Transformation of communication protocol between Siemens S7-200PLC and Danfoss inverter_ Old bear passing by_ Sina blog

Siemens S7-200PLC and Danfoss inverter Transformation of communication protocol

　　 Application devices ： Water tank type wire drawing machine

　　 Project brief introduction ： Jiaxing Dongfang steel cord Co., Ltd. is one of the backbone enterprises in the domestic automobile steel cord industry , Water tank drawing machine is the key equipment for manufacturing steel cord . Jiaxing Dongfang steel cord Co., Ltd. has a water tank type wire drawing machine , A Siemens frequency converter and a ABB Frequency converter . After the Siemens frequency converter breaks down , Our company has successfully used Danfoss after careful study of the original equipment VLT5000 Replace the frequency converter , Due to the comprehensive function and high reliability of Danfoss Inverter , The equipment works well , The user is very satisfied with this .

　　 Process description of water tank wire drawing machine

　　 The transmission of the water tank type wire drawing machine is mainly composed of the following three parts （ Pictured -1 Shown ）：

　　1, Setting out ： Adopt passive unwinding , The brake controls the unwinding tension ;

　　2, wire drawing , I.e. mainframe ： Open loop speed control with frequency converter ;

　　3, Roll up ： Linear speed synchronization + Constant tension control , There is dance wheel position feedback , The frequency converter is used for closed-loop process control , Control the position of the dancing wheel .

　　 Description of the electrical control system of the original equipment

　　 The man-machine interface ： Siemens OP270

　　 master control PLC： Siemens S7-226

　　 Main engine frequency converter ： Siemens MM440-22kW Frequency converter

　　 Winding frequency converter ：ABBACS600 Frequency converter

　　 Starting of two frequency converters / stop it , All fault alarms are digital I/O Point control ; The position of the reeling dancing wheel is controlled by ACS600 single

　　 Complete immediately ; The engine speed is determined by S7-200PLC adopt RS485 The serial communication port is given .

　　 The system control block diagram is shown in Figure -2 Shown ：

　　 Description of specific replacement methods

　　 Control line wiring part ：

　　 According to the wiring drawings provided above , Refer to Siemens MM440 Frequency converter and Danfoss VLT5000 Instructions for frequency converter , We can achieve SIEMNES Frequency converter and DANFOSS Replacement of external terminal wiring between frequency converters （ In order to achieve the same logical function ）

 

　　 Modification of communication program ：

　　 Due to the USS Communication protocol with Danfoss inverter RS485 Communication protocols are not fully compatible , So after the frequency converter is replaced , Also right S7-200PLC The communication part of the program is properly modified , To ensure the normal operation of the system .

　　A、 Siemens USS Brief introduction to communication protocol

　　USS Can be called in the program 4 Sub block , They are ： initialization （USS-INIT）、 Control word , Frequency setting （USS-CTRL）、 Read parameters （USS-RPM）、 Write parameters （USS-WPM）. For users, they can read and write parameters as long as they call these four subroutine blocks 、 Communication control, frequency setting and other functions （ The specific use methods of these four subroutine blocks can be found in SIEMNESPLCS7-200 Search in the help options in ）.

　　B、USS The format of the message sent in the communication program is the same as DANFOSS Difference of message format required by frequency converter

　　USS The communication subroutine is named USS-CTRL、USS-RPM、USS-WPM（WORD） The message format sent by the three subprograms of is as follows ：

　　USS The communication subroutine is named USS-WPM（DWORD） The message format sent by the subroutine of is as follows ：

　　 Danfoss inverter RS485 The format of communication protocol message is as follows ：

　　 From the above table, we can know that Danfoss Inverter RS485 Message format and of communication protocol USS-WPM（DWORD） The message format of the subroutine is identical ; And USS-CTRL、USS-RPM、USS-WPM（WORD） Three subprograms only PWE There is a difference of two bytes in the length of . Accordingly , The original PLC Sent in the communication subroutine PWE Change from two bytes to 4 Bytes , You can communicate with Danfoss inverter smoothly .

　　C、 In the message format PCD1（ Control word ）, Siemens inverter is different from Danfoss inverter ; However, the control word function is not used in this application , So I won't go into details here .（ Please refer to USSPROTOCOL and DANFOSSDESIGNGUIDE Instructions ）.

　　D、 Of two communication protocols PCD2（ Bus given ） The definitions are exactly the same , All for 16384（ Decimal system ） Corresponding 100% Given by the bus , Therefore, the frequency setting part does not need to be modified .

　　 summary ：

　　 The starting point for this replacement is Siemens S7-200PLC Transformation of communication protocol with Danfoss inverter , Little impact on peripherals , The user can hardly feel the change in the operation , Such a guarantee is crucial for those users in large-scale manufacturing industry . This successful experience can also be applied to other similar projects .

　　 About Danfoss Inverter MODBUS RTU Communication of

　　 One ：modbus rtu Conventional synopsis

　　modbus The statute is modicom The company has developed an open protocol that is supported by many manufacturers

　　modbus Protocol is a general language used in electronic controller . By this Agreement , Between controllers 、 Controller via network （ Ethernet, for example ） Can communicate with other devices . It has become a general industrial standard . With it , The control equipment produced by different manufacturers can be connected into an industrial network , Centralized monitoring .

　　 This protocol defines a message structure that the controller can understand , And no matter what kind of network they communicate through . It describes how the controller requests access to other devices , If you respond to a request from another device , And how to detect errors and record them . It establishes the common format of the message domain pattern and content .

　　 Two ： Danfoss modbus rtu Concept

　　danfoss Frequency converter is widely used in automation field , As a professional frequency converter supplier ,danfoss It has been one of its key tasks to improve the communication application level of products . be based on modbus rtu agreement ,danfoss The corresponding control integrated card is developed , Through this integrated card danfoss The frequency converter can be operated in the form of modbus rtu The agreement is convenient for scada and hmi And so on .

　　danfoss vlt2800 or vlt5000（ It has been discontinued ） Series frequency converter modbus rtu Communications

　　 And fc300 The communication of series frequency converter is similar

　　 3、 ... and ：s7-200、 Delta plc Wiring with Danfoss frequency converter ：

　　s7-200 dsub9 danfoss

　　3----+------------------68

　　8------------------------69

　　 Delta plc

　　 Positive signal +---------------------68

　　 negative signal -----------------------69

　　 Four ： Parameter setting of Danfoss frequency converter

　　1．vlt5000（ It has been discontinued ） or vlt2800 Relevant communication parameter settings of frequency converter ：

　　561#---------2----rtu agreement

　　500#---------1----485 The address is 1

　　501#---------5----9600

　　570#---------0----1 Stop bit ,even check

　　 Other parameters use initialization parameters

　　2．fc300 or fc51 Relevant communication parameter settings of frequency converter ：

　　8-30-----1----rtu agreement

　　8-31-----5---- Address

　　8-32---------- Baud rate

　　8-33----------1 Stop bit ,even check

　　 5、 ... and ：plc Program example of

　　 If the frequency converter is equipped with mco305 Sync card or profibus card , This communication function is occupied .

　　 Example ： 1） If it's Delta plc, The data address is the parameter number p*10-1,

　　 Such as 3-10 For reference value, the address is 3099

　　2） If Siemens s7-200 Of plc, The data address is prefixed with the parameter number 4p And ride on 10,

　　 Such as 3-10 For reference value, the address is 43100.