Profibus is one of the most successful field bus in Siemens PLC inverter Communication ABB the Siemens PLC inverter Communication ABB industrial control system, and it has been widely used. A company gas and press control system uses the Profibus-DP process field bus communication technology, the use of SIEMENS's PLC S7-300 and ABB ACS600 inverter.
2 system configuration and communication protocols
(1) system configuration
The system is based on the related products of SIEMENS Corporation and ABB company to realize the communication and control principle of the full digital AC speed regulation system in Profibus-DP network. Which SIMATIC for SIEMENS's S7-315-2DP PLC, inverter for the ACS600 series, NPBA-12 for the inverter with the communication adapter. Programming software for the V5.2 STEP7 software for PLC S7-300 programming and the Profibus-DP network configuration and communication configuration. PC screen operation using WinCC5.1 programming and operation, and PLC communication using Ethernet communication.
(2) communication protocol
In this system, PLC S7-300 is used as the master station, and the converter station is the main station to transmit the operation instructions to the inverter. Inverter and NPBA-12 communication adapter module connected to the Profibus-DP network as a slave station to receive from the master S7-315-2DP SIMATIC to control. The NPBA-12 communication adapter module will be stored in the process data received from the Profibus-DP network into the bidirectional RAM, each word is addressed, and the bidirectional RAM can be sorted by the data of the converter, and the control word is written to the inverter.
From the software point of view, the core content of the fieldbus control system is the communication protocol of fieldbus. The data message structure of Profibus-DP protocol is divided into protocol header, network data and protocol layer. Network data is PPO including PKW and process data PZD. Parameter PKW is a function code to be defined by the converter. The process data PZD is a data value that is to be input / output in the process of converter operation. Profibus-DP a total of two types of network PPO: a class is no PKW and there are 2 or 6 word PZD; the other is a PKW and there are 2 word, 6 word or 10 word PZD. The purpose of classification of network data is to accomplish different tasks, that is, the transmission of PKW and the transmission of PZD are not affected, so that the inverter can be operated according to the instruction of the upper level.
3 the STEP7 project systems configuration and communication program
(1) using the STEP7V5.2 configuration software, enter the Configure S7-300 to complete the PLC Hardware hardware configuration;
(2) select S7-315-2DP as master station system, the GSD NPBA-12 () file into the STEP7 programming environment, the software configuration NPBA-12 to S7-315-2DP as the master of the DP online, and selected the use of PPO type, the design use PPO4, set the site network address. In the structure of the variable frequency drive device, the ABB converter uses Profibus-DP communication module (NPBA-12) for data transmission, which is mainly periodic: the host from the station reads the input information and sends the output information back to the station. Therefore, it is required to call two system function blocks SFC15 and SFC14 to read and write the data in PLC main program;
(3) a data block is built in the main PLC program for data communication of the inverter, and a variable table is set up to observe the effect of real-time communication.
4 converter run settings
With the application of Profibus-DP in the PLC field bus network, in addition to the PLC automation system in the programming, the appropriate parameters are also set up on each frequency converter.
After the communication cable is connected, the converter is started, and the communication parameters of the inverter are accomplished
4.1 Basic setting. Mechanical and electrical engineering
(1) 51.01 - module type, this parameter is shown by the transmission device to detect the module type. Its parameter value users can not adjust. If this parameter is not defined, communication can not be established between the module and the drive.
(2) 51.02 - this parameter selects a communication protocol, "0" for the selection of the Profibus-DP protocol.
(3) 51.03 - this parameter is a PPO type for Profibus connection selection, "3" for PPO4, but the PPO type on the inverter should be consistent with the PPO type PLC.
(4) 51.04 - this parameter is used to define the device address number, that is, the address of the inverter's site, and each device in the Profibus connection path must have a separate address. The design of the two sets of 2, 3, respectively.
4.2 connection parameter
The process parameters are connected with the definition and connection of the corresponding parameters of the NPBA-12 dual port RAM connector and the inverter, which includes two parts: the main station (PLC) to the inverter and the inverter to the main station (PLC). Set the following connection parameters on the frequency converter. (1) the PZD value of the PLC value from the transmission to the transmission device
PZD1 L - control word, such as the start of the inverter to enable, stop, stop, and other control commands;
Frequency setting of PZD2 L - frequency converter.
(2) the PZD value of the transmission from the transmission device to the PLC
PZD1 L - status word, such as alarm, fault and so on inverter operation state;
PZD2 L - the actual value of the speed of the inverter, current actual value, etc.. Mechanical and electrical professional technical network
5 concluding remarks
The inverter control system adopts the Profibus-DP field bus control mode, not only the whole system reliability is strong, the operation is simple.