With the development of the economy, China will be one of the regions with the fastest growth in global refining and petrochemical production capacity, and will soon become the world’s largest petrochemical market. At present, due to the difficulty in meeting the needs of market economy and social development in the domestic petrochemical industry, the main contradiction has shifted from insufficient overall quantity in the past to a coexistence of insufficient overall quantity and quality. Over time, the contradiction of insufficient quality will gradually rise to the main contradiction (as evidenced by the foggy weather in Beijing). Therefore, structural adjustment is an important task for Sinopec at present. Therefore, the restructuring of petrochemical enterprises must accelerate the pace of technological transformation. The construction of ethylene projects should follow the trend of existing automation technology development as much as possible, using mainstream control systems to save construction investment and shorten construction cycles.
The development of the petrochemical industry in today’s world is trending towards large-scale, base based, and integrated refining, with an increasing concentration of industries. DCS systems have been widely used in the chemical industry due to their excellent performance. In the chemical industry, the detection and control of temperature, pressure, flow rate, and liquid level account for the vast majority; In addition, in the operation of large process equipment such as towers, kettles, and tanks, it is essential to detect and control the switching values of various mechanical and electrical equipment such as fans, pumps, and valves. However, the communication protocols of these devices may differ from those of DCS systems. To solve this problem, we need to use a protocol conversion gateway.
This article will introduce practical application cases of this protocol conversion gateway.
abstract
In a large ethylene project in Northeast China, the main control network uses MODBUS protocol, while the remote on-site equipment uses PROFIBUS-DP protocol. At this time, it is necessary to transmit the signal of the on-site equipment to the main control network for monitoring, and achieve communication between the two different protocols. This project requires the DCS system to monitor the Siemens G150 frequency converter and Siemens MM440 frequency converter on the workshop production line. However, these frequency converters that control the motors use the PROFIBUS-DP protocol. This requires a module for converting from PROFIBUS to MODBUS protocol, which can be achieved by the PBM-G-MBS in Dingshi’s main station gateway series.
Beijing Dingshi Innovation Technology Co., Ltd. is composed of the technical backbone of the China Fieldbus PROFIBUS Technology Qualification Center (CPCC). It is a high-tech enterprise recognized by the Beijing Municipal Science and Technology Commission. It has pioneered the concept of “bus bridge” in the Chinese automation industry, developed various PROFIBUS bus bridge products, and actively promoted engineering applications, and has won the trust of a large number of customers.
Solution
1. System architecture and layout
The Dingshi PBM-G-MBS master gateway plays a role in connecting MODBUS and PROFIBUS protocols, serving as the master station on the PROFIBUS side and the slave station on the MODBUS side. A certain DCS control system is the main station on the MODBUS side. Siemens frequency converter is a slave station on the PROFIBUS side.
In this system, a certain DCS system needs to monitor Siemens MM440 and G150 frequency converters. The schematic diagram of its control system is shown below
2. System implementation functions
In this system, the frequency converter transmits its data (voltage, power, frequency, etc.) to the main station gateway PBM-G-MBS through PROFIBUS-DP, and then the DCS system obtains the data of the frequency converter from the main station gateway through the MODBUS interface; Similarly, the DCS system also needs to send commands to the frequency converter through the MODBUS interface → main station gateway → PROFIBUS-DP, in order to control the start stop and action of the frequency converter.
3. Configuration and application of the main station gateway
Due to the fact that the main gateway here serves as the PROFIBUS master, in order to connect to the following PROFIBUS slave stations (Siemens MM440 and G150 frequency converter), configuration software is required to parse the GSD files of the slave stations. Dingshi’s configuration software PB Confi can achieve such functions. For specific usage methods, please refer to the “PBM-G-MBS Product Manual” on the download section of Dingshi Company’s website. As the main gateway here is the PROFIBUS master station, to connect to the following PROFIBUS slave stations, configuration software is needed to parse the GSD files of the slave stations. Dingshi’s configuration software PB Confi can achieve this function. The Modbus to Profibus DP gateway PB-G-MBS serves as a Modbus slave station on the Modbus side and a master station on the Profibus DP side, establishing communication between the Profibus DP slave station (Siemens frequency converter) and the Modbus master station. The DCS communication part adopts a Modbus communication module and is equipped with a Modbus communication software package. The maximum communication data capacity of this communication module is 4000 words. Through Beijing Dingshi Main Station Gateway PB-G_ The MBS gateway configuration software PB Confi performs relevant configuration on PB-G-MBS, converting and storing DCS read and write instructions and data accordingly. The data transmission process is shown in the following figure (taking the frequency converter as an example)