Abstract: This paper wastewater treatment systems, when companies with interest a new generation of small integrated PLC, proposes a new central control room and the water tank on site communications solutions between devices, that the sewage pond and between the central control room Handset program. Currently the system has been successfully applied to wastewater treatment site, and has good cost performance.
Key words: wireless communications, sewage treatment, DP network
Abstract: Aimed at sewage dispose system, a new method to solve the communication problem between central control office and locale equipment in sewage pool based on HOLLiAS-LEC G3 PLC, ie, a wireless communication method between central control office and sewage pool is put forward in the thesis. The system was used successfully in locale sewage dispose system and the ratio of cost and performance of the system is satisfied.
Keyword: Wireless communication, Sewage disposal, Profibus-DP network
1 Introduction China s rapid economic development and rising levels of urbanization, industrial wastewater and domestic sewage is increasing. In order to maintain sustained, healthy growth and ecological and environmental cycle, industrial and domestic sewage must be addressed. At present, China s economically developed areas in major cities and towns of all sizes have been built a sewage treatment plant, but most underdeveloped counties cities and small towns do not take all types of sewage treatment measures, directly into nearby rivers. Environmental protection requirements continue to increase sewage treatment measures are not taken to a small town the next several years will inevitably build sewage treatment plants. A wide range of large towns, the sewage treatment facilities in great demand. At the same time, by the investment restrictions, these sewage treatment plants are more willing to use economic and practical product. This paper introduces monitoring system to meet the sewage treatment equipment safe and efficient operation also has a very good value for money, with good economic, social and promotion prospects.
2 of the original program of sewage treatment plant, sewage treatment facilities all the more dispersed distribution. Field devices to monitor operating parameters and operating conditions, need to establish a central monitoring system. The monitoring system consists of on-site inspection,B7 from the long, good reliability, strong anti-interference, save cable, maintenance and low cost.
3 design shown in Figure 2, uses and benefits of the program when the company s small integrated PLCCPU module LM3107 data collection and transmission. LM3107 its own communication interface RS232, RS232 connection to the antenna, the antenna used Modbus protocol with CRC check, the agreement is simple, reliable. Antenna, can achieve long-distance wireless communication Modbus to achieve for each water pool (Modbus Slave) data with the host (Modbus master station) data exchange. Then, Modbus master and then DP communication module access to DP, so that you can achieve all field devices (Modbus slave) and the Central Control Room (DP master) data exchange between the completion of data acquisition and control.
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Figure 3 shows the data flow diagram, are two-way communication between each module. Sewage Pond collection up data, analog analog input module LM3310 input to the next bit LM3107 module (Modbus slave), digital direct input bit LM3107 module (Modbus slave), the upper with a LM3107CPU module with a LM3401DP from the station module connected to the DP network.
Inferior LM3107RS232 and wireless communication modules as a Modbus slave, upper LM3107RS232 and wireless communication modules as a Modbus master. LM3107 module supports the standard Modbus RTU protocol, between the upper and lower bit LM3107 using Modbus communications. Re LM3401DP upper LM3107 module from the station central control room for data exchange.
Wireless communication can actually Modbus communication parameters to choose are as follows:
Check: odd parity, even parity, no check digit: 7, 8-bit Baud Rate: 300bps, 600bps, 1200bps, 2400bps, 4800bps, 9600bps, 19200bps, 38400bps
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4 advantage of this program a solutionHas the following advantages:
1. only need a DP line can collect all the sewage pool data to the central control room DP master station, compared with traditional communications programs to save a lot of communication cable, but also reduces the cable construction Gong Zuoliang improved system reliability and maintainability.
2. using wireless communication, long distance data transmission, data transmission through the use of antennas, transmission distance and antenna related, up to 5K meters.
3. using LM3107 can achieve up to 247 Modbus slave connected, saving each cesspool DP slave module costs, instead of each water pool as a Modbus slave existence, only one DP slave can the realization of all the sewage pool data center monitoring station data exchange.
5 Concluding remarks while commissioning and trial operation, the HOLLiAS-LEC G3 Series PLC as the control system of small integrated wireless surveillance program have been successfully applied to wastewater treatment site. Proved, the lower the overall cost of the design program, data, long transport distance reliability, anti-interference ability, and maintenance cost is lower with high maneuverability, the market, with Jiangyou Li and competition power, sewage treatment industry added Le Yi Tao perfect solution.
References
[1] HOLLiAS-LEC G3 small integrated PLC hardware manual. Hangzhou and Belgium Automation Co., Ltd.
[2] HOLLiAS-LEC G3 small integrated PLC software manual. Hangzhou and Belgium Automation Co., Ltd.