Design and Performance Analysis of a Non-Standard EPICS Fast Controller J
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1 Design and Performance Analysis of a Non-Standard EPICS Fast Controller J. Jugo Member, IEEE, M. Eguiraun, I. Badillo, I. Arredondo, D. Piso Member, IEEE. Abstract—The large scientific projects present new techno- systems for scientific facilities, [2]. In particular, it is useful for logical challenges, such as the distributed control over a com- the connection of large number of controllers in a networked munication network. In particular, the middleware EPICS is environment and gives monitorization, supervision and control the most extended communication standard in particle accel- erators. The integration of modern control architectures in these utilities, including feedback actions and guaranteeing soft real- EPICS networks is becoming common, as for example for the time behavior. PXI/PXIe and xTCA hardware alternatives. In this work, a The evolution of EPICS over the years in different facilities different integration procedure for PXIe real time controllers reflects its capabilities in these environments. EPICS has been from National Instruments is proposed, using LabVIEW as the evolved and adopted in a large number of facilities due to its design tool. This methodology is considered and its performance is analyzed by means of a set of laboratory experiments. This power and versatility and, nowadays, it is used in many particle control architecture is proposed for achieving the implementation accelerators and other large facilities, including telescopes, and requirements of the fast controllers, which need an important other scientific and industrial facilities, [3], [4], [5]. Some amount of computational power and signal processing capability, of the well known facilities using EPICS are the Spallation with a tight real-time demand. The present work studies the Neutron Source in USA [6] , the KEKB Collider in Japan, [7] advantages and drawbacks of this methodology and presents its comprehensive evaluation by means of a laboratory test and the Diamond Light Source in United Kingdom, [3]. bench, designed for the application of systematic tests. These tests Recently, EPICS has been chosen as the key element in compare the proposed fast controller performance with a similar the control system for the International Thermonuclear Ex- system implemented using an standard EPICS IOC provided by perimental Reactor (ITER), being the heart of the CODAC the CODAC system. (Control, Data Access and Communication) system, [8], [9]. In Index Terms—EPICS middleware, fast controller, PXI/PXIe, addition to this relevant international center, the international LabVIEW. project IFMIF/EVEDA, [10] and the European Spallation Source (ESS AB), have chosen EPICS as their respective I. INTRODUCTION control system [11], [12]. On the other hand, different hardware solutions are used The particle accelerators require a high variety of technolo- under EPICS for the development of the control systems and gies for a correct operation, both cutting-edge and mature. the related diagnostics. In this regard, it is worth stressing Therefore, an important effort must be focused on the develop- that one of the most relevant characteristics required in those ment of new technologies in order to achieve the high demands applications is the high reliability and long lifetime of the in this field. The control tasks in a large scientific facility are selected technology, since the accelerators are designed for an fundamental for a correct machine operation and for ensuring operation of decades. For this reason, the technology involved the safety of the machine and the personal. The design of in the implementation of any particle accelerator must be those control systems is a challenging problem, which must well known and therefore, has been used along decades. take into account considerations about the distributed nature arXiv:1406.3954v1 [cs.SY] 16 Jun 2014 Highlighted examples are hardware elements based on the of the facility and the variety of present technologies. standards CAMAC [13], and VME [14]. Experimental Physics and Industrial Control System In particular, control devices based on VME have been (EPICS) middleware is one of the most relevant solutions a very relevant elements in the last years, [15]. Therefore, developed for the implementation of the control solutions in EPICS has a wide support for hardware based in this standard. this class of facilities and, in particular, it is very usual as main However, the technological advance for instrumentation and control technology in particle accelerators. This open source control has lead to the appearance of new standards such as toolkit was initially developed for the control system of the PXI/PXIe and more recently, xTCA [16]. Hence, following Advanced Photon Source (APS) in the Argonne National Lab- those advances different initiatives are trying to increment oratory in collaboration with the Los Alamos National Labo- the support for this kind of technologies and its integration , ratory, [1] and is a software framework specifically designed in EPICS. In fact, the efforts for integrating PXI/PXIe based for the development and implementation of distributed control hardware in EPICS networks is being positively fueled by the J. Jugo, M. Eguiraun and I. Badillo are with the Department of Electricity impulse received in the last years. and Electronics, University of the Basque Country, Leioa, 48940, Bizkaia, In this sense, the development of standardized solutions for SPAIN, e-mail: [email protected]. the ITER project using PXI/PXIe platforms is a remarkable I. Arredondo is ESS Bilbao, Edificio Cosimet Paseo de Landabarri 2, 48940, Leioa (Bizkaia), Spain. fact. The CODAC distribution includes the device and driver D. Piso is with ESS-AB, Lund, Sweden. support for PXI/PXIe based hardware, in order to develop 2 standard EPICS IOCs, [9]. In particular, there is an strong oped using the tools provided by the CODAC distribution. This interest for providing support for the National Instruments comparison is based on a test bench which simulates a real devices which include FPGA cards for data acquisition and control system environment, following the scheme proposed in control applications. The deployment of the integration of a [22]. This system emulates real schemes present in scientific standard EPICS IOC for a NI PXI/PXIe based controller is facilities and in particular, a particle accelerator. A large described in [17]. An additional proposal in [17], similar to number of process variables are considered, including digital the one presented in the work, is based on the implementation and analog IO signals, monitors and data processing. The work of an EPICS server in a PXI/PXIe controller under LabVIEW describes the implementation of the test bench and analyzes RT. Finally, the use of a LabVIEW based EPICS CA server, the results comparing both architectures. The study is focused which is still under development, is proposed in [18]. on the reliability of the configuration, facing the proposed solution and the EPICS standard methodology. The main objective of this work is the description of an This work is organized as follows. First, the motivation of architecture appropriate for the integration of NI PXI/PXIe this work is presented in Section 2. Next, Section III describes platforms in EPICS networks, extending and complementing the main characteristics of the proposed architecture for PXI the results presented in [19]. The use of this hardware is based fast controllers and its integration in EPICS networks. In oriented to the implementation of the so called fast controllers, Section IV, the laboratory test bench implemented for testing [20], which in the current case are based on the use of FPGA the proposed solution and the obtained results are presented. cards and real time controllers. The graphical design tool Lab- Finally, the conclusions and future work end this paper. VIEW is used as the development tool for the development of the control application. This architecture has been successfully applied in a real system, specifically in the control system for II. RELIABILITY OF COTS CONTROL SYSTEMS FOR the ISHN ion source developed in ESS Bilbao, [19] as well PARTICLE ACCELERATORS as in [21]. The control system of a particle accelerator must fulfill In addition to the details of the proposed architecture and multiple technological challenges, therefore an efficient design its implementation, a test bench developed for the validation architecture for the control system must be considered, taking of the proposal is presented. The results obtained from the into account all of the requirements for the whole facility. preliminary tests are also described. Moreover, several labo- In particular, some applications needs stringent requirements: ratory tests have been designed and implemented in order to a fast response, precise real-time measurements, fast data compare the reliability of the proposed system and compare to acquisition, etc. In those cases, an advanced hardware is a similar hardware which implements a standard EPICS IOC, needed to cope with the requirements, and to get the so called based on the support provided by CODAC. The initial results fast controller, a high performance controller. In order to get show that both systems provide a comparable performance. the required characteristics, the use of the most advanced and In this case, the controller is implemented using LabVIEW- commercial available control hardware is a valuable choice, RT and its integration in EPICS networks is based on the use taking into account the associated costs. In fact, the usage of of the LabVIEW EPICS server by means of the Data logging COTS hardware usually requires a lower cost than home-made and Supervisory Control module (DSC), with an additional ad hoc designs, which involves a time and budget consuming interface to EPICS by means of a new external IOC. The design and development process. resulting system is equivalent to a standard EPICS IOC, An architecture which is gaining relevance in modern ac- overcoming the limitations present in the LabVIEW EPICS celerators is the use of control chassis based on PXI/PXIe server. This approach has several advantages derived from platforms.