Wired Remote Water Meter

 

  

   

The Power-Free and Blind-Spot-Free Direct-reading Water Meter System is specifically designed and developed for the management of meter reading and billing for water companies.  It replaces the traditional water measurement technology of reed switch and pulse by the adoption of an innovative direct-reading method to collect water consumption data from the water meter’s mechanical wheel which guarantees metering data accuracy without electromechanical inconformity.

  

I.                    Description of the System

  

The main components of the system, as shown below, include a direct-reading resistance water meter, data concentrator, portable meter reading device, and an administration software system.

  

  

  

 

 Business Terminal

Payment Terminal

Manual Data Entry Terminal

Access Terminal for Portable Meter-Reading Device

 Printer

 Portable Device

 Wired

 Wireless

 Transmission

 Printer

Disk Array

Main Server

Backup Server

 Terminal

Water Company Management Center

 Router

Mobile PC

 Network

Meter Reading Station of Water Company

 Management

 Router

 Data Concentrator

 Meter Reading

Direct Reading Resistance Water Meters

 


Power-Free and Blind-Spot-Free

Direct-Reading Water Meter System


The power-free and blind-spot-free direct-reading meters are installed in the user’s piping to calculate water consumption, and this is done through the RS-485 wired remote data passage to transmit data from the meter to the concentrator.  The meters do NOT need power to operate as the water consumption can be measured by the mechanical part.  Power is only needed at the time of meter reading, which means that the concentrator supplies power to the meter when it reads data from the meter and sends out collection data command.  At this time, the direct-reading meter collects data from the mechanical number wheel, and the data collected from each meter is being sent back to the concentrator for storage.

After the concentrator has finished collecting data from the meters, it will cut its power supply to the meters, while the mechanical measurement of the meter remains in function.  By doing so, it can effectively reduce the meter’s power consumption and at the same time effectively reduce the cost of meters as it is not necessary to make provision for battery installation.

Based on the water company’s pre-determined servicing period, the water company’s meter reading stations can retrieve water consumption data stored in the concentrator through the portable meter-reading device.

When circumstances permit, one can use the portable device to collect data from the meters directly on-site, without the using concentrator, and therefore further reduces costs.

The water company should build a payment collection platform in local area network (LAN) for its meter-reading stations so that different terminals can perform different work according to different business requirements:  the portable access terminal exports data from the portable meter-reading device to the database, while the manual data entry terminal exports the manually collected readings on the mechanical meters into the database, thereby ensuring that the water consumption data of all the users are completely saved.  The business terminal takes care of account opening, account cancellation, information setting and modification, change of meters, and so on.  The payment collection terminal handles payment settlement as well as issuing and printing invoices, receipts and statistic reports.

When circumstances permit, the water company can build a wide area network (WAN) data collection platform and link up all the meter-reading stations through internet and set up a management center.  The management center is the core of the software platform of all the systems and all information of the users will be generated and saved here. 

The basic setting of the management software platform for data collection and payment collection is based on dual-server and disk array.  The disk array stores the basic information of all the users, their water consumption data and payment transaction history.  The server installs the operating system for metering and payment management.  Both primary and secondary servers are installed so that in times of failure, the secondary server can be used as backup to ensure real-time operation of the system at all times.

Data processed by the software platform will be stored and retained in the disk array in the management center.  Such setting can guarantee the relative independence of the different management software, and keeps interference arising from different business needs to the minimum.  At the same time it ensures data integrity and consistency and makes management such as inquiry handling and data analysis easy.

The works of data collection and payment collection are not done at the management center.   The terminals of the management center in water company is to manage and monitor enquiries, e.g. data search, data consolidation, analysis and reporting, for any business points.  Either desktop or mobile terminal can be used.  All terminals can generate and print statistical reports for different use. 


II.                  Structural Description

The power-free and blind-spot-free direct-reading water meters do not use the traditional reed switch and pulse technology but adopts a new metering processing method by making use of electronic devices to directly retrieve and verify meter readings from the mechanical number wheel and perform data communication through remote transmission passages.

The controlling system of the resistance water meters consists of CPU, motor-driver module, data collection module, data transmission module and power module.  The CUP controls all the modules and facilitates the meter to function.  The motor-driver module controls the data collection module and the touch and separation of mechanical meter’s wheel.  The data collection mould collects and determines the reading of wheel by resistance network and ascertains each reading value. The data transmission module exports the readings from the mechanical meter through the RS-485 data interface for the external device to complete the tasks of data collection and hence meter-reading.  The power module supplies power to all the modules and  acts as voltage stabilizer.  The following diagram explains how this works:

CPU

Data Collection

Motor Actuator

Data Transmission

Power

 


The CPU is PIC16F690 from MICROCHIP with 4K program space, 256 byte RAM. It comes with 256 bytes EEPROM so the circuit part does not need EEPROM to save data, which can effectively reduce the size of PCB.

The data concentrator performs testing on three wheel readings by means of resistance method, i.e., 1 tonnage, 10 tonnage and 100 tonnage, and then automatically determines the value of 1000 tonnage based on their changes.  Every wheel pending testing has different resistance network, depending on its mechanical structure.  During testing, two metal probes are used to strike the wheel to check or test the resistance values; and after A/D conversion the corresponding numbers for different resistance values are then obtained from the resistance table.

To ensure accuracy, the metal probes must be in very close contact with the wheel to ensure minimum contact resistance affecting testing results.  However, close contact will affect the wheel’s normal running.  Therefore, a non-touch structure is used, i.e. using a motor to drive a cam structure to control the metal probe.  At the time of testing, the motor drives the cam and makes sure the probe touches the wheel.  When the testing is done, the motor drives the cam so that the probe is detached from the wheel.

The data transmission module uses the RS-485 data port which is usually in passive receiving mode and will not actively sends out command.   When getting the meter reading command, the CPU controls the motor driven module and data collection module to work and complete collection of data from the wheel and transmits the data out.

The direct-reading remote transmission electronic module does not carry power and remains in a non-operating mode.  When an external device performs data communication with the meter, it will provide a 5-12V power supply to the meter.  After power-on-reset, the electronic module will be in a low power receiving mode, but once command is received, it will go into high speed working mode to handle the operation.  As soon as the operation is completed, it will resume to low power receiving mode until external power supply is cut off.

Since data collection is done by direct reading, it is not necessary to equip the meter with LCD display.  All data will be collected, read and displayed by the external device.

In order to make on-site installation and usage of the meters easy, it is necessary to install a sensor switch and a LED. When the external device is in process-checking mode, and if the sensor is closed, the meter will start to respond to the command of the external device.  Upon receipt of the right response from the external device, the LED will be on.  If no response or wrong response is received, the LED will flash for 5 seconds.


III.                Functional Description 

The following are the functions of the power-free and blind-spot-free direct-reading meter: 

1.          Data Collection

It can perform automatic data collection from 3 wheels simultaneously, at 1 tonnage, 10 tonnage, and 100 tonnage.

2.          Data Verification and Identification

Able to automatically determine high digit reading (upto 3 digits) based on the data collected from the 3 wheels mentioned above.  This means the meter can provide a water consumption record of up to 6 integral digits at its maximum.

3.          Intelligent Judgment

It can determine the direction of water flow right before meter reading based on the changes in the data collected.  At the same time, it can determine if the electronic motor module is in normal working condition according to receiving time of the receiving signal.  It can also determine if the data collection module is in normal condition from the resistance value.

4.          Communication

Data communication by RS-485 based on requirement and in response to different commands from the external device.

5.          Parameter Setting

External device can set parameters in the meter and initialize it through the RS- 485 data port.

6.          ”Hand-Shaking” Function

After the external device has sent out the “hand-shaking” command, which activates the sensor, the meter can automatically transmit information such as meter device serial number to the external device to complete the corresponding hand-shaking job.

7.          Frozen Function

The external device can send out “frozen” command. After receiving the command, the meter will collect data of the current water consumption volume and save it in EEPROM.

IV.                Types of Communication Command 

RS-485 is being used for data communication between the external device and the meter.  There are several types of data frame:

1.      Meter-reading Command Frame

The external device sends data collection command to the meter. Upon receipt of the command, the meter collects data.  Both the current water consumption volume and the last consumption volume are transmitted back, together with the related work status data.

2.      Parameter Setting Command Frame

The external device sends parameter setting command to the meter to set the meter number and the highest digit byte for water usage, and initialize the corresponding working status byte.  After setting, it will send back the right or wrong response signal to the external device.

3.      Password Change Command Frame

The external device sends password change command to the meter by using encryption method to set security protection key and partition number for data communication, and then sends back the right or wrong response signal to the external device.

4.      Frozen Command Frame

The external device sends Frozen Command to the meter for the meter to  perform data collection and save the data in EEPROM.  There will be no acknowledgement response.

5.      Hand-Shaking” Acknowledgement Command

The external device sends ” Hand-Shaking” commands to the meter.  Only under the situation when the switch is closed, will the meter  send the partition number and the meter serial number to the external device to complete the “hand-shaking” task.


V.                  Installation

The installation of the Power-Free and Blind-Spot-Free Direct-Reading Water Meter is the same as any mechanical meters.  The only difference is the need to install RS-485 data transmission passage.  The cable needed will depend on the location of the meters and the data concentrator.  After laying the cable and installing the meter and the data concentrator, one must record the device no. of the meter and the data concentrator and input into the business terminal so as to complete the corresponding relationship of the data information at the time of account opening by the user. 

Once connection is completed on-site, communication parameter testing must be carried out.  This is done by turning the on/off switch of the data concentrator to testing position and a testing card will be pasted on every meter.  Connection is correct if the indicator light on the meter is on, otherwise inspection must be carried out until getting the right signal.

Each and every meter must be tested this way before use.