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内容記述 |
This thesis is on investigation and implementation of embedded EPICS<br />controllers by the use of micro-ITRON to overcome many disadvantages caused by<br />the advent of Ethernet-based device controllers. <br /><br /> At present almost all accelerator control systems are kind of DCS (Distributed<br />Control Systems) on the basis of so called the standard model. In the standard model,<br />the control system consists of three layers: the presentation layer, the device control<br />layer and the interface layer. <br /><br /> Another trend of accelerator control systems at present is to use a free toolkit for<br />its middle-ware. Among a few toolkits, EPICS (Experimental Physics and Industrial<br />Control System) is the most widely used. EPICS was first developed in 1991.<br />EPICS’s open, free and full DCS-based features have made it to be adopted in many<br />control systems of scientific facilities, such as accelerators, telescopes, and large<br />high-energy experiments. <br /><br /> EPICS is designed on the basis of the standard model. The first two layers,<br />namely, the presentation layer and the device control layer, are divided functionally,<br />but connected with each other through a high-speed network such as FDDI. The<br />presentation layer which is called OPI (Operator Interface) layer in the EPICS<br />terminology is typically composed of several workstations and X-terminals that are<br />used as operator consoles. The device control layer consists of VME IOCs<br />(Input/Output Controller) and/or other kinds of computers to accomplish the data<br />processing and control logic. The interface layer is composed of I/O modules on IOC<br />or other field bus modules that interface devices.<br /><br /> Recent rapid development of Ethernet has made it de fact international standard<br />as the network in accelerator control systems. More and more device controllers with<br />Ethernet interface have been widely used, such as PLCs (Programmable Logic<br />Controller), to replace old field bus interface device controllers. These Ethernet-based <br />device controllers are equipped with more CPU power and memory capacity, and<br />have become intelligent enough to process the control logic that was originally<br />accomplished by IOCs. <br /><br /> Now due to the advent of Ethernet-based device controllers, the standard EPICS<br />3-Layer model becomes redundant and show some disadvantages: <br /><br /> ・ Lacking of real-time response: IOCs communicates with intelligent device<br /> controllers through Ethernet, while, Ethernet, as defined in IEEE 802.3, is<br /> unsuitable for strict real-time industrial applications because its<br /> communication is non-deterministic. <br /> ・ Ineffective use of hardware: in EPICS, when we use intelligent device<br /> controllers, a complicated device driver called “asynchronous driver” is put<br /> on IOCs to drive intelligent device controllers. Expensive VME machine are<br /> only used as “protocol transformer” that translates the manufacture’s<br /> proprietary protocol to EPICS CA (Channel Access) protocol. <br /> ・ Duplication of programs: we have put runtime database on IOCs and also<br /> similar programs at intelligent device controllers such as Ladder on PLCs. <br /><br /> One way to avoid these disadvantages and maximally use the benefit of using<br />intelligent device controllers is to implement integrating control software (IOC core<br />program named as iocCore in EPICS) on these intelligent device controllers, thus<br />making existed intelligent device controllers to work as separated IOCs. We call this<br />type of controller embedded EPICS controller.<br /><br /> From EPICS base 3.14.x, iocCore supports can run not only on VxWorks but also<br />recent versions of RTEMS, Solaris, Linux, HPUX, Darwin and Windows, and there<br />have been some implementations of embedded EPICS controllers running on<br />VxWorks and Linux. But they all have some shortages. For example, embedded<br />EPICS controller running on Linux does not have any good real-time response, and <br />embedded EPICS controller running on VxWorks lacks BSP (Board Support Package)<br />support from the hardware manufacturer. <br /><br /> Many intelligent device controllers available on the market in Japan use<br />micro-ITRON, a kind of Japanese domestic real-time kernel. The advantage of<br />micro-ITRON is that these intelligent device controllers have BSP for micro-ITRON.<br />We have investigated the use of micro-ITRON as a kernel on Ethernet-based device<br /> controllers and also implemented embedded EPICS Controllers on micro-ITRON.<br /><br /> After implementing embedded EPICS Controllers running on micro-ITRON, the<br />redundant device control layer can be omitted. EPICS architecture can be recovered<br />back to the standard 3-Layer model and the disadvantages mentioned before can be<br />eliminated. Also running iocCore on micro-ITRON allows us to apply embedded<br />EPICS concept to smaller devices that could not be supported by previous solution. <br /><br />This thesis also discusses the performance of the embedded EPICS Controllers<br />and shows that it can be used for real applications. |
要旨・審査要旨 (255.1 kB)
