Issue link: https://iconnect007.uberflip.com/i/1213413
18 PCB007 MAGAZINE I FEBRUARY 2020 technology to include in their general equip- ment model (GEM-E30) protocol. As explained in the HP Journal article [6] : "SECS I incorporates the use of RS-232-C cabling and pin definitions and a relatively simple line protocol. SECS II defines larg- er messages (up to 4.3 Gb) to request and send status information, transfer recipe data, report alarm conditions, send remote equipment control commands, and handle material transfer. SECS I uses a simple ENQ- ACK handshake across an RS232-C line with checksums at the end of each mes- sage. SECS I also defines time-out intervals between handshake responses, individual message characters, and message respons- es. Message headers are defined in SECS I to include equipment identifiers, message identifiers, message block numbers, and other system information." "SECS II defines message types, format, content, and directions. SECS streams are groups of messages assigned to a gener- al set of equipment functionality. Within each stream, the individual messages are assigned function numbers. For example, SECS stream 1 function 5 (abbreviated S1 F5) is a formatted equipment status request, and stream 1 function 6 is the reply with the status information. Similarly, stream 7 function 5 is used to request the transfer of a process recipe, and stream 7 function 6 is used to transfer the recipe. SECS II also defines whether a reply is required or not, the message content and format (including data item definition headers), and whether a message may be used from equipment-to- host and/or host-to-equipment." The GEM/SECS-II standards are protocol independent. Today, there are two protocols defined by SEMI: SECS-I (E4) for serial com- munication and HSMS (E37) for network com- munication. Most systems today are using the HSMS standard. HSMS does not specify the physical layer. Any physical layer supported by TCP/IP can technically be used, but typically everyone just uses an Ethernet network inter- face controller (NIC) with an RJ45 port. A major advantage of the SECS standard is that it defines messages and their content; it defines how the messages are used together to perform a function. Equipment manufacturers are left to decide what messages to use to per- form functions that were performed manually before. The GEM standard is built on top of SEMI standard SECS-II (E5). The GEM standard has been adopted by oth- er industries, like the photovoltaic (solar cell) industry, and used by many in the electronics industry. It can serve as a model for the PCB fabrication industry by reviewing these SEMI standards: • SEMI E4: SEMI Equipment Communication Standard 1 Message Transfer (SECS-I) • SEMI E5: SEMI Equipment Communication Standard 2 Message Transfer (SECS-II) • SEMI E30: Generic Model for Communica tions and Control of Manufacturing Equipment (GEM) • SEMI E37: High-Speed SECS Message Service (HSMS) Generic Services • SEMI E81: Specification for CIM Framework Architecture • SEMI E96: Guide for CIM Framework Technical Architecture • SEMI E128: Specification for XML Message Structures MAPS Protocol: Message Automation and Protocol Simulation As explained in an overview tutorial by GL Communications Inc. [7]: "MAPS specifies a set of standard com- munication services for factory automation and has been accepted as an international standard by the ISO. It is a protocol simu- lation and conformance test tool that sup- ports a variety of protocols for such facto- ry floor controllers as PLC, robots, group controllers, and cluster controllers. MAPS is one of the oldest and most used of the factory floor automation protocols, being pioneered by General Motors and adopted by General Electric for its factories." "MAPS is based on the reference mod- el for open systems interconnection (OSI)