一、概述
SECS/GEM是由国际半导体设备与材料协会（SEMI）制定的连接性标准。此连接性标准用于在设备和工厂的资讯和控制系统间建立通讯。SECS是SEMI设备通讯标准的缩写。GEM指SEMI连接性标准E30，被定义为制造设备实现通讯和控制的一般模型。一般来说，SECS/GEM标准定义了信息、状态机和情境，来让工厂软件能够控制并监视制造设备。正式名称是SEMI连接性标准E30。
在实现SECS/GEM标准的工厂内，存在主机和设备这两方。由设备在其中一台必须实施和遵守SEMI E30标准的计算机上运行软件。由制造商（工厂）运行与设备接口建立通讯的主机软件。主机无需遵守完整的连接性标准，因为它只设定设备的预期行为。不过，若要使用接口，主机必须进行主机端通讯。SECS/GEM为每条可能的主机信息设定了清晰的设备预期行为。
通讯
SECS/GEM SEMI连接性标准定义了主机和设备开始建立通讯的方式，并且还定义了当通讯中断时重新建立通讯的方式。在线识别方法负责验证设备的硬件和软件标识。终端服务功能允许主机操作员和设备操作员在控制台上交换手动输入的文本。
控制
SECS/GEM SEMI连接性标准概括了主机与设备操作员之间的合作等级的控制状态模型。设备提供三种基本的主机控制等级：离线，在线/本地，以及在线/远程，确定了主机控制和监控设备的能力。设备操作员设定主机控制的等级。远程控制功能允许主机发送诸如“启动”、“停止”、“暂停”、“继续”和“中断”这样的指令，用以控制设备的工作过程。
运作通知
收集事件和警报功能使主机能监控设备的运作情况。设备收集事件功能会将重要的正常活动和异常活动通知主机。当潜在的危险活动出现并随后被清除时，设备警报功能会通知主机。主机设定哪些收集事件和警报需要通知。SECS/GEM连接性标准要求特定的事件必须有通知，但一般会给设备定义额外的事件，以便主机监控具体设备相关的活动。
二、基本术语
| Term | Description |
|---|---|
| Alarm |
An alarm is related to any abnormal situation on the equipment that may endanger people, equipment, or material being processed" [SEMI E30, 2]. GEM allows the host to be notified when alarm conditions are detected and cleared. 设备处于非正常运行，可能危害操作员、设备或无聊的情况下，GEM允许当检测到告警或清除告警后通知host主机。 |
| Collection Event |
A collection event is a "detectable occurrence significant to the equipment" that "is considered to be significant to the host". [SEMI E30, 2] GEM allows the host to be notified when a collection event occurs. This allows the host to track the equipment's activity. 对于设备而言是可检测的事件信号。 |
| Data Variable |
Data variables "…may only be valid upon the occurrence of a particular event". [SEMI E5, 6.6]. The host can gather data variable values from the GEM Equipment. The data variable values provide information specifically related to the event. 针对某一特定事件才有效。主机能获取某一事件所有的数据变量值。 |
| Equipment Constant |
Equipment Constants are "settable by the Host"[SEMI E5 6.6]. The host can gather equipment constant values from the GEM Equipment. The host can also set equipment constant values on the GEM Equipment to control the equipment's behavior. 可被主机读取或设置的设备特性数据。 |
| GEM Equipment |
An "intelligent system which communicates with a host" [SEMI E4, 2.1] and complies to the SECS/GEM standard. 就是一个遵循SECS/GEM协议标准，并能与主机进行通信的设备系统。 |
| Host |
"An intelligent system which communicates with the equipment." [SEMI E4, 2.1]. The host can be viewed as a line management system. GEM does not intend to define how the host should behave. The GEM SECS standard defines the set of messages a host must use when interacting with GEM Equipment. A GEM Equipment can communicate with one host. A host can communicate with multiple GEM Equipment. 就是一个线性控制系统（系统当然包含了依附在硬件上的软件） |
| HSMS-SS |
SEMI standard High Speed Message Service-Single Session which defines TCP/IP network communication used by SECS/GEM for host/equipment communication. It is replacing the SECS-I standard. Only one client host can use a specific port at a time. 在SECS/GEM标准中通过定义TCP/IP网络通信协议在单客户端-主机的情况下使用指定端口下可替换SECS-1。 |
| PV2 | GUIDE FOR PV EQUIPMENT COMMUNICATION INTERFACES (PVECI), based on SECS/GEM, specifically for photovoltaic equipment suppliers. |
| Process Program | A Recipe (see Recipe) |
| Recipe | A set of instructions for the equipment. |
| Report |
"A set of variables predefined by the equipment or defined by the host…". The host uses reports to gather status variable, data variable, and equipment constant values. The host can request a report explicitly or attach a set of reports to a collection event. 就是应答。 |
| Status Variable |
"Status variables may include any parameters that can be sampled in time such as temperature or quantity of a consumable（消耗品数量）." [SEMI E5, 6.5] "Status values … always contain valid information." [SEMI E5, 6.6]. The host can gather status variable values from the GEM Equipment. 状态变量/数据 |
| SECS-I |
SEMI Equipment Communications Standard 1 Message Transfer - defines RS-232 serial communication used by SECS/GEM for host/equipment communication. It is phasing out due to inherent speed limitations. It is being replaced by the HSMS standard. 现阶段由于自身速度的限制，已逐步被HSMS标准替代。 |
| SECS-II | SEMI Equipment Communications Standard 2 Message Content. SECS GEM is a specific implementation of the SECS-II standard. SECS-II defines most concepts and functionality used in the SECS/GEM standard. Many SECS-II capable systems are not GEM compliant. |
| SECS-II Message | All GEM Equipment and host communication is accomplished using SECS-II messages. Each unique SECS-II message is identified by its stream number (S) and function number (F). The SECS-II standard defines a large set of SECS-II messages determining each one's purpose, content, and usage. The SECS GEM standard defines how to use a subset of these SECS-II messages yet allows other SECS-II messages to be used in addition to this subset. To learn more about SECS Messaging, download the primer. |
