FLXA21 Modular Two-wire Liquid Analyzer in FLEXA Series FLXA21 Modular Two-wire Liquid Analyzer in FLEXA Series *1 *1 Ryuji Chiba Shinjirou Kiyono *1 *1 Takeshi Houkita Yukihiro Seki Yokogawa has developed the FLXA21 two-wire liquid analyzer as the first product in the FLEXA series. The FLEXA series, named after “Flexible EXA,” is a successor of the EXA series with advanced configurability and expandability. The FLXA21 is a successor of four EXA202 series products: pH/ORP analyzer (ORP: oxidation-reduction potential), contacting conductivity analyzer, inductive conductivity analyzer, and dissolved oxygen analyzer. FLEXA series was designed to put together common functions and have independent sensor parts, forming a modular architecture that allows easy assembling. This report introduces the specifications and functions of the FLXA21 and describes its hardware and software structure. INTRODUCTION okogawa has been offering the EXA200 series two- (1) Ywire liquid analyzer for processes since 1990 . This analyzer has been used in various fields including the quality control of raw materials in process plants in the electric power and petrochemical industries, reaction management of products, quality control in waste water facilities, and quality monitoring of river water and tap water. The FLXA21 two-wire liquid analyzer, the first model of the modular-designed FLEXA series with flexible system configuration and expandability, is based on Yokogawa’s long experience and achievements in process analyzers. The Figure 1 External View of FLXA21 FLXA21 is a successor of the PH202 pH/ORP analyzer (ORP: oxidation-reduction potential), SC202 conductivity/resistivity FEATURES analyzer, ISC202 inductive conductivity analyzer, and DO202 dissolved oxygen analyzer. The FLEXA series is a successor The enhancements made in the FLXA21 compared to of EXA series and is named after “Flexible EXA.” The existing models are as follows. FLXA21 offers improved operational performance, increased number of connectable sensors, and lower price than existing ● Support of multiple sensors products. Each function is modularized, allowing the products ● Improved HMI functions to be quickly shipped to anywhere in the world and the lineup ● Improved diagnosis of sensor part to be extended merely by developing dedicated modules. This ● Increased housing options modular architecture also enables response to far shorter product development cycles required in recent years. Support of multiple sensors Figure 1 shows the external view of the FLXA21. The FLXA21 can connect up to two sensors of the same The housing is made of coated stainless steel (SUS). An type among pH, conductivity, and dissolved oxygen sensors, electropolished SUS case as well as polycarbonate (PC) plastic first in the industry as two-wire liquid analyzers. Users can case are also available. monitor measured values from two sensors on the display or through HART communication. In addition, calculations of measured values such as calculating the difference or mean of *1 Analytical Products Business Center, two measured values at different points, can be performed by a Industrial Automation Business Headquarters single FLXA21, for which two analyzers were required until now. 43 Yokogawa Technical Report English Edition Vol.53 No.2 (2010) 105 FLXA21 Modular Two-wire Liquid Analyzer in FLEXA Series The first sensor With this function, users can configure a redundant Tag: FLXA21-PH pH The second display item 25 °C system and continue measurements during calibration. The first display item The third display item 19 mV 10.38 Healthiness of sensor Hold and washing state display In a redundant system, measurements can be continued (during the relevant state) Tag: FLXA21-PH pH The second sensor 24.9 °C even while repairing or replacing a faulty sensor. The FLXA21 24 mV 6.35 can measure the same point with two sensors, so if one sensor 4 mA PH1 20 mA fails, the output is automatically switched to that of the other Analog output display Alerts and failures display (value of the first sensor) (only at occurrence) sensor that is working properly. (a) Example of home screen Manual switching of measurement outputs is allowed Tag: FLXA21-PH1 as well, and this enables measurements during calibration. To the home screen In previous models, measurements had to be suspended for The first display item To the detailed display screen calibration to be carried out, and measured values etc. just 10.38 TEXT_PH1 pH To the device state screen before the suspension were being sent to the upper system 25 °C TEXT_TEMP1 The second display item The third display item 19 mV TEXT_ORP1 during the calibration. In the FLXA21, measurements can To the device setting screen 4 mA PH1 20 mA be continued by switching the output from the sensor being (b) Example of main screen calibrated to the other sensor. Tag: FLXA21-PH pH1 These functions enable building of a highly reliable 10.38 pH 12 Maximum value till last display refresh Current measured value system with backup function, reduce installation cost, and 8.4 save installation space. 5.6 Minimum value till last display refresh 2.5 12:00 12:20 12:40 Improved human machine interface (HMI) functions Time Dot-matrix LCD „ Maximum value Mean value The LCD display was upgraded from the character display Minimum value type to the 3.3-inch black/white reflection type with 213 x (c) Example of trend display screen 160 pixels, achieving graphical display of more information. Figure 2 shows examples of the screens. Figure 2 Examples of Display Screen Images 1) Major display screens „ Adoption of touch screen The key display screens for measured values comprise The touch screen system which enables operation at the the home screen which shows the values from two sensors front offers a more interactive HMI than previous models. Any and the main screen which shows the values from individual item can be directly selected from multiple choices. Displays sensors. Besides the primary measured value, they display two of touch target areas were removed from display screens for auxiliary measured values, tag name, current outputs, a bar simple operations such as transition from the home screen to graph to show the healthiness of the sensors, and the state of the main screen or return to the main screen from the trend the device. Switching between the home and main screen can display screen, which frees up space for displaying useful be performed by one touch operation. The main screen leads information. to more detailed display screens. Moreover, confirmation messages displayed when setting critical items are easy to Improved diagnosis of sensor part understand, detailed information for the quick setup function The sensor diagnosis function has been improved by enabling easy setup is displayed, and detailed contents of adopting a bar chart display. The healthiness of the sensor errors and their countermeasures are displayed when errors judged from the calibration results is displayed in a simple occur. Routine operations can thus be carried out without bar chart. It also includes historical information such as referring to the instruction manual. accumulated measuring time of the sensor and the number of 2) Trend data display screen heat shocks to the sensor. By setting the system to display the The display can show trend data of up to two weeks on up worst state among multiple items regarding the healthiness of to three screens. Long-term measurement fluctuations can be the sensor on both the main and home screens, the healthiness easily confirmed by only FLXA21 without connecting to the can be checked on the screens usually used. upper system, etc. 3) Support of multilingual function Increased housing options For convenience worldwide, a multilingual function Although previous models were housed in a aluminum is provided for the different languages used in main sales coated case regardless of the installation environment, two territories. The seven languages provided at present including types of housings have been developed to allow the FLXA21 Japanese and English will be increased to 12 languages by the to be installed in a wider range of environments: a PC end of 2010. plastic casting and SUS spinning housing. The SUS housing comprises electropolished type and coated type, making three types of case in total. The low-price PC plastic case is for installations in 106 Yokogawa Technical Report English Edition Vol.53 No.2 (2010) 44 Measured value (pH) FLXA21 Modular Two-wire Liquid Analyzer in FLEXA Series environments where metal cases is not required, the coated CPU assembly SUS case is for harsh environments, and the electropolished The CPU assembly is arranged on the front face of the SUS uncoated case is offered for installations where paint case, and consists of the LCD for display and touch screen for peeling could be a problem. All types can be installed outdoors operation. It receives data from the sensor module and displays and comply with degrees of protection of IP66 of IEC 60529/ it on the LCD, and has a function for sending operational JIS C0920. information from the touch screen to the sensor module and The case is also modularized, and the three types of cases a communication function with external HART devices use common parts for most of their components. Figure 3 (excluding physical layer). shows an internal configuration of the SUS case with coating The main CPU has 512 KB of flash memory for storing for the FLXA21. The main parts shown in the figure are the routine operation programs, and another 2 MB of flash common parts used in the three cases. memory for screen information of all sensors, multilingual information, etc. The latter memory is only for storage; it is used only for identifying the sensor module during the assembly process and to select the language at start-up, and is not used in usual measurement operations, thus achieving low- power consumption. Power board assembly The power board assembly is arranged in the innermost part of the case, and is connected to the CPU assembly via a flexible cable and with multiple sensor modules via a flexible PWB. This assembly generates the power required for the CPU assembly and each sensor module from the external power supply and supplies it to the CPU assembly and each module, Figure 3 Internal Configuration of FLXA21 and has a control function of the physical layer of the HART communication and a current control function. It also serves as a backboard for sensor modules; multiple sensor modules MODULAR ARTCHITECTURE OF FLXA21 can be inserted into it. The FLXA21 accommodates only two As shown in Figure 4, the FLXA21 contains the CPU modules because of the allowable power consumption, whereas assembly, power board assembly, and sensor modules (referred the FLEXA series including a four-wire system type can to I/O modules in the FLEXA series), and each assembly accommodate up to four modules. To prevent cable connection and sensor module is connected by a local bus. The local interference between upper and lower slots, the sensor module bus with simple functions of only serial communication and uses a staggered arrangement for screw positions, each shifted power supply does not restrict the hardware configuration by a half pitch. and enables response to various protocols only with software implementation. The communication specifications in the Sensor module FLXA21 are 9600 bps, 1-second cycle data refresh, variable- The sensor module is categorized as an I/O module length data with cyclic redundancy check (CRC), and single- in the FLEXA series. The main functions are: converting master multi-slaves communication. The data frame format signals from sensors to electrical signals at the preamp and was developed exclusively for the FLEXA series. converting them to corresponding physical values based on the individually calibrated values saved in the EEPROM, and sending converted physical values via the local bus. Preamp LCD Internal A/D converter DC/DC converter To accommodate two modules, the power consumption of communi- CPU cation respective sensor modules for pH/ORP, conductivity, and EEPROM 2M Flash • Main CPU Power supply • dissolved oxygen was suppressed to 15 mW or less. Figure 5 control EEPROM Power • DC/DC supply • shows the external view of the pH/ORP sensor module. • HART Sensor module Unlike the CPU and power board assemblies, the sensor Touch screen communication control Sensor module module is enclosed in a resin case for easy handling. While CPU assembly I/O module Power board assembly having adequate reliability, the set-in sensor case and laser Housing assembly I/O module marking systems for the case have reduced manufacturing Internal Power supply communication costs. M4 screws are used for the terminals for external connections, which allows them to be connected with pin connectors, a standard for sensors. They all serve as terminals Figure 4 Modular Architecture of FLXA21 for relay and analog output modules, which will be developed Each assembly and function module is described below. in future as I/O modules. 45 Yokogawa Technical Report English Edition Vol.53 No.2 (2010) 107 FLXA21 Modular Two-wire Liquid Analyzer in FLEXA Series combinations of functions, or develop expensive all-in-one products and stock them. It was thus very difficult to respond to short delivery schedules. In contrast, for the FLEXA series, it is sufficient to keep inventory of I/O modules for each function and basic housings, and assemble them as required at the overseas affiliates. Once the customer decides the specifications, products can be delivered immediately. Although the FLXA21 as a whole complies with intrinsic (a) Top view safety explosion-proof regulations just like previous models, the replaceable sensor module part and housing excluding the sensor modules shall be designed to conform to the regulations respectively. This will enable easy assembly of the FLXA21 (b) Terminal side view conforming to the regulations with the parts themselves Figure 5 External view of Sensor Module conforming to the regulations at any factories other than (pH/ORP sensor module) certified factories. CONCLUSION The FLXA21 has a function to save the same calibration data in the CPU assembly in case of failure of a sensor module. We have described the FLXA21, the first product in the The calibration data of the sensor can be restored should a FLEXA series. Following the development of the FLXA21, trouble occur. we will expand the lineup of the FLEXA series by making it comply with intrinsic safety explosion-proof regulations as EXPECTED FUTURE DEVELOPMENT mentioned above, making it comply with SIL2 (SIL: safety OF THE FLEXA SERIES integrity level; a safety level defined by IEC61508, etc.), The FLEXA series consists of assemblies and sensor supporting the FOUNDATION Fieldbus, developing the four- modules, enabling a flexible and extendable system to be wire multi-sensor/multi-output transducer, etc. Thus, we built. For example, to develop four-wire transducers, it is will enhance a wide variety of functions of the analyzers. merely necessary to develop an AC power supply assembly The FLEXA is a flexible system that can handle new sensors and I/O modules such as digital input/output (DIO) and analog available in future. This will help extend Yokogawa’s analyzer input/output (AIO) modules. Another CPU assembly can lineup. be developed to allow the analyzer to support a color LCD. REFERENCES Furthermore, developing a module dedicated for a new sensor (1) Teruyoshi Minaki, Masashi Takeisi, et al., “EXA PH 2Wire Intelligent available in future will expand applications. This suggests pH Transmitter Model PH200G/PH200S,” Yokogawa Technical that the FLEXA series can be deployed not only for a liquid Report, Vol. 34, No. 1, 1990, pp. 61-64 in Japanese analysis but also for other analyses. As previously described, I/O modules can be handled * FLEXA and FLXA are registered trademarks of Yokogawa Electric as ordinary parts, which facilitates maintenance. This also Corporation. * HART is a registered trademark of HART Communication Foundation enables the analyzers to be easily assembled at any overseas (HCF). affiliates in the world to meet short delivery schedules strongly desired in overseas affiliates recently. To deliver previous models quickly, we had to stock inventory of various 108 Yokogawa Technical Report English Edition Vol.53 No.2 (2010) 46