one. system design
In the automatic control project of a factory, two Siemens S7-300 control system equipments that are separated by 3 km are required to exchange data. Because of the distance between the two devices, and the separation of mountains, the use of Ethernet fiber optic transmission is not realistic, given BANNER's excellent ultra-long-range wireless sensor products, designed to use the Data Radio radio DX80DR2M in its surecross series. At the same time, since the two S7-300 control systems are all CPU315-2PN/DP controllers with Profibus-DP master interface, and the radio station DX80DR2M supports RS485 Modbus RTU protocol, we design the NT30-DPS gateway (ModbusRTU to Profibus-DP slave) to achieve data exchange, the system structure is designed as follows:
two. Functional description
As shown in Figure 1, the NT30-DPS of both remote stations are connected to the Profibus-DP bus of the CPU315-2PN/DP via their Profibus-DP interface as DP slaves, and their RS485 output lines are connected to the DX80DR2M radio. In order to realize master-slave data exchange of Modbus RTU, one of the NT30-DPSs is designed to operate as a Modbus RTU master and the other NT30-DPS is designed to operate as a Modbus RTU slave. When the system is running, the Modbus RTU master gateway automatically reads and writes the register data of the Modbus RTU slave gateway according to the pre-configured communication command table (ModbusRTU commands FC1-FC16), and then each gateway passes through the Profibus-DP input and output image area and the respective The CPU315-2PN/DP master station realizes the data exchange, thus realizes the data exchange between CPU315-2PN/DP, the realization of the data exchange is as follows:
As shown in the above figure, two NT30-DPS and their respective CPU315-2PN/DP realize 64 bytes of input and output data exchange. The communication mechanism is as follows:
1. The output data QW0-QW62 from the right CPU 315-2PN/DP is automatically transferred to the input register of the NT30-DPS as a Modbus RTU slave via the Profibus-DP mechanism, and then passed by the NT30-DPS as the Modbus RTU master station. The FC4 function number is read into the input register Register 1-32, and is finally transferred to the IW0-IW62 input image area of ​​the CPU 315-2PN/DP on the left side through the Profibus-DP mechanism, thereby realizing the output data of the right CPU. Transfer of input data of the left CPU.
2. The output data QW0-QW62 from the left CPU 315-2PN/DP is automatically transferred to the output register Register 1-32 of the NT30-DPS which is the Modbus RTU master via the Profibus-DP mechanism, and then writes data to the output via function number 16. The holding register of the NT30-DPS, which is a Modbus RTU slave, is automatically transferred to the IW0-IW62 input image area of ​​the right CPU 315-2PN/DP through the Profibus-DP mechanism, thereby realizing the output of the left CPU. Transfer of data to the right CPU input data.
As mentioned above, the data exchange between the CPU315-2PN/DP and the gateway is performed automatically by the Profibus-DP mechanism, and the data transfer between the two gateways as the master and the slave of the Modbus RTU is preset via the configuration command of the master station. Therefore, for the CPU315-2PN/DP at both ends, the entire data exchange is realized without writing any program.
three. NT30-DPS parameter configuration
The parameter configuration of NT30-DPS is realized by Hirschson SYCON.net software. The configuration parameters of NT30-DPS as Modbus RTU master station are as follows:
1. MODBUS table
Interface and RTS RS485 RTS ON
Baudrate 19200 Bits/s
Stopbits 1
Parity none
Mode Master / address
Modbus address 1
2. MODULES table
In byte con 64
Out byte con 64
3. COMMAND table
Slave Function Address Quantity Register .Coil Write
2 4 30001 32 1 0 Cycle
2 16 40001 32 1 0 Cycle
4. SUPERVIS table
Supervision Mode SlaveError
The parameters not listed above use the default parameters.
For the NT30-DPS as a Modbus RTU slave, the configuration parameters are as follows:
1. MODBUS table
Interface and RTS RS485 RTS ON
Baudrate 19200 Bits/s
Stopbits 1
Parity none
Mode Slave / address
Modbus address 2
2. MODULES table
In byte con 64
Out byte con 64
3. COMMAND table
No command
The parameters not listed above use the default parameters.
be careful:
1. No matter master-slave station should use ModbusRTU standard address format, ie address;
2. The MODULES address allocation space of the master and slave must be the same, the above is allocated 64 bytes of input and 64 bytes of output;
3. For the master station, its Supervision Mode parameter cannot be selected off, otherwise if a slave station in the multi-slave network communication fails (such as disconnected from the network), then the master gateway will not automatically skip the failed slave ( Always try to communicate with the failed slave until it resumes communication);
four. Configuration in STEP7
To connect the NT30-DPS to the Profibus-DP network of the CPU315-2PN/DP you must configure the network hardware in the Siemens STEP7 software. First of all, in order to be able to find the NT30-DPS gateway in the STEP 7 Hardware Catalog, the NT30-DPS GSD file must be installed:
1. Insert the random CD of NT30-DPS gateway into the CD-ROM drive;
2. Close all the current projects in the STEP7 Hardware window, and then select the menu Options-> Install GSD File, in the pop-up dialog box, select the GSD file on the CD (in GSD \ PROFIBUS directory), and finally click the Install button;
After installing the GSD file, you can configure the slave of Profibus: Open the Hardware window of the STEP7 project, select the NT30-DPS gateway (under PROFIBUS-DP\Additional Field Devices\Gateway) from the catalog on the right, and drag it to the left CPU. Profibus finally sets the Profibus address and input/output image area of ​​the NT30-DPS.
The hardware configuration of STEP7 is as shown below (using CPU313C-2DP):
Fives. Application notes
1. The NT5-DPS has a +5 VDC power supply in the RS485 pinout. Therefore, there should be no short circuit between the pink line and grey line (P and N of the RS485 and yellow line (ground line), otherwise it will affect the communication and even burn Bad communication port, please refer to the hardware manual in the CD box.
2. If the NT30-DPS STA indicator lights up, the NT30-DPS has established a connection with the Profibus-DP master;
3. After modifying the Profibus address of the NT30-DPS (set via the address code on the NT30-DPS), it is necessary to power on again;
4. Newly-manufactured NT30-DPS need to be downloaded before use (downloaded in SYCON.net software);
six. Conclusion
Hirsch Automation Systems GmbH is an expert in the field of global industrial network communications. In addition to a wide range of protocol conversion gateway products, it also provides computer communication boards CIF, embedded communication modules COM and the world's most advanced The network communication protocol chip netX, Wuxi Beichen Automation Technology Co., Ltd. is the distributor of Germany Hilscher in East China, we are willing to provide the optimal solution for any network communication project in the field of industrial automation. This case was supported by the technicians of Shanghai BANNER Company and Shanghai Hiveson Office during the debugging, and expressed thanks.