDA continues to gain momentum as global chip makers like Samsung and SK hynix have adopted EDA as an additional communication protocol for process tools. So far, over 200 engineers have attended these seminars, promoting the soft landing of EDA in Korea. Their goals include minimizing trial and error due to the lack of understanding on EDA, and speeding up the first deployment of EDA.

Adoption of EDA by chip makers is one of the major efforts for factories to implement their next-generation analytic capabilities and also embrace new technologies from big data and AI such as deep learning and machine learning. As most process tools are or will be required to ship with EDA capability, with Freeze II and E164, Cimetrix Korea recognized that Korean software engineers employed at equipment makers were looking for help in understanding in-depth deployment methodologies as well as understanding the general concept of EDA. In order to accommodate these needs, our seminars have been put together with following agenda:

• General industry trends of EDA and its adoption – the importance of E164
• How an EDA specification is put together by a chip maker
• Best practices & methodologies for implementation of EDA – from the perspective of a software team at a tool maker
• Best practices & methodologies for implementation of EDA – from the perspective of a consulting and support team who have coached many software teams in tool makers
• Testing best practices during and after EDA implementation

Active discussions and Q&A showed the high level of interest in EDA among Korean equipment makers. 

Please feel free to contact us whenever you have any questions.

Purpose of the Protocol Layer

The protocol layer packages data and reliably transfers it between the factory host and the equipment GEM interface.

Protocol Layer Definition

The protocol layer implements the transport technology and data packing algorithms used to send messages across a wire between a factory host and an equipment GEM interface.  

The SEMI E5 standard, SEMI Equipment Communications Standard 2 Message Content (SECS-II), defines  SECS messages that are used as the data and defines how they are packed into binary buffers for transport.

The SEMI E37 and E37.1 standards, High-Speed SECS Message Services (HSMS), define a protocol for exchanging SECS messages over a TCP/IP connection. This is the most used transport technology in SECS/GEM.

HSMS Protocol Stack

The SEMI E4 standard, SEMI Equipment Communications Standard 1 Message transfer (SECS-I), defines a mechanism for exchanging SECS messages over RS-232. This is normally used for older equipment or for some hardware inside an equipment such as an EFEM controller.

The rest of the document will focus on SECS messages over HSMS.

Protocol Layer Benefits

The protocol layer in GEM maintains the connection and detects a loss of connection so either party may take appropriate action such as activating Spooling. 

The protocol layer defines handshaking mechanisms to ensure delivery of messages if desired. 

The protocol layer connection is point-to-point between the factory host and equipment. It is a dedicated connection with no broadcast capabilities. This makes it easier to predict network loading.

Data Density

SECS/GEM transmits data with little overhead and high density. This means less network bandwidth usage for a given data set.  

For illustrative purposes, let us look at a typical example of an event report and compare SECS/GEM messaging to a somewhat equivalent XML and JSON message.

Take a typical GEM interface that uses unsigned 4-byte integers for IDs and an event report containing 8-byte floating point numbers and 4-byte integers. An example of this message is shown in the table below in a SECS/GEM format per E5 and in equivalent JSON and XML formats.

The binary SECS/GEM message will take 58 bytes over the wire, the JSON around 206 bytes and XML 175.  The JSON and XML numbers can change a bit based on key/element names and the above is just one of many possible representations.

A chart showing the data density comparison for the example message is shown below.  The Actual Data size is 2 4-byte integers + 2 8-byte floating point numbers + 1 4-byte event id + 1 4-byte report id = 32 bytes of actual data.  The overhead is calculated by subtracting the actual data size from the total number of bytes for the message.

For the example message the data density for SECS the data density percentages are shown in the graph below.  Data density percentage is calculated by the (actual data) / overhead *100.

Now if we change the example message to have 100 8-byte floating point numbers in it, the Data Density % graph changes to the chart below. Notice the JSON and XML are relatively the same, but the SECS/GEM data density increases to 78%.

SECS/GEM encoding has very little overhead.  The overhead for a message is 10 bytes for a header describing the message, plus 1 to 4 bytes for the size of the message body.  For any 4-byte integer or floating-point number in a SECS message, 6 bytes will be sent across the wire, 4 bytes for the integer value + 1 for the type + 1 for the length in bytes of the data.  Likewise, for any 8-byte integer or floating-point number, 10 bytes will be sent. For a string value, the length will be the number of characters plus 2 to 4 bytes. Any time a List (L in the readable example above) appears in a SECS message, 2 to 4 bytes will be added to the message.  

Arrays of numbers are brutally efficient in SECS/GEM. The overhead for an array is 1 byte for the type plus 1 to 4 bytes for the length of the array, plus the data in its native size. For example: an array of 10 4-byte integers would take 42 bytes, that is a data density of 95%! 

In the JSON example, a 4-byte integer requires 16 bytes + the number of characters needed to represent the integer, so 17 to 28 bytes. Floating point numbers are the same overhead, but probably requiring more characters to represent the value.

In XML, the overhead is based on the sizes of the XML element names.  Using the element names in the example above, for any 4 -byte integer the number of bytes across the wire will be 9 + number of characters needed to represent the integer, so 10 to 21 bytes. Floating point numbers are at the mercy of the string formatting used to represent the values. 

In summary, looking at the per-item byte size across the wire, SECS/GEM is very dense.  Take the 4-byte integer example where SECS/GEM is 6 bytes across the wire, the JSON example is 17 to 28 and the XML example is 10 to 21 bytes and you see as you scale the number of parameters the overhead really matters.  300mm Semiconductor equipment are expected to transfer 1000 parameters per second per process module to the host.  For a 2-module equipment, this results in the following number of bytes just for the data: 12K bytes/ over SECS/GEM, 34K-56K for JSON, and 20K-42K for the XML example. These numbers do not account for size of the rest of the message, just the actual parts related to parameter values. If that data is transferred in lots of messages with few values per message, then the network load is even worse. Fewer, larger messages are always better in all cases.

XML and JSON may also add to the overhead depending on the transmission protocol used.  For example, XML is often transmitted over HTTP using SOAP, this adds two additional layers of overhead and more bytes going across the wire for each message.The numbers of bytes shown for SECS/GEM are what is transmitted across the wire on top of TCP/IP. 

No Data Translation

Numeric data is transmitted with no translation in SECS/GEM.  Numbers are transmitted in their native format.  For example: an 8-byte floating point number is transmitted in its 8-byte representation without any conversion, truncation, or rounding. 

Any protocol such as JSON or XML must convert those 8-byte floating point numbers into a text representation.  This takes computing resources for the encoding and decoding and significantly more bytes across the wire. IEEE754 requires 17 decimal digits to accurately represent an 8-byte floating point number as a string. Adding in characters for sign, decimal point, exponent and exponent sign leads to 21 characters. That is over twice what SECS/GEM sends across the wire.

Circuit Assurance

HSMS defines a circuit assurance mechanism called Link Test.  The protocol layer has a timer that is started if there are no active message exchanges. Every time the timer expires, a protocol message is exchanged to ensure the connection is still open.  

Security

HSMS defines no security.  There is no validation of the connecting party, no credentials or certificate is required to connect. The data is not encrypted by any normal encryption algorithms; however, data is obfuscated through the data packaging process and is not generally human readable. 

Security is not normally seen as an issue since factory networks are isolated from the outside world.

Conclusion

The SECS/GEM Protocol Layer using HSMS provides a very efficient means of exchanging accurate data between the factory host and equipment. 

Click here to read the other articles in our SECS/GEM Features and Benefits series. 

To download a white paper with an introduction to SECS/GEM, Click below:

SEMICON West 2018 is fast approaching and the Cimetrix team is gearing up for a great show.  The show runs from July 10^th – 12^th at the Moscone Center in San Francisco and we’re looking forward to meeting with all our present and future clients.

This year SEMICON West is unveiling the new Smart Manufacturing Pavilion to showcase the entire manufacturing process from silicon to systems, including Front End, Back End and PCB Assembly. Cimetrix is excited to announce that we are a sponsor and will be participating in the Smart Manufacturing Pavilion showcase, both as part of the Front End segment as well as in the PCB Assembly area.

The Smart Manufacturing Pavilion includes a “Meet the Experts Theater” featuring presentations from two of our own Cimetrix thought leaders.  Alan Weber will present “Making Smart Manufacturing Work: The Stakeholder-driven Requirements Development Process” on Wednesday, July 11^th at 11:00 am. This process has already been used successfully to support the significant growth of SEMI EDA standards usage in Asia, but is equally relevant for a wide range of related Smart Manufacturing technologies.

Later on Wednesday afternoon at 3:00 pm, Ranjan Chatterjee and Dan Gamota of Jabil will present “Convergence of Technologies and Standards Across the Semiconductor, SMT and OSAT Segments.” 

Cimetrix will be exhibiting at booth #1122 in the South Hall, just a short walk from the Smart Manufacturing Pavilion. Stop by our booth or find us at the Pavilion to talk to our experts about your specific needs. We will have onsite product demonstrations as well as information about our company available.  You can also schedule in advance a time to meet with us at the show by filling out a quick form with your meeting request.  

See you at SEMICON!

Purpose of Spooling Messages

Even the most robust computer networks experience communication failure. Regardless of the cause, a small outage could be responsible for a significant amount of mission critical data loss. GEM mediates this loss of data by providing the message spooling capability.

Spooling Definition

“Spooling is a capability whereby the equipment can queue messages intended for the host during times of communication failure and subsequently deliver these messages when communication is restored" SEMI E30-0717 7.12.

Spooling Benefits

Automated factories are data-driven. Data is extracted and analyzed to make decisions that influence how engineering and management teams react to ensure product yield is high and scrap is low.

Gaps in this data could lead to erroneous judgement or even guessing. Spooling is a backup system that ensures this data will be preserved and restored reducing the risk of losing valuable data.

GEM Capability Requirements

Spooling is not a GEM requirement however, if this additional capability is implemented it must be done so properly. Here are a few requirements for implementing a compliant spooling interface.

The equipment must provide the host with the ability to enable and disable spooling via the equipment constant “EnableSpooling”. This EC is published by the equipment and the host can select the desired state.

When Spooling is implemented, it must be functional for all relevant primary messages and accessible using an S2, F43/F44 transaction. This excludes stream 1 messages which must be rejected if they attempt to “set spool”. 

Non-Volatile Storage

The equipment is responsible for allocating enough non-volatile-storage to store all messages that have been spooled for at least one processing cycle of the equipment. The NVS will also house all spooling-related status variables. NVS is used for this data so that if a power outage occurs the data is persisted.

Loss of Power

All messages that were spooled prior to the equipment’s power loss will be available since they are persisted in non-volatile storage. All spooling context is restored from NVS if spooling was active at the time of the power loss occurred. This includes the spooled data as well as all spooling related status variables persisted in NVS.

Host responsibility for implementation of Spooling

Message spooling requires hosts to participate to successfully recover after a loss of communication. It is Ideal to leave spooling in the disabled state until the host has been programmed to properly handle all conditions that may occur in the entirety of this state machine. Disabled spooling is better than improperly managed spooling. 

Once communication is re-established, the host must manage requesting the spooled messages. The host also has the option of purging the files from the equipment when necessary.

Conclusion

Though spooling is not a fundamental GEM requirement, if implemented it must be done so properly. Both host and equipment software have a responsibility to ensure GEM compliance when spooling is enabled. GEM spooling protects the potential loss of valuable data and provides a standard for both equipment and host software to adhere to with ease.

Click here to read the other articles in our SECS/GEM Features and Benefits series. 

To download a white paper on an introduction to SECS/GEM, Click below: