A Fast MBUS Slave Search Method Based on Bit-by-Bit Filtering

Abstract

This invention relates to the field of water meters, and aims to provide a fast MBUS slave search method based on bit-by-bit filtering. This method should feature fast filtering speed and low modification cost. The technical solution is a fast MBUS slave search method based on bit-by-bit filtering, comprising the following steps: At the start of filtering, the data acquisition unit determines whether any water meters have a reporting requirement. If a reporting requirement exists, the data acquisition unit queries the address bit by bit. The water meter responds with a single bit based on the data acquisition unit's query. The data acquisition unit then forms an AND gate based on the single bit responses from multiple water meters and updates the address bit by bit to obtain the water meter address. The data acquisition unit communicates with the water meter based on the water meter address. Finally, the water meter no longer responds in this round of filtering.

Description

Technical Field

[0001] This invention relates to the field of water meters, specifically to a fast MBUS slave search method based on bit-by-bit filtering. Background Technology

[0002] MBUS (Meter-Bus) is a bus used for water meters and energy metering devices. Figure 3 It has the following characteristics: it has a power supply function, master-slave communication, one master and multiple slaves, and uses serial port frames to transmit data. Slave devices cannot directly exchange information with each other.

[0003] The water meter reading process uses a question-and-answer method: the data acquisition unit initiates a query, specifying the unique address of the water meter in the query message, and the selected water meter responds. If the water meter actively initiates communication, serial frames from multiple water meters may become mixed and unrecognizable. Therefore, the question-and-answer process can only be initiated by the data acquisition unit as the sole host.

[0004] When only a small number of water meters require reporting, such as low battery alarms or magnetic interference, the host cannot determine which meters have reporting needs and has to scan all water meters connected to the MBUS bus. Since each query takes 3 seconds, if there are 512 water meters, completing all the queries would take 25.6 minutes.

[0005] Similar to MBUS, the CAN bus is also a two-wire bus. On a CAN bus, slave devices can actively initiate communication without worrying about data being mixed and unrecognizable. This is because a CAN bus slave receives the bits being transmitted by other slave devices while transmitting each bit, allowing it to promptly yield to higher-priority messages. The physical structure of MBUS dictates that slave devices cannot directly exchange information. The arbitration method used by the CAN bus is not applicable to MBUS.

[0006] In the field of water meter reading, the current reporting frequency is usually on a daily basis. However, in an era of faster work and life pace, frequent population movement, and an expanding short-term rental market, water companies will consider the real-time response as a key factor when selecting data acquisition devices. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings in the above-mentioned background technology and provide a fast search method for MBUS slave devices based on bit-by-bit filtering. This method should have the characteristics of fast filtering speed and low modification cost.

[0008] The technical solution of this invention is:

[0009] The MBUS slave fast search method based on bit-by-bit filtering includes the following steps: At the start of filtering, the data acquisition unit determines whether there is a water meter with a reporting requirement. If there is a reporting requirement, the data acquisition unit queries the address bit by bit. The water meter sends a single-bit response based on the query of the data acquisition unit. The data acquisition unit then forms an AND gate based on the single-bit responses of multiple water meters and updates the address bit by bit to obtain the water meter address. The data acquisition unit communicates with the water meter based on the water meter address. Finally, the water meter no longer responds in this round of filtering.

[0010] The method includes the following steps:

[0011] S1. A new round of screening begins. The data acquisition unit broadcasts the screening command, and all water meters receive the screening command and prepare to respond to the screening.

[0012] S2. The data acquisition unit broadcasts a query to inquire about the existence of a command. Water meters with reporting needs respond. If the data acquisition unit detects a reporting need, it proceeds to step S3. Otherwise, it stops this round of screening.

[0013] S3. The new round of screening begins. The data acquisition unit sends query commands bit by bit according to the address cache. Water meters with reporting needs respond bit by bit. The data acquisition unit updates the address cache bit by bit. The final address cache obtained is the address of one of the water meters with reporting needs.

[0014] S4. The data acquisition unit communicates with the water meter using the water meter address alone. The data acquisition unit then sends a blocking command to the water meter. This screening process ends. Return to step S2.

[0015] The water meter address is a fixed address; the address cache has the same number of bits as the water meter address.

[0016] Before this round of screening begins, the data acquisition unit downloads the data table files, configures soft addresses according to the number of connected water meters, and writes them to each water meter. The soft addresses replace the fixed addresses, and the water meter addresses are soft addresses.

[0017] In step S2, the data acquisition unit broadcasts a query for the existence of a command. Water meters with reporting needs and water meters without reporting needs respond simultaneously. The data acquisition unit determines the reporting needs through an AND gate. If there are water meters with reporting needs, proceed to step S3; otherwise, stop this round of screening.

[0018] Step S3 includes:

[0019] S3.1. A new round of filtering begins. The data acquisition unit sends query commands bit by bit, starting from the first bit of the address cache.

[0020] S3.2 The data acquisition unit sends a query command, which includes the queried bit n and the address cache softAddrBuf; n = 0 for the first query;

[0021] S3.3. Water meters that need to report will compare the query command with the water meter address to obtain a temporary address string and a temporary cache string. If the two are equal, the water meter that needs to report will send the (n+1)th character of the water meter address.

[0022] When n=0, water meters that have a reporting requirement send the first character of the water meter address;

[0023] S3.4 The data acquisition machine updates the (n+1)th character in the address cache using an AND gate;

[0024] S3.5 If the queried bit is the last bit of the address cache, the current filtering ends; otherwise, the queried bit n = n + 1, and return to step S3.2;

[0025] The number of bits in the water meter address and the address cache increases gradually from left to right, or the number of bits in the water meter address and the address cache increases gradually from right to left.

[0026] The temporary address string is the first to the nth bits of the water meter address; the temporary cache string is the first to the nth bits of the address cache.

[0027] The soft addresses increase sequentially from smallest to largest.

[0028] The beneficial effects of this invention are:

[0029] This invention is a slave-based fast search method based on the MBUS bus. It can filter out the water meters that need to be reported without scanning all water meters one by one. Compared with periodic full-round scanning, this invention can achieve a rapid screening capability in minutes. Especially when dealing with a small number of water meters to be reported, the speed and efficiency advantages are more obvious. Moreover, this invention does not require changes to the physical layer, is compatible with old equipment and old full-round scanning methods, and has low transformation and upgrade costs. Attached Figure Description

[0030] Figure 1 This is a comparison diagram between the present invention and the traditional meter reading method.

[0031] Figure 2 This is a schematic diagram of an AND gate for current and an AND gate for time.

[0032] Figure 3 This is a schematic diagram of the MBUS bus. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0034] The MBUS slave fast search method based on bit-by-bit filtering includes the following steps:

[0035] S1. A new round of screening begins. The data acquisition unit broadcasts the screening command, and all water meters receive the screening command and prepare to respond to the screening.

[0036] Water meters have a built-in fixed address as the primary credential for identifying them, which is written on the meter dial. When the fixed address is too long, it is not conducive to speeding up the search. A soft address can be used as the secondary credential for identifying the water meter.

[0037] When setting the soft address: The data acquisition unit first downloads the table file, then configures the soft address according to the number of connected water meters and writes it to the water meter. The soft address of the water meter is binary and increments sequentially from small to large (it can start from 0). The soft address is only configured when downloading the table file and does not need to be configured again in subsequent filtering. The purpose of setting the soft address is to shorten the number of bits for address recognition, reduce the number of subsequent question and answer operations, and speed up the search.

[0038] In this method, a fixed address or a soft address can be used as the water meter address, depending on the actual situation.

[0039] The address cache has the same number of bits as the water meter address;

[0040] S2. The data acquisition unit broadcasts a query to inquire about the existence of a reporting command. Water meters with reporting needs respond. If the data acquisition unit detects a reporting need, it proceeds to step S3; otherwise, it stops this round of screening. The specific process is as follows:

[0041] The data acquisition unit broadcasts a query to inquire about the existence of a command. Water meters that report a demand respond by sending logic 0 (absorbing current). Water meters that do not report a demand respond by sending logic 1. The data acquisition unit uses an AND gate to determine the reporting demand. If there is a water meter that reports a demand, the data acquisition unit detects logic 0 and proceeds to step S3. If there is no water meter that reports a demand, the data acquisition unit detects logic 1 and stops the current round of screening.

[0042] S3. A new round of filtering begins. The data acquisition unit sends query commands bit by bit according to the address cache. Water meters with reporting requests respond bit by bit (of their water meter addresses). The data acquisition unit updates the address cache bit by bit, and the final address cache contains the addresses of one of the water meters with reporting requests. The specific process is as follows:

[0043] S3.1. A new round of filtering begins. The data acquisition unit sends query commands bit by bit, starting from the first bit of the address cache.

[0044] The number of bits in the water meter address and the address cache gradually increases from left to right. At this point, the first bit of the water meter address and the address cache is the leftmost bit, and the last bit is the rightmost bit. The query and update are performed from left to right, and the final water meter address is the minimum value among all addresses.

[0045] Alternatively, the number of bits in the water meter address and the address cache can be increased gradually from right to left. In this case, the first bit of the water meter address and the address cache is the rightmost bit, and the last bit is the leftmost bit. Queries and updates are performed from right to left.

[0046] S3.2 The data acquisition unit sends a query command, which includes the queried bit n and the address cache softAddrBuf; n = 0 for the first query;

[0047] S3.3. Water meters that need to report will compare the query command with the water meter address to obtain a temporary address string and a temporary cache string. If the two are equal, the water meter that needs to report will send the (n+1)th character of the soft address.

[0048] The temporary address string is the first to the nth bits of the water meter address; the temporary cache string is the first to the nth bits of the address cache.

[0049] When n=0, water meters that have a reporting requirement send the first character of the water meter address;

[0050] S3.4 The data acquisition machine updates the (n+1)th character of the address cache softAddrBuf using an AND gate;

[0051] S3.5 If the queried bit is the last bit of the water meter address, all bits in the address cache are updated, the current filtering ends, and the obtained address cache is one of the water meter addresses that has a reporting requirement; otherwise, the queried bit n = n + 1, return to step S3.2;

[0052] S4. The data acquisition unit communicates with the water meter using the water meter address (address cache) alone. The data acquisition unit then sends a blocking command to the water meter. This filtering process ends, and the process returns to step S2.

[0053] The MBUS bus specifies that the master (data acquisition unit) represents logic 1 with 36V and logic 0 with 24V, while the slave (water meter) represents logic 1 with 1.5mA of current and logic 0 with an additional 11-20mA. Typically, the slave only detects voltage, so slaves cannot directly exchange information. Although it's possible to achieve slave-to-slave communication through more sensitive detection, this invention focuses on standard equipment and does not consider modifying the physical layer.

[0054] The basic idea of ​​this invention is to implement AND gates at both the current and time levels using a single bit. Figure 2).

[0055] 1. AND gate at the current level:

[0056] If one water meter sends a logic 0 (increased current) and another water meter sends a logic 0 (increased current), the data acquisition unit will detect an increase in current (logic 0).

[0057] If one water meter sends logic 0 (current increases) and the other water meter sends logic 1 (current remains unchanged), the data acquisition unit will detect that the current increases (logic 0).

[0058] If one water meter sends logic 1 (current remains unchanged) and the other water meter sends logic 0 (current increases), the data acquisition unit will detect an increase in current (logic 0).

[0059] If one water meter sends logic 1 (current remains unchanged) and another water meter sends logic 1 (current remains unchanged), the result detected by the data acquisition machine will be that the current remains unchanged (logic 1).

[0060] 2. Since water meters react at different speeds, the start time of sending a single bit may be asynchronous. In this case, a time-level AND gate is used:

[0061] If one water meter sends a logic 0 (increased current) and another water meter sends a logic 0 (increased current), and the two are different, then the result detected by the data acquisition machine during this time interval is increased current (logic 0).

[0062] If one water meter sends logic 0 (current increases) and another water meter sends logic 1 (current remains unchanged), and the two are different, then the result detected by the data acquisition machine during this time interval is that the current increases (logic 0).

[0063] If one water meter sends logic 1 (current remains unchanged) and another water meter sends logic 0 (current increases), and the two are different, then the result detected by the data acquisition machine during this time interval is that the current increases (logic 0).

[0064] If one water meter sends logic 1 (current unchanged) and another water meter sends logic 1 (current unchanged), and the two are different, then the result detected by the data acquisition machine during this time interval is that the current remains unchanged (logic 1).

[0065] Example 1

[0066] The data acquisition unit connects to a total of 512 water meters (512 is the number of water meters in the standard configuration). Since the fixed address is long, a soft address is used as the water meter address. The soft address is configured as 0-511 (binary is 000000000-111111111, a total of 9 bits).

[0067] There are three water meters (meter A, meter B, and meter C) that have a reporting requirement. The soft address of meter A is 484 (111100100), the soft address of meter B is 490 (111101010), and the soft address of meter C is 500 (111110100).

[0068] The first bit of the water meter address and the address cache is the leftmost bit, and the last bit is the rightmost bit. Queries and updates are performed from left to right.

[0069] A new round of screening begins. The data acquisition unit broadcasts a screening command (Question 1). All water meters receive the screening command and prepare to respond to the screening.

[0070] The data acquisition unit broadcasts a query to inquire about the existence of commands (2 questions). Tables A, B, and C have reporting requirements, so it sends logic 0 (2 answers). The data acquisition unit detects logic 0 and starts this round of filtering. If the data acquisition unit detects logic 1, it means there is no reporting requirement, and this round of filtering ends.

[0071] digit-by-digit lookup begins:

[0072] ①The data acquisition unit sends a query command (question 3), the queried bit n=0, the address cache softAddrBuf=000000000;

[0073] Since n=0, all three meters simultaneously send (3 answers) logic 1 (the first bit of the water meter address);

[0074] The data acquisition unit obtains a logic 1 through an AND gate, updates the first bit of the address cache to 1, and sets the address cache softAddrBuf = 100000000;

[0075] ②The data acquisition unit sends a query command (question 4), the queried bit n=1, the address cache softAddrBuf=100000000;

[0076] The temporary cache string is 1, and the temporary address strings of tables A, B, and C are all 1. The temporary cache string is the same as the temporary address strings of the three tables.

[0077] The second bit (the second bit from left to right) of the water meter address in tables A, B, and C are all 1, so all three tables send logic 1 (4 answers) simultaneously.

[0078] The data acquisition unit obtains a logic 1 through an AND gate, updates the second bit of the address cache to 1, and the address cache softAddrBuf = 110000000;

[0079] ③ The data acquisition unit sends a query command (5 questions), the queried bits n=2, and the address cache softAddrBuf=1100000000

[0080] The temporary cache string is 11. The temporary address strings of tables A, B, and C are all 11. The temporary cache string is the same as the temporary address strings of the three tables.

[0081] The third bit (the third bit from left to right) of the water meter address in tables A, B, and C is all 1, so all three meters send logic 1 (5 answers) simultaneously;

[0082] The acquisition unit obtains a logic 1 through an AND gate, updates the 3rd bit of the address cache to 1, and the address cache softAddrBuf = 111000000;

[0083] ④ The data acquisition unit sends a query command (6 questions), the queried bits n=3, the address cache softAddrBuf=111000000;

[0084] The temporary cache string is 111. The temporary address strings of tables A, B, and C are all 111. The temporary cache string is the same as the temporary address strings of the three tables.

[0085] The fourth bit (the fourth bit from left to right) of the water meter address in tables A, B, and C is all 1, so all three tables send logic 1 (6 answers) simultaneously.

[0086] The data acquisition unit obtains a logic 1 through an AND gate, updates the 4th bit of the address cache to 1, and the address cache softAddrBuf = 111100000;

[0087] ⑤ The data acquisition unit sends a query command (question 7), the queried bits n=4, the address cache softAddrBuf=111100000;

[0088] The temporary cache string is 1111. The temporary address strings of tables A, B, and C are all 1111. The temporary cache string is the same as the temporary address strings of the three tables.

[0089] The 5th bit (the 5th bit from left to right) of the water meter address in both A and B is 0, therefore A and B send logic 0 (7 answers);

[0090] The 5th bit (the 5th bit from left to right) of the water meter address in table C is 1, therefore table C sends logic 1 (7 answers);

[0091] The data acquisition unit obtains logic 0 through an AND gate, updates the 5th bit of the address cache to 0, and the address cache softAddrBuf = 111100000;

[0092] ⑥ The data acquisition unit sends a query command (question 8), the queried bits n=5, the address cache softAddrBuf=111100000;

[0093] The temporary cache string is 11110. The temporary address strings of tables A and B are both 11110. The temporary cache string is the same as the temporary address strings of tables A and B. The temporary address string of table C is 11111.

[0094] The 6th bit of the water meter address of meter A (the 6th bit from left to right) is 0, therefore meter A sends logic 0 (8 answers);

[0095] The 6th bit of the water meter address of table B (the 6th bit from left to right) is 1, therefore table B sends logic 1 (8 answers);

[0096] The acquisition unit obtains logic 0 through an AND gate, updates the 6th bit of the address cache to 0, and the address cache softAddrBuf = 111100000;

[0097] ⑦ The data acquisition unit sends a query command (question 9), the queried bits n=6, the address cache softAddrBuf=111100000;

[0098] The temporary cache string is 111100, and the temporary address strings of table A are all 111100. The temporary cache string is the same as the temporary address string of table A; the temporary address strings of table B are all 111101.

[0099] The 7th bit of the water meter address of meter A (the 7th bit from left to right) is 1, so meter A sends logic 1 (9 answers);

[0100] The acquisition unit obtains a logic 1 through an AND gate, updates the 7th bit of the address cache to 1, and the address cache softAddrBuf = 111100100;

[0101] ⑧ The data acquisition unit sends a query command (10 questions), the queried bit n=7, the address cache softAddrBuf=111100100;

[0102] The temporary cache string is 1111001, and the temporary address strings of table A are all 1111001. The temporary cache string is the same as the temporary address string of table A.

[0103] The 8th bit of the water meter address of meter A (the 8th bit from left to right) is 0, therefore meter A sends logic 0 (10 answers);

[0104] The acquisition unit obtains logic 0 through an AND gate, updates the 8th bit of the address cache to 0, and the address cache softAddrBuf = 111100100;

[0105] ⑨ The data acquisition unit sends a query command (question 11), the queried bits n=8, the address cache softAddrBuf=111100100;

[0106] The temporary cache string is 11110010, and the temporary address string of table A is also 11110010. The temporary cache string is the same as the temporary address string of table A.

[0107] The 9th bit of the water meter address of meter A (the 9th bit from left to right) is 0, therefore meter A sends logic 0 (11 answers);

[0108] The data acquisition unit obtains logic 0 through an AND gate, updates the 9th bit of the address cache to 0, and the address cache softAddrBuf = 111100100;

[0109] ⑩ The queried digit is the last digit of the water meter address; this filtering process is now complete.

[0110] The address cache is softAddrBuf = 111100100, and the smallest water meter address is obtained from the three tables;

[0111] The data acquisition unit uses the address cache (111100100) to communicate with A separately (Question 12). Table A reports data (Answer 12). The data acquisition unit then sends a masking command to table A (Question 13). Table A will not send logic 0 again in this round of filtering. Tables B and C continue to filter according to the above steps: the second filtering results in the water meter address of table B, and the third filtering results in the water meter address of table C.

[0112] As shown above, only 13 questions and answers are needed to select a water meter to report; in contrast, the traditional full-scan method requires 512 questions and answers. Each question and answer takes 3 seconds. Figure 1 As shown, for this invention, each water meter only requires 13 × 3 = 39 seconds, while the traditional method requires 512 × 3 / 60 = 25.6 minutes. When the number of meters to be reported simultaneously is less than 512 / 13 = 39, this invention has a significant speed advantage. When there are more than 39 water meters, the speed is actually slower than the traditional method. However, since this invention does not require changes to the physical layer, it can switch between the search method provided by this invention and the traditional full-round scanning method. The switching strategy is based on the judgment of a large number of reporting needs and needs to be analyzed according to the specific situation. This invention does not provide a switching strategy.

[0113] Example 2

[0114] The difference from Example 1 is that the first bit of the water meter address and the address cache is the rightmost bit, and the last bit is the leftmost bit. Queries and updates are performed from right to left. The first filter yields the water meter addresses for table A, the second filter yields the water meter addresses for table C, and the third filter yields the water meter addresses for table B. Each filter requires only 13 queries.

[0115] This invention uses an MBUS data acquisition unit to filter MBUS water meters to be reported. The filtering method is that the data acquisition unit queries the water meter address bit by bit, and the water meter sends a single bit response to the query. The single bit responses of multiple water meters form an AND gate, and the water meters that have been found will not respond again in this round of filtering.

[0116] The features of this invention are as follows: the data acquisition unit uses broadcast-based access to the water meter, which is different from the traditional point-to-point access method; the data acquisition unit uses a shorter soft address to access the water meter, which is different from the traditional method of using a longer address; the data acquisition unit uses a bit-by-bit query method to filter the address, which is different from the traditional method of giving the address completely in one frame; and the water meter uses a single-bit response, which is different from the traditional method of using serial port frames for response.

[0117] The advantages of this invention are:

[0118] The characteristics of the MBUS bus are used to implement AND gates at the current and time levels. Compared with the CAN bus, there is no need for slave-to-slave listening, avoiding slave-to-slave conflicts, making it very suitable for the MBUS bus. By configuring the soft address, a new round of filtering begins, and the filtering is carried out in sequence through the complete process of querying existence, bit-by-bit query, and current round masking. The overall process is short, reliable, and fast.

[0119] The accompanying drawings illustrate preferred embodiments of the invention. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

Claims

1. A bit-by-bit screening-based MBUS slave fast search method, comprising the following steps: S1. A new round of screening starts, and a screening command is broadcast by a collector, and all water meters receive the screening command and prepare to respond to the screening; S2. The collector broadcasts an inquiry existing command, and the water meters with reporting requirements respond, and send logic 0, and the water meters without reporting requirements respond, and send logic 1, and the collector judges the reporting requirements through an AND gate, if there are water meters with reporting requirements, the collector detects logic 0, and enters step S3, if there are no water meters with reporting requirements, the collector detects logic 1, and stops the current round of screening; S3 comprises the following steps: S3.

1. A new screening starts, and the collector starts from the first bit of an address cache, and sends a query command bit by bit; S3.

2. The collector sends a query command, and the query command comprises a queried bit n and an address cache softAddrBuf; the first time n = 0; S3.

3. The water meters with reporting requirements compare the query command with the water meter address, obtain a temporary address string and a temporary cache string, and if the two are equal, the water meters with reporting requirements send the (n+1)th character of the water meter address; When n = 0, the water meters with reporting requirements send the 1st character of the water meter address; S3.

4. The collector updates the (n+1)th character of the address cache through an AND gate; S3.

5. If the queried bit is the last bit of the address cache, the current screening ends; otherwise, the queried bit n = n+1, and the step S3.2 is returned; S4. The collector communicates with the water meter using the water meter address, and the collector sends a shielding command to the water meter, and the current screening ends, and the step S2 is returned; The water meter address is a fixed address; the address cache and the water meter address have the same number of bits; The temporary address string is part of the 1st to n th bit of the water meter address; and the temporary cache string is part of the 1st to n th bit of the address cache; The AND gate is an AND gate at a current level and an AND gate at a time level considering the time response difference of the water meter.

2. The method for fast search of MBUS slave based on bit-by-bit filtering according to claim 1, characterized in that: Before the current screening starts, the collector downloads a meter file, configures a soft address according to the number of connected water meters, and writes the soft address into each water meter, and the water meter address is replaced by the soft address.

3. The method for fast search of MBUS slave based on bit-by-bit filtering according to claim 2, characterized in that: The step S3 comprises that the number of bits of the water meter address and the address cache gradually increases along the order from left to right, or the number of bits of the water meter address and the address cache gradually increases along the order from right to left.

4. The method for fast search of MBUS slave based on bit-by-bit filtering according to claim 3, characterized in that: The soft address increases from small to large.

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