NAKAMOTO Eiji1 OKADA Satoshi1
We have developed two models of autonomous controllers as the core of the STARDOM network-based manufacturing solution: the FCN (acronym for field control node) is a modulus controller with superb scalability and the FCJ (acronym for field control junction) is an all-in-one controller designed for distributed in-situ installation. Both controllers incorporate "open" and standardized technologies and feature functions to implement control logic compliant with IEC61131-3 standard of the International Electrotechnical Commission and Web-based communication functions such as autonomous e-mail transmission and communication with Web pages, all in a compact, rugged body. These features realize full-scale, practical use of the up-to-date network technologies, a highly reliable architecture for stable operation, and increased engineering efficiency with the flexibility to address system changes.
We have developed the FCN (field control node) and FCJ (field control junction) autonomous controllers as the core of STARDOM, a solution that actualizes a network-based control system (NCS) Yokogawa proposes for increased production efficiency. In addition to conventional combined functions such as regulatory control and sequence control, the FCN and FCJ feature a highly independent architecture for linking up distributed controllers and devices via a network to integrate the control domain and autonomously transmitting information. The design oriented for distributed installation, centralized control information within each of the FCN and FCJ controllers, and highly reliable architecture allowing duplex configurations assure steady operations, and the standardized engineering methods (conforming to IEC61131-3) make engineering more efficient, from purchase to operation and on to expansion and modification.
This paper introduces the hardware and software features of the FCN and FCJ.
Figure 1 Example of System Configurations
The exceptional, independent nature of the architecture allows the FCN and FCJ autonomous controllers to accommodate diverse styles of system configurations such as standalone control, interlinking control of multiple controllers connected by a control LAN, and interlinking control with data server software. Figure 1 illustrates an example of system configurations. 100- Mbps Ethernet is used as the control LAN to link various controllers and devices, and the control LAN between the autonomous controllers and VDS (Versatile Data Server Software) can be duplexed for higher reliability.
Controller hardware is offered in two models: FCN, a modulus controller with outstanding scalability, and FCJ, an all-in-one controller designed for in-situ installation. The FCN is applicable to a mission-critical system because its components can be made duplex.
In terms of software, a control (loop control and sequence control) implementation environment and Java virtual machine for running Java applications are incorporated to carry out autonomous information transmission by e-mail or to Web pages. FCN and FCJ controller applications are written in programming languages compliant with the IEC61131-3 international standard, and users can choose the most suitable language for each application or the preference of the users from five IEC61131-3-compliant languages. The adoption of IEC61131-3-compliant languages enable standardized engineering and reuse of the engineering results, thus simplifying the engineering. These development environment and modification and setting tools run on a generic personal computer.
As aforementioned, autonomous controllers are offered in two models, the modulus FCN and the all-in-one FCJ; nonetheless, they have the same hardware architecture. The following describes the features and specifications of each model.
The modulus FCN consists of a power supply, CPU, various I/O, and base modules. All key parts can be duplexed, and the excellent scalability means it is adaptable to small- to medium- scale systems. As shown in Figure 1, up to two I/O extension units can be connected to each FCN to install up to 25 I/O modules with the standard configuration, or up to 20 I/O modules with the fully duplexed configuration.
The CPU module is based on a PC/AT-compatible architecture as a result of placing a premium on openness to attain autonomy. This facilitated incorporation of "open" software components including a general-purpose realtime operating system, control implementation environment, and Java virtual machine.
To increase reliability, ECC (error checking and correcting) memory is used for both the main memory and storage memory, and error detection functions such as the self-diagnostics, watchdog timer, and bus parity check as well as reliability, availability, and serviceability (RAS) are enriched. The module itself is devised to run on low power, and a fan-less, natural air- cooling design is employed, allowing high maintainability.
The power supply and CPU modules as well as the control LAN and internal bus connecting I/O expansion units can be duplexed individually, and modules are hot-swappable. When duplexed, a pair of CPUs run synchronously, so the continuity of control is maintained even in the event a switchover of the control right and thus the user need not care about special programming for a duplication when developing controller applications.
|Figure 2 Appearances of FCJ|
The FCJ is an all-in-one controller designed for distributed installation on site and has a limited number of analog and digital inputs and outputs because its main objective is forming links to field networks (see Figure 2). To be suitable for installation inside a local panel, the FCJ is made compact and slim and is equipped with a terminal block for signal connections. It is driven by a single 24 V DC power supply. There is no difference in the internal architecture from the FCN, namely, the FCJ has ECC memory, a temperature monitor and all the other aforesaid features. However, about redundancy, the control LAN can be duplexed but the power supply and CPU modules cannot.
As the I/O, the FCJ has six 1 to 5 V DC analog inputs, two 4 to 20 mA DC analog outputs, sixteen 24 V DC digital inputs, sixteen 24 V DC digital outputs, and two RS-232C serial interface ports, and will soon have two H1 FOUNDATION Fieldbus ports (under development). Using the RS-232C ports, display units can be connected to provide graphic user interfaces on site. The front and side panels are made of aluminum for efficient heat dissipation to realize natural air-cooling. Also, the terminal block is removable, so the main hardware can be replaced without disconnecting the field wiring in the case of a failure.
Figure 3 Software configuration
Figure 3 shows the software configuration. One of the key features of the controller software is that off-the-shelf or existing components are used without or with only minimal modification. The following highlights the features of each component.
The following describes the key features of control applications for the FCN and FCJ.
We completed, as controllers in an NCS, platforms having modulus, highly independent software and hardware architectures into which open technologies and standardized engineering methods are aggressively adopted. We hope that a variety of new solutions that make the most of the advantages of these controllers will be configured. We, as developers, are committed to further improving the FCN and FCJ autonomous controllers through upgrades as well as by adopting emerging state-of-the-art technologies while leveraging users' indispensable resources.
The brick type model FCJ autonomous controller fulfills the basic requirements of the utility control. It also provides the reliability for the SCADA communication with network redundant capability.