YOKOGAWA FFCS COMPACT CONTROL STATION IN CENTUM CS3000 R3

Figure 6 shows the external view of the processor module. The module has been changed in shape from the conventional card-like form to a modular form in which the internal assembly is encapsulated in a molded housing. For the internal hardware configuration, we reused the hardware assets, i.e., the processor card (CP345) and SB bus interface card (SB301) of the industryproven CENTUM CS3000, and incorporated them into a single module, while maintaining the software compatibility as much as possible. Equipped with the microprocessor which is field-proven as has been used for the industry-proven CP345 processor card, the processor module makes it possible to build scalable systems by using the same system software for small- to medium-scale plants and large-scale plants as well.

In order to mount the CP345 and SB301 on a single module (i.e., to achieve downsizing), we actively adopted a programmable device in a fine-pitched multi-pin ball grid array (BGA) as a largescale integration component, chip capacitors and resistors of 1005 size as small-size components, and new elemental technologies, including build-up boards for densely mounting such components.

The processor module contains a battery pack in order to back up the main memory in case of power failure. However, taking environmental protection into consideration, the conventional nickel-cadmium batteries have been abandoned and replaced with nickel-hydrogen batteries.

SEN Bus

We have also developed the SEN bus for program copying and data equalization between the processor modules. Table 1 shows the specifications of the SEN bus in brief.

Traditionally, data exchange between the processor modules has been performed using a parallel transmission method. In the case of the SEN bus however, the method has been replaced with the point-to-point high-speed serial transmission method to reduce the mounting area and the number of signal lines to onetenth those of the conventional bus. Since the LVDS (EIA/TIA644 standard) method featuring small signal amplitudes has been adopted for the bus signal levels, radiation noise has been reduced and power consumption has also been dramatically reduced. From the point of view of high reliability, we added an errordetecting code and made it possible to connect/disconnect the module with the line electrified. The SEN bus is provided with error-detecting functions, such as constantly performing selfdiagnoses using idle frames even in the absence of bus access requests. From a software point of view, the SEN bus inherits exactly the same interface as that of the existing backplane bus.

Thus the FFCS features a design in which users need not be conscious of the SEN bus.

ESB Bus Coupler Module (EC401)

We have also developed the ESB bus coupler module (EC401) designed to connect the direct-coupling node to the CPU node. The module has one port for the ESB bus to communicate with the ESB bus interface module (SB401). By installing two units of the module, it is possible to support for the dual redundancy of the ESB bus.

V-net Coupler Unit

The FFCS employs the field-proven V-net as the control bus. The V-net coupler unit is equipped with a V-net data link control section and physical layer interface to provide signal isolation and level conversion for the V-net.

CONCLUSION

Yokogawa Electric's DCSs have evolved through the positive adoption of new technologies in line with market requirements (performance, functionality, and capacity increase). We have increased the capacity and functionality of FCSs' control units in harmony with improvements in semiconductor integration technology and enhancements in microprocessor performance. Since the amount of data for equalization between the dualredundant processors has increased significantly, the conventional transfer capacity will no longer suffice.

We have retrofitted the backplane bus which has not been changed since the release of the CENTUM CS. In addition, we have developed the SEN bus (high-speed serial bus) for data equalization between the dual-redundant processor modules of the FFCS. The technical progress of the SEN bus holds promise for the bus to become even faster in future. Consequently, it will become possible to further enhance the functionality and performance of FCSs.

REFERENCES

(1) Matsuda Toshihiko, Sano Hideo, Soggo Sadatoshi, Hazama Meguru, “Fault Tolerant Design for Field Control Stations”, Yokogawa Technical Report , Vol. 18, 1994, pp. 10-13

(2) Komiya Hiroyoshi, Akai Hajime, Matsuda Toshihiko, Nishida Jun, “Fault Tolerance of Distributed Process Control Systems”, The Institute of Electronics—Information and Communication Engineers Technical Research Report, Vol. 97, No. 98, 1997, pp. 35-40 (in Japanese)

(3) Kato Eiji, Nakamoto Eiji, Matsuda Toshihiko, “Features of Field Control Station Hardware”, Yokogawa Technical Report, No. 26, 1999, pp. 6-9

* CENTUM and uXL are registered trademarks of Yokogawa Electric Corporation. The names of companies and products that appear in this document are the trademarks or registered trademarks of the respective holders.