Zhou Xu

(School of Electrical Engineering,Shandong HUAYU University of Techonology,Dezhou,Shandong 253034)

Abstract:Design an innovative service system of filter press IOTbased on NB-IOT.Collect the running data of the equipment,including the running time of the equipment,fault code,running current of the motor,and running pressure of the hydraulic cylinder,and upload it to the cloud server.Iot customer innovation service system software,can real-time display equipment information.The collection module based on hardware and the mobile APPconstitute the iot customer innovation service system,which identifiesthe serial number of the equipment,corresponds to the customer terminal,and provides timely maintenance suggestions for the filter pressfor customers.

Keywords:NB-IOT;IOT;filter press

As an important link in the sewage treatment industry chain,the development of filter press in China has been attracting much attention.By 2019,China"s annual sewage treatment capacity will reach 57.5 billion tons and annual sludge output will be about 45.6 million tons.When the filter press is working,staff should be on duty.The working time of the filter press cannot be recorded in time and man-machine interaction cannot be realized.With the development of society and the improvement of automation,customers have put forward new requirements on the filter press,that is,to improve the automation level of the filter press,in order to achieve interconnection and interworking,automatic data collection,remote debugging,remote fault analysis,human-machine interaction,unattended function.At present,there is no NB-IOT based on IOT system for filter press in China.The manufacturer cannot remotely read the operating parameters of the customer equipment.The problem callsfor an immediatesolution.

In response to the above problems,we developed an innovative service system for IOT customers of filter press based on NB-IOT.Under the general trend of"Internet of everything",NBIOT has the characteristics of strong connection,high coverage,low power consumption,low cost,etc.,which can bring richer application scenarios[1].Monitor filter parameters through computer web pages or mobile APP.IOT of filter press data can improve the technical content of filter press products and enhance the competitiveness of products.Through big data analysis,master the opening probability of filter press equipment,make the equipment running time,respond to market changes faster and updateproducts.

Single chip microcomputer is used as the control core and external network communication chip to transmit the data collected through the serial port to the cloud server.MCU internal programming to achieve MODBUS protocol,so as to achieve the communication between the MCU,PLC,intelligent instrument[2].The cloud service plans to adopt baidu cloud server,which supports MQTT protocol and can realize real-time data transmission.HTML5 technology is used to write web pages on PC and mobile phones to display the collected data[3][4].Write APP on mobile phone to realize remote monitoring and control function of mobile phone on industrial site.Thesystemcomposition isshown in figure 1.

Figure 1 IOT Customer Service System Diagram of Filter Press

MODBUS communication implementation.Based on NB-IOT communication network,data is directly sent to the server without gateway[5].Single chip microcomputer as the main control chip,using network transmission as wireless transmission.Write an APP on the mobile phone for data display and remote control.Program communication flow chart asshown in figure2.

Figure 2 Communication Flow Chart of Host Sending Program

We choose the MCU with WIFI function ESP8266,write MODBUS communication protocol in MCU,read the PLC internal address data.MODBUSprotocol is a universal language applied to electronic controllers[6]. This protocol allows controllers to communicate with each other,controllers over networks such as Ethernet,and other devices.This project USES RTU mode,and the message sending should start at a pause interval of at least 3.5 characters.The first field of transmission is the device address.The available transfer characters are hex 0～9,A～F.The network device continuously detects the network bus,including the pause interval.When the first domain(address domain)is received,each device decodes it to determine whether to send it to itself.After the last transmission character,a pause of at least 3.5 characters marks the end of the message.A new message may begin after this pause.The address field of the message frame contains two characters(ASCII)or 8 bits(RTU).The master device gates the slave device through the address field that the slave device to be contacted puts into the message.When a response message is sent from a device,it puts its address in the address field of the response so that the host knows which device is responding.Address 0 is used as the broadcast address so that all slave devices can recognize it.In the reply packet,data includes data byte length+data value,while in the request packet,data only contains data value.Through the above methods,each coil of MODBUS isread and written[7][8].

Use of NB-IOT networks.NB-IOT network registration and information transmission.Using Shanghai YIYUAN chip,the telecom NB-IOT base station has been installed near the school,therefore uses a telecommodule.First insert the SIMcard and then write the IMEI number.The procedure is as follows:first execute the command AT+CFUN=0,then execute AT+NTSETID=1 and set the IMEI number.After setting,execute AT+CGSN=1 to check whether the setting is successful.The IMEI number can only be set once.The next step is to attach the network.After receiving UDPdata,when we send data to the server through instructions,the operator opens a short channel for the module and the server,and the address of the module is the addresswhen wereceivedata.

IOT innovation customer service system software development.IONICis an open source,free codebase for developing hybrid mobile applications.The framework can run on PC and mobile.Within the software we use the MQQT protocol to send and receive server messages.The steps are as follows:(1)Connect to the server.After the network connection between the client and the server is established,the first message sent by the client to the server must be the CONNECT message.On a network connection,the client can only send the CONNECT message once.The server must treat the second CONNECT message sent by the client as a protocol violation and disconnect the client.The payload contains one or more encoded fields.This includes the unique identifier for the client,the Will topic,the Will message,the user name,and the password.In addition to the client ID,all other fields are optional and are used to determine whether they need to be included in the mutable header based on the flag bit.(2)Publish the news.PUBLISH controlling message means to transmit an application message from the client side to the server side or the server side to the client side.(3)Subscribe to the topic.The client sends the SUBSCRIBE message to the server to create one or more subscriptions.Each subscription registration client cares about one or more topics.To forward an application message to those topics that subscribe to a match,the server sends a PUBLISH message to the client.SUBSCRIBE messages also specify a maximum QOS level(for each subscription)from which the server sends application messages to the client.

Through above hardware system debugging and software data transmission,the application of NBIOT based IOT customer innovation service system in the filter press realizes the remote maintenance of the equipment.Using the latest NBIOT network,the filter press data acquisition is stable and reliable.The adoption of nb-iot based IOT customer innovation service system can reduce equipment maintenance time,improve equipment utilization and increase enterprise profitability.