Tap water flow acquisition system

Abstract

The utility model relates to the technical field of tap water treatment, and particularly discloses a tap water flow acquisition system which is stable in signal transmission, capable of simultaneously acquiring instantaneous flow and accumulated flow of water and low in hardware cost. The tap water flow acquisition system comprises an HART (Highway Addressable Remote Transducer) conversion module, a power supply module, one or more flowmeters, a terminal resistor and a PLC (Programmable Logic Controller), wherein the HART conversion module is used for converting an analog quantity signal into an RS485 signal; the power supply module is electrically connected with the HART conversion module; the one or more flowmeters are electrically connected with the HART conversion module;

Description

Technical Field

[0001] The utility model relates to the technical field of tap water treatment, in particular to a tap water flow collection system. Background Art

[0002] In the daily production and operation activities of the water plant, flow measurement can not only reflect the water intake and supply conditions, but also provide a basis for the diagnosis of various indicators in the water treatment system, so as to effectively carry out tap water production operations and dosing control. With the continuous improvement of the automation level of the water plant, as an important instrument for data measurement, the accuracy and stability of flow meter data acquisition are of great significance to the normal operation of the water plant. Traditional flow meters on the market usually use 4-20mA output signals as feedback signals for flow meter data, and transmit the feedback signals to the PLC controller of the water plant control system in the form of analog signals. Since the 4-20mA current signal collected by the analog quantity is easily disturbed by the on-site environment during transmission, the flow signal collected by the PLC controller is not stable and reliable enough. Furthermore, when the traditional flow meter uses analog quantity to collect data, it cannot take into account the collection of instantaneous and cumulative quantities of the flow meter at the same time. It can only selectively read one of the instantaneous flow and cumulative flow, which is difficult to meet the data needs of smart water services. In addition, although some flow meters on the market have communication functions that can achieve long-distance and stable data transmission, the price of such instruments with communication functions is usually more expensive than that of instruments with 4-20mA output, which will increase the hardware cost of the water plant. Utility Model Content

[0003] Based on this, it is necessary to provide a tap water flow collection system with stable signal transmission, which can simultaneously collect the instantaneous flow and cumulative flow of water and has low hardware cost to address the above shortcomings.

[0004] A tap water flow acquisition system comprises a HART conversion module for converting an analog signal into an RS485 signal, a power supply module electrically connected to the HART conversion module, one or more flow meters electrically connected to the HART conversion module, a terminal resistor electrically connected to the HART conversion module, and a PLC controller, wherein a communication port of the PLC controller is communicatively connected to a signal output end of the HART conversion module.

[0005] In one embodiment, the power supply module is a 24V DC power supply.

[0006] In one embodiment, when the number of flow meters is greater than one, the flow meters are connected in parallel, and the terminal resistor is connected to the signal input tail end of the HART conversion module.

[0007] In one embodiment, the resistance of the terminal resistor is 250Ω.

[0008] In one embodiment, the HART conversion module includes a HART communication receiver used as a signal input end of the HART conversion module and collecting flow meter signals, a HART protocol parser electrically connected to the HART communication receiver, a data storage device electrically connected to the HART protocol, and a protocol converter electrically connected to the data storage device and used to convert the HART protocol into a MODBUS RTU protocol. The protocol converter transmits the RS485 signal to the PLC controller via the MODBUS RTU protocol.

[0009] In implementing the tap water flow collection system of the utility model, a HART conversion module is set between the flow meter and the PLC controller. The HART conversion module converts the analog signal collected by the flow meter into an RS485 signal under the MODBUS RTU protocol, and further transmits the collected flow information of the tap water system to the remote PLC controller by wireless signal transmission. The RS485 signal transmission under the MODBUS RTU protocol is stable, which ensures the stability and reliability of the flow signal collected by the PLC controller and improves the accuracy of data collection in the water plant. After conversion by the HART conversion module, the instantaneous and cumulative quantities of the flow meter can be collected, which can meet the needs of smart water services for multiple types of data. Multiple flow meters can transmit signals to the PLC controller over long distances through a HART conversion module. Compared with a single flow meter with communication function, the flow collection system of this solution has lower cost and reduces the hardware cost of the water plant. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a module structure diagram of a tap water flow collection system in one embodiment of the utility model;

[0011] Figure 2 This is a wiring diagram of a tap water flow collection system in one embodiment of the utility model;

[0012] Figure 3 This is the data curve collected by 4 to 20 mA signal;

[0013] Figure 4 A data curve collected by a tap water flow collection system in one embodiment of the utility model;

[0014] Figure 5 This is a curve for simultaneously collecting instantaneous flow and cumulative flow data in one embodiment of the utility model. DETAILED DESCRIPTION

[0015] In order to make the above-mentioned purposes, features and advantages of the utility model more obvious and easy to understand, the specific implementation methods of the utility model are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the utility model. However, the utility model can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the utility model, so the utility model is not limited by the specific embodiments disclosed below.

[0016] Please combine Figure 1 and Figure 2 The utility model discloses a tap water flow collection system with stable signal transmission, which can simultaneously collect the instantaneous flow and cumulative flow of water and has low hardware cost. The tap water flow collection system includes a HART conversion module 100 for converting analog signals into RS485 signals, a power module 200 electrically connected to the HART conversion module 100, one or more flow meters 300 electrically connected to the HART conversion module 100, a terminal resistor electrically connected to the HART conversion module 100, and a PLC controller 400. The communication port of the PLC controller 400 is communicatively connected to the signal output end of the HART conversion module 100. The terminal resistor is used to reduce the signal waveform distortion problem caused by signal reflection during the transmission of the analog signal collected by the flow meter 300 to the HART conversion module 100, so as to improve the reliability of signal transmission. According to the different impedances of the transmission cable, the resistance value of the terminal resistor is 110Ω-330Ω. Preferably, in this embodiment, the resistance value of the terminal resistor is 250Ω.

[0017] During the liquid flow collection process of the water plant management system (including the flow collection of water and chemicals during the treatment process and the collection of water intake and supply flow after treatment), the flow meter 300 collects the instantaneous flow signal of the liquid in the pipeline, and sends the instantaneous flow signal in the form of analog data to the HART conversion module 100. When powered by the power module 200, the HART conversion module 100 converts the protocol of the received analog data to convert the analog data based on the HART protocol into an RS485 signal based on the MODBUS RTU protocol, so that the converted flow RS485 signal can be further remotely transmitted to the PLC controller 400 via wireless communication, thereby realizing remote transmission of the data collected by the flow meter 300. In addition, in the process of the HART conversion module 100 performing protocol conversion on the analog signal, since the analog signal is converted into an RS485 signal, the RS485 signal based on the MODBUS RTU protocol can read multiple data at the same time. In this way, after the flow meter collects the flow data, it can simultaneously transmit the instantaneous flow and the cumulative flow data to the PLC controller via the HART conversion module 100, thereby realizing the simultaneous collection of instantaneous flow and cumulative flow.

[0018] In the above-mentioned tap water flow collection system, a HART conversion module 100 is set between the 4-20mA output signal output by the flow meter 300 and the PLC controller 400 to convert the data into an RS485 signal that can be used for data collection through the Modbus RTU protocol, and further transmit the collected flow information of the tap water system to the remote PLC controller 400 through wireless signal transmission. The RS485 signal transmission under the MODBUS RTU protocol is stable, which ensures the stability and reliability of the flow signal collected by the PLC controller 400 and improves the accuracy of data collection in the water plant. The instantaneous flow and the cumulative flow can be collected simultaneously without replacing the flow meter 300. While meeting the needs of smart water services for multiple types of data, multiple flow meters 300 can transmit signals to the PLC controller 400 over long distances through a HART conversion module 100. Compared with a single flow meter 300 with communication function, the flow collection system of this solution has lower cost, which reduces the hardware cost of the water plant. During long-distance transmission, RS485 signals are used to replace analog signals to reduce data instability problems caused by analog signals. The system runs more stably and reliably, and can better meet the construction needs of current automated and intelligent water plants.

[0019] In this embodiment, the power module 200 is a 24V DC power supply, which is used to provide a 24V low voltage DC voltage for the normal operation of the HART conversion module 100. When the number of flow meters 300 is greater than one, each flow meter 300 is connected in parallel, and a terminal resistor is connected to the signal input tail end of the HART conversion module 100. In this embodiment, 3-4 flow meters 300 can be connected in parallel to the same HART conversion module 100. Taking a DN20 electromagnetic flow meter 300 as an example, its price is about 15,000-20,000 yuan. For a water plant with a production capacity of 200,000 tons / day, its entire management system uses about 20-30 flow meters 300. When 3-4 flow meters 300 are connected in parallel to a HART conversion module 100, the market price of a HART conversion module 100 is about 500 yuan. The flow meter 300 is calculated at a price of 15,000 yuan each. Using the HART conversion module 100 to convert instead of replacing the flow meter 300 can save 15000x30-(500x10)=445,000 yuan, which significantly saves the hardware cost of the water plant.

[0020] In one embodiment, the HART conversion module 100 includes a HART communication receiver used as a signal input terminal of the HART conversion module 100 and collecting signals from the flow meter 300, a HART protocol parser electrically connected to the HART communication receiver, a data storage device electrically connected to the HART protocol, and a protocol converter electrically connected to the data storage device and used to convert the HART protocol into a MODBUS RTU protocol, and the protocol converter transmits the RS485 signal to the PLC controller via the MODBUS RTU protocol. The HART communication receiver receives data transmitted based on the HART protocol. The HART communication protocol adopts the principle of frequency shift keying, which is based on the Bell 202 communication standard. The digital signal is represented by two frequencies: 1200Hz represents logic "1" and 2200Hz represents logic "0". Since the average component of the frequency signal is zero during communication, it will not affect the transmission of the analog signal. The sine waves of the two frequency signals are superimposed on the DC 4-20mA analog signal and transmitted simultaneously. Not only can the superimposed DC 4-20mA analog signal be used, but also the same cable can be used to realize two-way multi-information transmission with digital signals. The HART protocol parser is used to parse the signal transmitted via the HART protocol to obtain the instantaneous flow data and cumulative flow data of the flow meter 300. The HART protocol converter is used to convert the protocol and transmit the converted MODBUS RTU protocol data to the PLC controller. Furthermore, the HART protocol converter is provided with a data output structure for communication connection with the communication port of the PLC controller 400. The HART protocol converter and the PLC controller 400 perform data transmission based on the MODBUS RTU protocol to achieve long-distance and stable transmission of the flow signal.

[0021] After receiving the processed 4-20mA flow simulation signal, the HART communication receiver transmits the flow simulation signal to the HART protocol parser. The HART protocol parser parses and splits the flow data transmitted by the HART communication receiver, and the protocol converter rearranges the data to form MODBUS RTU communication protocol data, and sends the new protocol data to the PLC controller 400 through the RS485 wiring method, thereby realizing the long-distance transmission of instantaneous flow data and cumulative flow data.

[0022] Before collecting tap water flow through the above system, the parameters of the PLC controller need to be set. Specifically, the parameters required for the PLC controller to read data need to be set, including baud rate, data bit, wiring method, data stop bit, parity bit, communication time, etc. The parameters must be consistent with the instrument end; the communication station address, data address and final data storage address corresponding to each flow meter are set on the PLC controller so that the PLC controller can receive the flow data transmitted by each flow meter through the HART conversion module.

[0023] Please combine Figure 3 and Figure 4 , in the same period, comparing the flow data collected by the traditional 4-20mA signal transmission flow meter with the flow data collected by this system, it is found that the fluctuation range of the data collected by the traditional 4-20mA signal is between 60 and 70 (such as Figure 3 As shown), the fluctuation range of the data collected by the system of this embodiment is within 10 (as shown Figure 4 As shown in the figure, it can be seen that the traffic data collected by the system of this solution is more stable and reliable. Figure 5 , by storing and sending data to the protocol converter through the data storage of the HART conversion module, the instantaneous flow and cumulative flow data can be collected simultaneously to meet the water data management needs of the water plant.

[0024] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0025] The above-mentioned embodiments only express several implementation methods of the utility model, and the description is relatively specific and detailed, but it cannot be understood as limiting the scope of the utility model patent. It should be pointed out that for ordinary technicians in this field, several modifications and improvements can be made without departing from the concept of the utility model, which all belong to the protection scope of the utility model. Therefore, the protection scope of the utility model patent shall be based on the attached claims.

Claims

1. A tap water flow collection system, characterized in that: It includes a HART conversion module for converting analog signals into RS485 signals, a power module electrically connected to the HART conversion module, one or more flow meters electrically connected to the HART conversion module, a terminal resistor electrically connected to the HART conversion module, and a PLC controller, wherein the communication port of the PLC controller is communicatively connected to the signal output end of the HART conversion module.

2. The tap water flow collection system according to claim 1, characterized in that: The power supply module is a 24V DC power supply.

3. The tap water flow collection system according to claim 1, characterized in that: When the number of flow meters is greater than one, the flow meters are connected in parallel, and the terminal resistor is connected to the signal input tail end of the HART conversion module.

4. The tap water flow collection system according to claim 1, characterized in that: The resistance of the terminal resistor is 250Ω.

5. The tap water flow collection system according to claim 1, characterized in that: The HART conversion module includes a HART communication receiver used as a signal input end of the HART conversion module and collecting flow meter signals, a HART protocol parser electrically connected to the HART communication receiver, a data storage device electrically connected to the HART protocol, and a protocol converter electrically connected to the data storage device and used to convert the HART protocol into a MODBUS RTU protocol. The protocol converter transmits the RS485 signal to the PLC controller via the MODBUS RTU protocol.

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