The hardware of tobacco Weighing system is mainly composed of 4 subsystems, which are electronic tag radio frequency identification system (including RFID scanning antenna and RFID reader), electronic weighbridge (including Electronic scale and weighing terminal), data analysis display communication system (PC industrial computer and field display screen) and standby complement system (Bluetooth scanning gun). The whole system adopts RJ45 or RS-232 bus to act as the bridge of communication transmission between the components of the system.

RFID, scanning antenna and RFID reader are the most important components of RFID system. The basic work flow of the whole electronic tag radio frequency identification system, first of all, the RFID scanning antenna in the system sends a certain frequency signal to the periphery, when the electronic tag enters the coverage of the RFID scanning antenna signal, the electronic tag will generate induction current, thus activating the electronic tag; The electronic tag uses the induced current to encode the stored signal and then sends the code out through the built-in antenna in the electronic tag. The reader uses the transmission characteristics of RF signal and spatial coupling (inductive or electromagnetic coupling) or radar reflection to receive the carrier signal returned in the electronic tag, and sends the data to the PC industrial computer for processing after demodulation. Because the electronic tag is powered by the induced current generated by the electromagnetic field. The higher the power consumption of an electronic tag, the closer the read and write distance, and the worse the performance of an electronic tag. Whether the electronic tag can work is mainly determined by the working voltage of the electronic tag, which also determines the identification distance of the radio frequency identification system. However, while reducing the power consumption of the electronic tag as much as possible, there is also a factor worth paying attention to, that is, the transmitting power of the RFID scanning antenna, and the identification distance is proportional to the transmitting power of the RFID scanning antenna, that is, the greater the transmitting power, the longer the identification distance.

After the weighing system finishes weighing the tobacco box, the weighing terminal demodulates the quality signal of the electronic scale and sends it to the PC industrial computer through the RS-232 communication serial port. Considering the openness of the warehouse platform and the installation position of the electronic scale, it is necessary to choose an electronic scale that can cope with the harsh weighing industrial environment, and when selecting the sensitivity of the weighing module, the weighing module with too high sensitivity may be too sensitive to external environmental factors (including the ground vibration and air volume driven by the clamped truck), affecting the stability of the reading; The weighing module with too low sensitivity will affect the accuracy and linearity, and the electronic scale will involve external raw material quality settlement, and the determination of the output sensitivity of the weighing sensor of the electronic scale should also consider the rated range, the output signal of the weighing module, the number of Weighing modules, the excitation power supply and the actual load of the weighing module.

Data analysis display communication system Data analysis display communication system mainly includes PC industrial computer and field display two parts. The role of the PC industrial computer is to receive the information of the electronic label read by the RFID reader through RJ45 network communication, and read the quality value of the tobacco tobacco box and the tray through RS-232 serial port communication, and analyze the two sets of data after processing to determine whether the average quality of the tobacco tobacco box meets the requirements. If qualified, the integrated data will be uploaded to the background database server through RJ45 network communication; If it is not qualified, the on-site operator will be prompted on the on-site display screen to determine the treatment method of the unqualified tobacco box. At the same time, the PC control machine can also modify the power intensity and other parameters of the RFID scanning antenna. In the whole process, the PC industrial computer displays the current system process, electronic label information and data analysis results on the wall-mounted field LCD display through the VGA output interface.

The backup complement system takes into account the uncertainty of the electronic label position on the tobacco box and the limitation of the installation position of the RFID scanning antenna. When the PC industrial computer finds that the number of electronic labels read by the RFID scanning antenna is inconsistent with the number judged by the weighing result after data processing and analysis, The field display will warn that the RFID scanning antenna has missed reading when scanning the electronic tag, at which time the field placed Bluetooth scanning gun can be used to refill the one-dimensional barcode of the electronic tag.

System software design

Through the design of the system software, the following main functions are achieved:

1) Complete the intelligent collection of the quality information of the electronic scale

The active polling receives the quality of the load sent by the electronic earth scale, and automatically determines whether it is the quality information of the pallet or the quality information of the tobacco box or the illegal quality information according to the load material value, and receives the quality information of the pallet and the quality information of the tobacco box.

2)RFID electronic tag automatic recognition

After obtaining the tray information of the electronic scale and the quality information of the tobacco box, the RFID reader is activated to read the electronic label of the tobacco box, read the 27-bit tobacco code in the electronic label, display the 27-bit tobacco code of the electronic label, and display the number of tobacco boxes read. The weighing system needs to query the records saved in the local database and automatically filter the 27-bit tobacco code of the RFID electronic tag that has collected the quality information of the tobacco box to ensure the accuracy of the weighing results.

3) Intelligent judgment of tobacco box quality information

According to the number of RFID tags and the quality information of tobacco box, the average quality of tobacco box is calculated, and then compared with the pre-set value, the weighing result is obtained, prompting the user to weigh the result. Due to the deviation of the weighing result caused by the missing reading of the electronic label, the barcode scanning gun should be used to scan the barcode, and the weighing result should be judged again after the number of tobacco boxes is filled up.

4) Process control

When the system is working, there will be a voice prompt for the operation steps and results. After the successful weighing, if the tobacco box is qualified to be weighed, the system will save its quality information and electronic label information (including the average quality of the tobacco box, 27-bit tobacco code, weighing location, weighing time, status and other information) and upload it to the server. To realize seamless docking with the tobacco management system information of the storage and transportation company, so that the tobacco management system can query and manage the weighing information. If abnormal weighing information is found, the system will prompt manual intervention, and on-site personnel can manually determine whether the abnormal quality tobacco box is in the warehouse.