Hongke dry goods | teaches you how to parse floating-point data in MODBUS

Preface

Industrial raspberry pie support MODBUS TCP/RTU Communication protocol , therefore , In the use of Modbus Protocol temperature and humidity sensor 、 Electronic balance 、PLC And other devices are widely used . When industrial raspberry pie as MODBUS TCP/RTU Master station time , You can connect at most 30 A slave device , thus it can be seen , Industrial raspberry pie has good scalability .

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One 、 challenges

        MODBUS Slave station equipment includes 16 Bit integer data , But the application is more 32 Bit floating point data , This is because 32 Bit floating-point data can be controlled more accurately in the communication process , This kind is often used for weight data such as electronic balance 、 Temperature of temperature and humidity sensor / Humidity data 、 Motor speed and other scenarios .

        But in this process, we will face the problem of data analysis ： The application of floating-point data needs to follow IEE745 Data conversion rules , To realize the conversion and utilization of integer data .

        Register can only store 16 Bit data , So floating point data will be split into two data parts , Stored in two adjacent registers , As follows ：

1. When reading data , You need to restore the two register data into floating-point data through data analysis （ Pictured 1 As shown in ）;

2. When writing data , Through data analysis, a floating-point data is divided into two hexadecimals and written into the corresponding registers （ Pictured 2 As shown in ）. chart 1.  The register data is merged into a floating-point data graph 1.  The register data is merged into a floating-point data graph 1.  Register data is merged into floating-point data

chart 1.  Register data is merged into floating-point data  

chart 2. Floating point data is written to register  

Two 、 Solution

        In response to such problems , Hongke provides an analytical method , As follows ：

1、 Read two register data , Combine the two register data into floating-point data through bit operation .

2、 Write a floating point data , Put 32 Bit floating-point data is split into two 16 Bit integer data , Write to two registers respectively .

 

 

3、 ... and 、 summary

      Industrial raspberry pie uses Debian System , High open source , Can pass C/C++、Java、C#、Python Etc . About converting floating point data into 16 There are many methods that can be used to parse hexadecimal integer data , The above is only one of the data analysis methods , There are errors in this analytical method , The error range is ±0.01, It can be applied to the situation that the precision of floating-point data is not particularly high . For the above scenarios , If there are other parsing methods , Welcome to add engineers to wechat for communication .

Four 、 Project introduction

        Hongke industrial raspberry pie products have real-time Raspbian System , built-in Broadco Multi core processors have the ability to process complex tasks such as image processing .

        Besides , It's small and flexible , Low power consumption , Support with Python/Java/C/C++/C#、Node-RED Visual programming tools for development , Also can realize CPDESYS soft PLC function , It can help users quickly create applications in scenarios such as data acquisition and small-scale control , Realize industrial Internet of things and digital production .

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