Application of GPRS Communication in Water Supply Pipeline Network Remote Monitoring System

Part 1 Overview (Excerpt)

In view of the fact that there are many monitoring points in water supply networks, a wide distribution, and limited investment in technological transformation, the DS207A wireless remote measurement and control terminal (GPRS-RTU) introduced by Xiamen Yaowang Electronic Technology Co., Ltd. provides a water supply company with a wireless network communication based on GPRS. Sets high-performance data acquisition, real-time storage of large-capacity measurement and control data, high-stability communication transmission and real-time control as one of the cost-effective water supply pipe network real-time monitoring solutions.

Part II Comparison of several pipeline network monitoring point construction plans

In recent years, the application of GPRS communication as a networking method for the construction of a remote monitoring system for water supply pipe networks has gradually become popular. In the construction of monitoring points, early projects often use the "sensor, field instrument + PLC + DTU", or "sensor, field instrument + RTU + DTU" solution, as shown below:

The above two types of monitoring and control point solutions have large system scale and high cost, and have a long construction period and high maintenance cost. And, because the data collection and network communication are carried by two independent devices, and most of them do not have the function of on-site data storage, resulting in low data security at the monitoring point (when the GPRS network communication fails, data collection is lost), and the application is flexible. Weak (different communication protocols, speeds, formats, RS485 interface meters, to be applied at the same time, high difficulty) are not ideal.

The DS207A remote measurement and control terminal launched by Xiamen Telescope Electronic Technology Co., Ltd. (IOTtek) can perfectly solve such defects and is a cost-effective solution.

1. Precise and integrated design: local measurement and control data acquisition, large-capacity record storage, and GPRS/SMS data communication integration, providing customers with cost-effective solutions.

2, basic monitoring and control port configuration: 4 analog signal input, 4 switch / pulse signal input, 2 relay contact output.

3, high-precision analog measurement: 1 analog channel equipped with high-quality DS 16-bit ADC, embedded hardware digital filtering, with excellent anti-jamming characteristics.

2 analog channels can access 0-10V, 0-5V, 4-20mA and other standard sensor output signals.
3 Each channel has undergone rigorous aging and precision calibration to ensure that the measurement accuracy is within a highly reliable 0.1% range.
4 Ensure that the user's measurement accuracy is not lost in the transmission link, far less than the low-end 10-bit/12-bit SAR ADC scheme.

4, the switch channel can be connected to the pulse: support 1 switch off contact input 2 high and low input 3 count pulse input.

5, relay control output: 1 set of normally open contacts, a set of common, normally open, normally closed contacts.

2 The relay does not need to maintain current for a long time.

3 Relay contacts support de-energized contact state hold.

4 Relay outputs can be associated with alarm events.

6, port detection alarm recognition: support for 1 analog channel high and low alarm 2 switch channel trigger alarm 3 support analog channel, pulse count channel change rate alarm.

7, data center flexible configuration: support 1 always online 2 regular online 3 SMS control online.

Data center main functions: support 1 data acquisition and control 2 remote control 3 storage record access

4 remote setting parameters 5 alarm information processing 6GSM network information query

8, reliable GPRS communication: support 1 fixed IP / domain name resolution access 2 support TCP / UDP data protocol 3 automatic heartbeat packet technology.

4 Fully tested and optimized communication fault tolerance mechanisms to ensure that RTUs can accurately and timely communicate with the data center.

9. Main functions of SMS communication: 1 The alarm message that supports editable content is sent to the preset mobile phone number.

2 Support SMS inbound query and set data center parameters, SMS control login data center.

2 48 groups of scheduled RS485 timing access data can be preset, and the communication results are automatically stored and reported.

3User configurable RS485 communication latency parameters, and failure retransmission mechanism.

4 Support RS485 communication access triggered by alarm event correlation.

11, measurement and control record storage management: 1 storage capacity of up to 30,000 records, including: analog / switch channel measurement records, RS485 interface timing communication records, alarm event records.

2 Support data center flexible query management of various types of storage records.

12, a balanced low-power design: 1 for the field of small solar power supply environment design, the average current consumption of 60mA (conventional networking, communication standby).

2 It is equipped with a high-quality holding relay. The relay pulls in for a long time and does not need to maintain the current to save power.

Part IV Application Diagram of DS207A Remote Measurement and Control Terminal in Water Supply Pipeline Monitoring System

4.1 Water Supply Pipeline Monitoring Point Description: (as illustrated above)

The hydraulic data monitoring project of the water supply pipeline is mainly the pipeline pressure and the water flow, and the electromagnetic water meter can also be installed where large user metering and regional metrology (DMA) are required.

压力 Pressure measurement can select sensor with 4-20mA or 0-10V standard current/voltage signal output type.

管道 Ultrasonic flow meters (RS485 communication interface using Modbus-RTU/Modbus-ASCII protocol) can be used for measuring the flow of water in pipelines.

RS The RS485 communication interface of the electromagnetic water meter uses the CJ/T188 protocol.

⊙ According to the needs of the site, other measurement signals can be installed and accessed.

These live signals can be directly connected to the DS207A remote measurement and control terminal. After the DS207A is powered on, it will establish a communication connection with the data center through the GPRS network. At the same time, according to the set data collection interval, the DS207A will perform accurate measurement and communication access for the connected operational sensors and instruments, and store and record the data, and then send this data to the data center in real time. The data center can also call in real-time to measure the operating parameters of the water supply pipeline and quickly query the DS207A's pipeline data storage records.

The DS207A uses a rigorous and reliable communication and control design to ensure that it achieves a high level of data security. After the communication failure with the data center occurs due to external factors (such as mobile network failure, SIM card arrears), local data collection and storage are not affected. When the fault is removed, the DS207A can quickly re-establish connection with the data center and resume communication. In addition, the on-site operation data during the communication fault can be obtained through the center's quick query. This mechanism ensures that the user's data integrity and security are guaranteed.

DS207A has accurate measurement quality. A 16-bit DS ADC is used internally to provide high immunity to interference, allowing measurement quality to reach a highly reliable 0.1% level accuracy. This ensures that the user's system data acquisition accuracy is not lost in the transmission link.

DS207A has a perfect monitoring mechanism. In addition to setting the upper and lower limit alarms of conventional analog channels, it can also effectively identify the analog channel change rate alarms. This design offers the possibility to predict and find the burst of the water supply pipeline in the fastest time possible. For example, the user can set a reasonable range (kpa/min) for the rate of change of the pipeline pressure. The DS207A will monitor the pipeline pressure change trend based on a user-defined threshold. When the pipeline pressure is found to rise sharply or drop sharply, an alarm message will be sent to the data center to facilitate the system's early warning and decision-making.

The DS207A uses the SMS message channel as an auxiliary means of communication to support the sending of alarm messages to administrators and to support SMS inbound calls for various queries and controls.

4.2 Description of monitoring points for water wells: (as illustrated above)

In northern China, in addition to river water sources, water wells are commonly used as water sources. The data monitoring projects of water source wells mainly include the water level of the water source wells, the operating parameters of the water pump motor, and the pressure of the water pipelines and the water flow, etc. The water source well water quality measuring instruments can also be installed in areas with good economic development conditions.

⊙ Water level measurement of water source wells can choose input level gauge (4-20mA standard current output)

⊙ DS207A relay output interface can be connected to the water well pump motor control cabinet, remote control of the motor start and stop.

运行 The operating parameters of the water source pump motor can be converted into 4-20mA signals by three-phase AC voltage/current transducers, and the DS207A can be connected to monitor the running status of the motor.

电能 An electric energy meter with RS485 communication interface (DL/T645 protocol) can be installed at the water source well pump station to realize real-time monitoring of the power consumption of the pump station.

输 Water pressure measurement can choose sensor with 4-20mA or 0-10V standard current/voltage signal output type.

输 Ultrasonic flowmeter (RS485 communication interface using Modbus-RTU/Modbus-ASCII protocol) can be used for flow measurement.

RS The RS485 communication interface of the electromagnetic water meter uses the CJ/T188 protocol.

⊙ According to the needs of the site, other measurement signals can be installed and accessed.

These live signals can be directly connected to the DS207A remote measurement and control terminal. The main functions of the DS207A in the water source well are similar to those in section 4.1 (supply pipeline monitoring point), and will not be repeated here.

DS207A uses a flexible RS485 communication interface design. RS485 interface instruments that support different communication protocols, different communication rates, and different byte formats (check and stop bits) can be accessed at the same time. At the monitoring site of the water source well, the user may need to perform data communication on various measuring instruments such as DL/T645 meter protocol, CJ/T188 water meter protocol, Modbus-RTU flowmeter protocol, and other types of protocols. The DS207A's RS485 free-access design perfectly meets the needs of users.

The DS207A can set up 6 groups of timed RS485 communications, and each group can set up to 8 different access data. When the scheduled access time arrives, the DS207A will actively access the corresponding meter. In addition, the communication results are stored and recorded, and the communication results are reported to the data center. For different types of instruments from different manufacturers, the response characteristics on the RS485 communication interface are not completely consistent. The DS207A can ensure the reliable implementation of various types of communication time interval parameters and RS485 communication retransmission mechanism. Instrumentation communication. The application of these measures ensures the integrity of the system data.

4.3 Construction of Data Monitoring Center

Access to the data center: The data center uses ADSL to connect to the Internet and adopts public network fixed IP or public network dynamic IP+ domain name resolution to accept communication from the public network monitoring and control terminal. DS207A supports fixed IP and domain name resolution in two ways to connect with the data center. For applications where system security and stability are more demanding, users can apply to the China Mobile GPRS service for a special network APN. The SIM card uses a private network APN to access the data center. The mobile company connects the data center server with a dedicated line. Users can choose the access method that meets the needs of the project according to the scale of the project construction, investment conditions and other factors.

Data center software can be built using B/S structure or B/S+C/S structure. Realize various functions such as real-time data reception, display, statistical analysis, curve generation, report generation, early warning and decision-making, and data backup for the operation data of each pipe network monitoring point and water source well monitoring point.

Xiamen Yaowang Electronic Technology Co., Ltd. provides the following support for user system application software development:

⊙ Provide "DS207A Data Center Test Software" and "DS207A Parameter Setting Software" for communication connection and terminal performance testing for users in the early stage of project construction.

Establish a convenient test platform at the stage. The software can fully test the various functions of the terminal, and has data acquisition curve fitting, recording and other functions. Convenient for users

The system function performs a complete functional assessment and indicator testing.

⊙ Provides DLLs based on Delphi7. Users can quickly implement communication layer services of system application software by calling functions.

We also provide demonstration source code based on C# and Delphi platforms.

The fifth part uses DS207A to carry out the outstanding advantage of the construction of the water supply network monitoring system