【正文】 onfigured destinations like alarmfiles, (printer) queues or displays. SCADA Systems with DCS Features (Cube) The fact that the D/3 system mentioned above had some hard coded limitations with respect to the Y2K problem was forcing us to look for an upgrade or a replacement of the existing system. As a result of a call for tender the pany Orsi with their product Cube came into play [2]. The project included a plete replacement of the installed functionality. This included the D/3 as well as the integration of the DESY field bus SEDAC and the temperature conversion in VME. The project started promising. But soon technical and anizational problems were pushing the schedule to it?s limits which were determined by the HERA shutdown scheduled at that time. The final acceptance test at the vendors site showed dramatic performance problems. Two factors could be identified as the cause of these problems. The first one was related to the under estimated CPU load of the 6th grade polynomial temperature conversion running at 1 Hz. The second one was the additional CPU load caused by the plex functionality of the existing D/3 system. Here it was underestimated that each digital and analog input and output channel had it?s own alarm limits in the D/3 system. In a SCADA like system as Cube the base functionality of a channel is to read the value and make it available to the system. Any additional functionality must be added. Last not least the load on the work for polling all the alarm limits – typically for a SCADA system – was also driving the work to it?s limits. Finally the contract with Orsi was cancelled and an upgrade of the D/3 system was the only possible solution. It was finally carried out in march 2021. In any case it should be mentioned that the Cube approach had the advantage of a homogeneous configuration environment (for the Cube front end controllers) – pared with heterogeneous environments for ?pure? SCADA systems. SCADA (PVSSII) The H1 experiment at the HERA accelerator decided to use PVSSII for an upgrade of their slow control systems[3]. The existing systems were developed by several members of the H1 collaboration and were difficult to maintain. The decision to use PVSS as a replacement was driven by the results of an extensive survey carried out at CERN by the Joint Controls Project [4]. PVSS is a ?pure? Supervisory And Data Acquisition System (SCADA). It provides a set of drivers for several field buses and generic socket libraries to implement munication over TCP/IP. The core element is the so called event manager. It collects the data (mostly by polling) from the I/O devices and provides an event service to the attached management services like: control manager, database manager, user interface, API manager and the built in HTTP server. The PVSS scripting library allows to implement plex sequences as well as plex graphics. Compared with other SCADA systems PVSS es with one basic feature: it provides a true object oriented API to the device?s data. One major disadvantage of SCADA systems is the fact that two databases, the one for the PLC and the one for the SCADA system must be maintained. Integrated environments try to overe this restriction. EPICS EPICS has emerged at DESY from a problem solver to a fully integrated control system. Starting from the data collector and number cruncher for the cryogenic control system, EPICS made it?s way to bee the core application for the DESY utility group. In addition it is used wherever data is available through VME boards or by means of Industry Pack (IP) modules. For those cryogenic systems which are not controlled by the D/3 system EPICS is used with it?s plete functionality. In total about 50 Input Output Controller (IOC) are operational processing about 25 thousand records. 1 EPICS as a SCADA System The utility group ( water, electrical power, pressed air, heating and air conditioning) is using a variety of PLC?s spread out over the whole DESY site. EPICS is used to collect the data from these PLC?s over Profibus (FMS and DP) and over Ether (Siemens H1 and TCP). The IOC?s provide the interfaces to the buses and collect the data. The built in alarm checking of the EPICS records is used to store and forward alarm states to the alarm handler (alh) of the EPICS toolkit. In addition tools like the channel archiver and the graphic display (dm2k) are used. The default name resolution (by UDP broadcast) and the directory server (name server) are used to connect client and server applications over TCP. All of these are basically SCADA functions. The textual representation of all configuration files ( for the IOC, the graphic tool, the alarm handler and the archiver) provides a flexible configuration scheme. At DESY the utility group has developed a set of tools to create IOC databases and alarm configuration files from Oracle. This way the controls group provides the service to maintain the EPICS tools and the IOC?s while the users can concentrate on the equipment being controlled. 2 EPICS as a DCS System Besides the basic ponents of a SCADA system EPICS also provides a full flavoured Input Output Controller (IOC). The IOC provides all of the function a DCS system requires, such as: a standard set of properties implemented in each record, built in alarm checking processed during the execution of each record。工業(yè)控制要求可靠性，完整的文獻(xiàn)記載和技術(shù)支持。而且軟件無法在 秒的穩(wěn)定重復(fù)率下運(yùn)行 PID 控制回路。因?yàn)榧⒖刂葡到y(tǒng)（ D/ 3）的特性，所以這決定很不錯(cuò)。該項(xiàng)目很有前景。最后，所有網(wǎng)絡(luò)負(fù)載的報(bào)警限值，尤其是 SCADA系統(tǒng)，也促使網(wǎng)絡(luò)生成了限制。 PVSS 是一個(gè)“純粹”的監(jiān)控和數(shù)據(jù)采集系統(tǒng)（ SCADA 系統(tǒng)）。 EPICS： 在德國(guó)電子同步加速器研究所， EPICS 從問題解決系統(tǒng)演化成了全集成控制系統(tǒng)。默認(rèn)名決議和目錄服務(wù)器（域名服務(wù)器）用于連接 在 TCP 客戶端和服務(wù)器應(yīng)用程序。靈活的數(shù)據(jù)采集模式，支持調(diào)查模式以及發(fā)布訂閱模式。 功能 持續(xù)不斷的問題，如為什么控制系統(tǒng)的加速器和其他高度專業(yè)化的設(shè)備聯(lián) 合協(xié)同發(fā)展。 I / O 和控制回路 復(fù)雜的控制算法和控制回路和域名 DCS 控制系統(tǒng)一樣。 硬件支持 對(duì)現(xiàn)場(chǎng)總線和起源于 I / O 的 Ether 的支持是為 SCADA 系統(tǒng)服務(wù)的一個(gè)基本功能。基于控制系統(tǒng)的 UNIX 很難互相連