Abstract: This paper introduces an important role in the multi-serial card in the loading metering system in the metering system, and examples have explained the working principle and system operation of this measurement system. Evaluation. First, the introduction of the metrics is one of the main means of corporate materials. However, in actual work, cheating in the metrics is quite common, and more complicated, harm is not underestimated. 1. The artificial invoice vulnerability is more. Most companies still use artificial invoices. Because of the randomness of artificial counts, there is no constraint, and some companies' individual Si scales even bring the scale code settlement order and signature, and invoice at home. 2, vehicle body positioning and dynamic weighing counting problem. The current industrial earth balance is measured by static weighing, buyers or sellers often serve the scratch staff, waiting for the goods to slowly through the scale, only the front wheel or the rear wheel is in the scale plana, press printing The button starts printing the metering ticket. Thus the scale is often much more tons. 3, repeat the elimination of scales. Due to the lack of effective technical control, buyers or sellers often repeat the metrics, repeat the print scale code, and the library personnel will be monitored. 4. Change the car back to the paint cheating. Some of the technical control measures taken by some companies have a certain vulnerability. The scratch staff take the same number of car, the big car is over the scale, the car is backing the paste, or the car is overbearing, the big car is backing the skin to achieve cheating. To effectively restrict the work of overcoming the geometers of the metrics, there is a need for a relatively comprehensive technical control measures and a sound management system constraint. The technical control measures are the basis for establishing a management system. In such cases, the flowmeter metering system has played a powerful advantage, and has received good results and bringing benefits to enterprises. Second, the constituent structure system is simpler as follows:
The protocol used is:
Third, the serial communication technology Introduction RS-232C and RS-485: The computer and computer or computer and terminal data transfer can be used in two ways of serial communication and parallel communication. Since the serial communication method has less lines, low cost, especially during remote transmission, avoiding the inconsistency of multiple line characteristics is widely adopted. When serial communication, both parties require communication to use a standard interface to make different devices can easily connect to communications. The RS-232-C interface (also known as EIA RS-232-C) is the most commonly used serial communication interface. Its full name is "Data Terminal Device (DTE) and Data Communication Interface Technology Standards" This standard specifies a DB25 connector of 25 feet. Since the RS-232-C interface standard is earlier, it is inevitable, there is a shortcomings of the following four disadvantages: (1) The signal level value of the interface is high, and the chip of the interface circuit is easily damaged, and because of the TTL level. Do not compatibility with the level conversion circuit can be connected to the TTL circuit. (2) Low transmission rate, the range of communication bauds is 0 ~ 20 kbps. (3) The interface uses a signal line and a signal return line to constitute a common land, which is easy to generate common mode interference, so the anti-noise interference is weak. (4) The transmission distance is limited, and the maximum transmission distance is 50 feet, which is actually only within 15 meters. For the lack of RS-232-C, some new interface criteria have emerged, and RS-485 is one of them. When the communication distance is required to be several tens of meters to thousands, the RS-485 serial bus standard is widely used. The RS-485 is received by balanced transmission and differential, so it has the ability to suppress common mode interference. Plus the bus transceiver has high sensitivity, which can detect a voltage as low as 200 mV, so the transmission signal can be recovered outside of kilometers. RS-485 uses a half-duplex mode of operation, and it can only be in the send state at any time. Therefore, the transmission circuit must be controlled by enable signals. The RS-485 is very convenient for multi-point interconnections, which can save a lot of signal lines. The application RS-485 can be connected to the distributed system. The maximum transmission distance of the RS-485 interface is 4,000 feet. It is actually more than 3,000 meters so that users can easily establish a device network using a single RS-485 interface. (Figure 2)
Because the RS-485 interface has good anti-noise interference, long transmission distance, and multi-station capabilities such as the preferred serial interface. The half-duplex network consisting of the RS-485 interface, generally only two wiring, so the RS-485 interface is transmitted with shielded twisted pair. The RS-485 interface connector adopts DB-9 (apertures) with the intelligent terminal RS-485 interface with the intelligent terminal RS-485 interface, and the keyboard interface RS-485 is connected to the keyboard interface RS-485. Multi-serial port conversion card (CI-134): Due to most of the standard serial ports used on the current computer, it is an interface to the RS-232C. This requires an interface conversion card to perform data conversion. Industio Ci-134 is an RS-422/485 four-way card designed for industrial environmental communication applications. Supports 4 independent RS-422/485 serial ports, up to 128 devices in a pair of multi-point communication applications. In order to make RS-485 2-line half-duplex operation more simple, each CI-134 card has data flow to automatic control (ADDC), no software operation. Therefore, the RS-485 semi-duplex protocol can be controlled without additional coding in Windows applications. To achieve the requirements of high-reliability products, this product provides selectable photoelectric isolation (2 kV) and surge protection (25kV ESD). And built-in termination resistors can be easily applied to remote communication. This serial card is widely used in: multi-point data acquisition; factory automation, remote serial equipment control, industrial control, embedded industrial machinery and SCADA systems.
IV. Detailed Function Detailed below The sixth branch of China Petroleum Daqing Natural Gas Corporation will give a brief explanation of the principles and functions of the flow meter meter system. 4.1 System principle This flowmeter metering system includes computer monitoring management programs (force control 2.0 configuration software, "forceControl2.0), multi-serial conversion card (CI-134IS), mass flow meter (Rosemont), automatic cutting Valve (two-stage), control system (Optomux B100), emergency stop reset button, control mode can be fully automated. In this system, the status of the on-site loading state is completed by the Great Ceremony 3D configuration software control 2.0, communicating through multi-serial card and control system, mass flow meter (SERIES 2000) and display (Daqing 3D system). Among them, the control system is connected to the fast cutout valve, the emergency stop reset button, and the ground signal. The mass flow meter is used to calculate and the transient flow, temperature, density, volume accumulation amount and quality accumulation amount in the line. Since it is a digital signal transmission, the problem of transmitting data single and pulse cumulative precision is avoided by simulation or pulse mode, ensuring accuracy and reliability of metering data; power control software collects from the transmitter of mass flow meters The data is processed, and then set to a dedicated display mounted to each loading crane position, so that the operators and drivers on site can easily understand the progress of the car. In an emergency, both field operators and control room operators can use buttons to turn off the fast shut-off valve, the process is: the control system (PLC) acquisition and process the switch signal obtained by the front button, and then locally lock or reset according to it. Control the status of the fast cutting valve. 4.2 Control Process In order to achieve monitoring management, it is possible to store, query and build day, month, season, annual report. In the upper computer of this set of measurement systems, the status monitoring and data management are implemented separately. Power Control 2.0 collects and transmits on-site data through multi-port card, that is, the host block, and then transmitted by the ODBC data source interface, and the obtained loading amount and the loading crane bit number are developed by Microsoft Visual FoxPro 6.0. In the database management module, the computer automatically prints settlement tickets and generated reports. The specific functions are: force control: real-time collection and display of live data, control, automatic voice tips, and alarm, real-time, time-time trend display, network release data, dual hot standby, etc. database management (VFP : Calculate pre-installation, storage, query, retrofit record, generated report, etc. This flowmeter measurement system is: 1. When the vehicle is ready to load, the vehicle management data record is made in the control room. In the database management program, the operator automatically calculates the pre-assembly amount according to the can body volume and media density input by the operator. 2. The vehicle reaches the strap of the strap and ready, the control room operator gives the high-speed shut-off valve automatically on the display of the display of the load to the LED. When approaching 95% of the load target value, the control system will quickly cut off the valve to a small flow state (such as 5% of the full flow), and emit a sound and light alarm, remind the vehicle personnel to pay attention. When the actual loading amount reaches a predetermined target value, the control system turns off the cut valve and stops the car on site. It is also possible to use a rough two pipelines to refuel for only one flow meter, and are controlled by two valves.
When approaching the target value (such as 95%) first turns off the valve on the coarse line, then close the valve on the fine line to ensure the accuracy of the loading. 3. While issuing the valve action, the control room automatically transmits the data from the monitoring software to the database management module, and the operator controls the printing load metering settlement order, supplied to the user. At this point, the entire loading process is completed. 4. In order to ensure the need for the progress of the loading, any position of each loading can be loaded at any time, and the computer can meet the requirements of the parallel car, and there is no conflict. 5. Introduction to the voice prompt: Two explosion-proof speakers are installed on the on-site loading pallet, and a microphone has a microphone with the site. When the load starts, the configuration software triggers a previously recorded sound file, such as the "second crane bit load"; when the load is 95% of the pre-loaded amount, the computer outputs a sound file on the site. For example, "the second crane loader is ready to end"; when the load is completed, the other sound file is output, such as the "second crane load". Thus, on-site operating work can master the progress of the loading, making the loading work smoothly. 4.3 The two-machine hot standby has a multi-gate-port conversion card in the two upper machines, and the power control software has a double-haired hot standby function, which can specify a machine as the host, another as a slave, slave content Synchronize with the host content, from the machine to monitor the host status, once the host stops responding, take over control. The "Double Machine Backup" mechanism can also greatly improve the reliability of the system operation. When the host is stopped, when it is unable to receive the data of the remote device, the position of the host is immediately replaced by the host, and the data collection is continued. The system operation does not have to stop, greatly mitigating the pressure of the user in the system, while allowing the company to reduce the loss caused by the system. V. Summary Multi-serial card has played a very important role in loading metering work. Since RS-485 has the characteristics of communication stability, anti-interference, communication distance is far, making the system have increased rich practicality. This system can also access the serial device networking server (NPORT Express) to connect to other network connections, implement resource sharing, and publish all records and reports generated by powerful Web Server to other management or control networks, Make the company's leadership can see the status of the on-site loading status in their own office, as well as related reports in the computer, facilitates the company's integrated management, increasing the scalability of the system. This system has received extensive attention and recognition in the industry, and puts into operation in the following projects: References: [1] "Monitoring Configuration Software and Its Application" Ma Guohua Tsinghua University Press [2] multi-string card use instructions And function introduction MOXA website
