YOKOGAWA FFCS COMPACT CONTROL STATION IN CENTUM CS3000 R3

YOKOGAWA FFCS COMPACT CONTROL STATION IN CENTUM CS3000 R3

In the course of developing CENTUM CS3000 R3 Revision 3.04, we also developed a new FFCS field control station which has achieved compact size and high reliability. The processor cards, being compact yet high performance, utilize field-proven “Pair & Spare” technology deployed in large-scale control systems, resulting in the implementation of sophisticated control functions and high reliability equivalent to the existing controllers designed for large-scale control systems. The FFCS is designed to be the same overall size as the existing “uXL” control unit, which enables easy replacement of the control unit without any changes. Moreover, CPU nodes, processor modules, ESB coupler modules, and Vnet coupler modules have been newly developed for the FFCS. Especially, SEN bus (Serial Exchange Nest bus), which is a high-speed serial bus designed to suit the program copy and data equalization between dual redundant processor modules, has been developed as a new technology for data communication.

INTRODUCTION

YOKOGAWA Electric has been using Pair & Spare method as a reliability-enhancing technology for its line of distributed reliability-enhancing technology for its line of distributed control systems (DCS) since the release of the CENTUM CS in 1993. As a result, the system has achieved an availability factor of seven 9’s (99.99999%) for the record of operation to date. Under the basic concept “continually adopt new functions with assured function continuity”, the CENTUM CS3000 R3 is being constantly improved through ongoing development and by introducing the latest technologies. Also strictly adhering to this basic stance for CENTUM CS R3 Revision 3.04, we have developed the FFCS compact field control station (Figure 1), which provides both the advanced control functions and high reliability levels required for DCSs, for use with small- to medium-scale systems. This article introduces the FFCS.

SYSTEM CONFIGURATION

Figure 2 shows the configuration of the CENTUM CS R3 system. As for field control stations (FCS) to be connected to field devices to control the plant, we have added the small-size FCS (compact type, hereinafter called FFCS) featuring both high mountability and high distributability to the existing line of FCSs — standard, expandable and renewable FCSs that realize high mountability, and the highly distributable FCS that is suited for distributed topologies, according to the application capacity and the purpose of use.

FEATURES OF FFCS

Figure 3 illustrates the external views of the conventional field control unit (FCU) and the field control unit (CPU node) of the FFCS and the features of the FFCS are described below.

(1) Compact and Expandable

Positive adoption of the latest technologies has made the FFCS as compact as only one-fifth the volume of the conventional control unit. The number of I/O nodes can be increased up to three. Thus the system can be expanded without increasing the number of CPU nodes.

(2) Advanced Functionality and High Reliability

The processor module employs Pair & Spare method, which is field-proven for controllers for large-scale systems, to switch the control right in case of system failure without any momentary shutdowns, thus minimizing the influence inflicted upon the process. While being compact, the module has the same advanced control functions and highly reliable architecture as those of controllers for large-scale systems. In addition, the processor module can be made completely dualredundant.

(3) Migration from Existing uXL Systems

The external dimensions of the FFCS are the same as those of the control unit section of an existing uXL control system for small- to medium-scale plants. It is therefore possible to migrate to the FFCS by simply replacing the control unit section with the station. This feature enables the user to reuse its existing assets to the maximum possible degree and update the existing system with the minimum investment in the plant and equipment.

HARDWARE CONFIGURATION OF FFCS

As shown in the dual-redundant configuration diagram of Figure 4, the processor module, power unit, communication bus, and I/O module of the FFCS can all be duplexed. The I/O module (IOM) and the field network I/O module (FIO) of CENTUM CS R3 have been made common to each other. This section focuses on the hardware of the newly developed CPU node.

CPU Node

A maximum of eight IOMs can be installed in the CPU node, allowing the CPU node to operate alone as the minimum system of the FFCS.

A maximum of three extension nodes (direct-coupling and remote nodes) can be connected to the CPU node. When connecting the CPU node and direct-coupling node, an ESB bus coupler module (EC401) is installed in the IOM section of the CPU node and an ESB bus slave interface module (SB401) is installed in the extension node. When using the remote node in place of the extension node, an ER bus master interface module (EB401) is installed in the IOM section of the CPU node or directcoupling node.

Processor Module (CP401)

Figure 5 shows the dual-redundant configuration of the processor modules. The dual-redundant processor modules employ the field-proven Pair & Spare method. Each processor module comprises two MPUs, where the MPUs perform the same control computations and the computation results are crosschecked by the collators to detect transient errors. With the dual redundancy of processor modules, the transfer of the control right in case of system failure and the continuation of control are accomplished without any momentary shutdown, achieving high degrees of system availability.