Electronic differential pressure liquid level meter and software synchronization method

Abstract

The application provides an electronic differential pressure liquid level meter and a software synchronization method.The electronic differential pressure liquid level meter comprises a main pressure transmitter and an auxiliary pressure transmitter, the main pressure transmitter and the auxiliary pressure transmitter are electrically connected through a communication cable, the main pressure transmitter and the auxiliary pressure transmitter are respectively communicated with a measured pipeline, and a measured liquid level in the pipeline is formed in the measured pipeline.The main pressure transmitter obtains the pressure value of the auxiliary pressure transmitter through the communication cable, calculates the pressure difference, and obtains the liquid level height according to the liquid pressure formula.The technical scheme can accurately measure the liquid level with a rapid change rate, does not need to increase additional hardware cost, improves the measurement precision, and widens the application field and range of the electronic differential pressure transmitter.

Description

Technical Field

[0001] This invention relates to the field of electronic differential pressure level gauge technology, specifically to an electronic differential pressure level gauge and a software synchronization method. Background Technology

[0002] There are numerous applications of liquid level measurement in actual industrial settings. While in most scenarios the change in the measured liquid level is very slow, and conventional electronic differential pressure level gauges can provide relatively accurate readings, there are also a small number of cases where the measured liquid level changes very rapidly. For these special cases, conventional electronic differential pressure level gauges cannot meet the accuracy requirements. The reasons for this can be seen from... Figure 2 and Figure 3 The comparison shows that, ideally, the differential pressure values ​​of A1 and A2 should be as follows: Figure 2 As shown, there is no error. However, the actual situation is... Figure 3 As shown, A1 can only obtain the pressure value uploaded by A2 after each communication frame. This pressure value of A2 is not actually updated until the next communication frame arrives, as indicated by the dotted line in the figure, while the actual pressure value of A2 continues to rise. Therefore, the differential pressure value measured by A1 is inaccurate, and consequently, the calculated liquid level is also inaccurate. Theoretically, this problem can be solved by increasing the communication frequency, i.e., reducing the time interval between frames, but this is practically infeasible. The reason is:

[0003] (1) The control chips used in pressure transmitters are often low in cost and high in reliability but poor in performance, which makes it impossible to achieve a fast communication interval. Reaching a communication interval of 100 milliseconds is already the limit.

[0004] (2) In order to ensure communication reliability and communication distance, industrial sites often use a lower baud rate and protocols with lower communication performance such as HART or RS485, which objectively cannot shorten the communication interval too much.

[0005] (3) In industrial settings, due to cabling costs, multiple devices may be connected to a single communication bus. Other devices may crowd out the communication cables and compete for communication time, making it impossible to achieve very real-time communication.

[0006] In summary, ordinary electronic differential pressure level gauges cannot accurately measure rapidly changing liquid levels in industrial settings, and there is a problem of asynchronous measurement times between the two pressure gauges. Current technology uses a hardware synchronization scheme to solve this problem, which involves adding a hardware synchronization line independent of the communication cable. A1 continuously triggers A2 to synchronize via this line, recording one pressure sampling point each time. Finally, communication acquires all pressure sampling points, resulting in an accurate liquid level curve. However, this method has the following drawbacks:

[0007] (1) It requires the addition of hardware synchronization cables, which significantly increases costs.

[0008] (2) The level gauge is a low-power product. Adding cable connections will increase the power consumption of the device and affect the low current alarm function. Summary of the Invention

[0009] To address the shortcomings of existing technologies, the purpose of this invention is to provide an electronic differential pressure level gauge and a software synchronization method that can accurately measure rapidly changing liquid levels without incurring additional hardware costs.

[0010] The present invention provides an electronic differential pressure level gauge, comprising a main pressure transmitter and an auxiliary pressure transmitter, wherein the main pressure transmitter and the auxiliary pressure transmitter are electrically connected via a communication cable, and the main pressure transmitter and the auxiliary pressure transmitter are respectively connected to the pipeline under test, wherein the pipeline level under test is formed.

[0011] Furthermore, the main pressure transmitter and the auxiliary pressure transmitter are respectively connected to a connecting pipe, the connecting pipe is connected to a connector, and the connector is connected to the measured pipeline.

[0012] Furthermore, the liquid level being measured in the pipeline is located between the two joints.

[0013] Furthermore, it also includes a fixed bracket, which is detachably connected to the main pressure transmitter and the auxiliary pressure transmitter respectively.

[0014] Furthermore, the connecting pipe is an oil-filled capillary tube, and the joint is a flange diaphragm joint.

[0015] This invention also provides a software synchronization method for an electronic differential pressure level gauge, comprising:

[0016] The main pressure transmitter sends a first synchronization frame, and the pressure value storage area of ​​the main pressure transmitter points from the first main storage area to the second main storage area.

[0017] The auxiliary pressure transmitter receives the first synchronization frame, and the pressure value storage area of ​​the auxiliary pressure transmitter points from the first auxiliary storage area to the second auxiliary storage area.

[0018] The auxiliary pressure transmitter sends the pressure value stored in the first auxiliary storage area to the main pressure transmitter;

[0019] The main pressure transmitter receives the pressure value stored in the first auxiliary storage area;

[0020] The main pressure transmitter processes the pressure values ​​stored in the first main storage area and the pressure values ​​stored in the first auxiliary storage area to obtain the first differential pressure value.

[0021] The first differential pressure value is converted into liquid level to obtain the measured liquid level in the first pipeline.

[0022] Furthermore, the method also includes:

[0023] The main pressure transmitter sends a second synchronization frame, and the pressure value storage area of ​​the main pressure transmitter points from the second main storage area to the first main storage area;

[0024] The auxiliary pressure transmitter receives the second synchronization frame, and the pressure value storage area of ​​the auxiliary pressure transmitter points from the second auxiliary storage area to the first auxiliary storage area.

[0025] The auxiliary pressure transmitter sends the pressure value stored in the second auxiliary storage area to the main pressure transmitter;

[0026] The main pressure transmitter receives the pressure value stored in the second auxiliary storage area;

[0027] The main pressure transmitter processes the pressure values ​​stored in the second main storage area and the pressure values ​​stored in the second auxiliary storage area to obtain the second differential pressure value;

[0028] The second differential pressure value is converted into liquid level to obtain the measured liquid level in the second pipeline.

[0029] Furthermore, the synchronization count values ​​of the main pressure transmitter and the auxiliary pressure transmitter are periodically reset to zero. The main pressure transmitter is reset to zero when sending a synchronization frame, and the auxiliary pressure transmitter is reset to zero when receiving a synchronization frame.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The present invention provides an electronic differential pressure level gauge and its software synchronization method. The electronic differential pressure level gauge is a measuring device composed of a main pressure transmitter and an auxiliary pressure transmitter. In this device, the main pressure transmitter acquires the pressure value of the auxiliary pressure transmitter via a communication cable, calculates the pressure difference, and then obtains the liquid level height according to the liquid pressure formula. The electronic differential pressure level gauge triggers the main and auxiliary pressure transmitters to record a series of dense pressure value sampling points through a special synchronization frame. The pressure sampling values ​​of the main and auxiliary pressure transmitters correspond one-to-one at each moment. After the main pressure transmitter acquires all the pressure values ​​between two synchronization frames from the auxiliary pressure transmitter, it can obtain an accurate differential pressure level curve. This technical solution can accurately measure rapidly changing liquid levels without increasing additional hardware costs, improving measurement accuracy and broadening the application fields and scope of electronic differential pressure transmitters. Attached Figure Description

[0032] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0033] Figure 1 This is a schematic diagram of the structure of an electronic differential pressure level gauge provided in an embodiment of the present invention;

[0034] Figure 2 A schematic diagram of the differential pressure values ​​of A1 and A2 under ideal conditions provided for an embodiment of the present invention;

[0035] Figure 3 This is a schematic diagram of the differential pressure values ​​of A1 and A2 under actual conditions in the prior art provided by the embodiments of the present invention;

[0036] Figure 4 A schematic diagram of the differential pressure values ​​of A1 and A2 under software synchronization conditions provided in an embodiment of the present invention;

[0037] Figure 5 This is a schematic diagram illustrating the definition of a common communication frame provided in an embodiment of the present invention;

[0038] Figure 6 This is a schematic diagram illustrating the definition of a synchronization communication frame provided in an embodiment of the present invention;

[0039] Figure 7 This is a spatial diagram of a dual storage space provided in an embodiment of the present invention;

[0040] Figure 8 A schematic diagram of a timer synchronization method provided in an embodiment of the present invention;

[0041] Figure 9 This is a flowchart illustrating a software synchronization method for an electronic differential pressure level gauge provided in an embodiment of the present invention.

[0042] In the picture:

[0043] 1. Main pressure transmitter; 2. Auxiliary pressure transmitter; 3. Mounting bracket; 4. Communication cable; 5. Connecting pipe; 6. Connector; 7. Measured liquid level in the pipeline. Detailed Implementation

[0044] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0045] Please see Figure 1The diagram shows a structural schematic of an electronic differential pressure level gauge provided in an embodiment of the present invention. The electronic differential pressure level gauge includes a main pressure transmitter 1, an auxiliary pressure transmitter 2, and a fixed bracket 3. The fixed bracket 3 is detachably connected to the main pressure transmitter 1 and the auxiliary pressure transmitter 2. The main pressure transmitter 1 and the auxiliary pressure transmitter 2 are electrically connected through a communication cable 4. The main pressure transmitter 1 and the auxiliary pressure transmitter 2 are respectively connected to a connecting pipe 5. The connecting pipe 5 is connected to a connector 6. The connector 6 is connected to the pipe being measured. A measured liquid level 7 is formed in the pipe being measured. The measured liquid level 7 is located between the two connectors 6.

[0046] Among them, the connecting pipe 5 is an oil-filled capillary tube, and the connector 6 is a flange diaphragm connector.

[0047] Please see Figure 4 The diagram illustrates the differential pressure values ​​of A1 and A2 under software synchronization, as provided in an embodiment of the present invention. This electronic differential pressure level gauge features software synchronization. Through a special synchronization frame, A1 and A2 are triggered to record a series of dense pressure value sampling points, and the pressure sampling values ​​of A1 and A2 at each moment correspond one-to-one. After A1 obtains all the pressure values ​​between two synchronization frames of A2, it can obtain an accurate differential pressure level curve. A1 is the main pressure transmitter 1, and A2 is the auxiliary pressure transmitter 2.

[0048] This invention also provides a software synchronization method for an electronic differential pressure level gauge, comprising:

[0049] The main pressure transmitter sends a first synchronization frame, and the pressure value storage area of ​​the main pressure transmitter points from the first main storage area to the second main storage area.

[0050] The auxiliary pressure transmitter receives the first synchronization frame, and the pressure value storage area of ​​the auxiliary pressure transmitter points from the first auxiliary storage area to the second auxiliary storage area.

[0051] The auxiliary pressure transmitter sends the pressure value stored in the first auxiliary storage area to the main pressure transmitter;

[0052] The main pressure transmitter receives the pressure value stored in the first auxiliary storage area;

[0053] The main pressure transmitter processes the pressure values ​​stored in the first main storage area and the pressure values ​​stored in the first auxiliary storage area to obtain the first differential pressure value.

[0054] The first differential pressure value is converted into liquid level to obtain the measured liquid level in the first pipeline.

[0055] The main pressure transmitter sends a second synchronization frame, and the pressure value storage area of ​​the main pressure transmitter points from the second main storage area to the first main storage area;

[0056] The auxiliary pressure transmitter receives the second synchronization frame, and the pressure value storage area of ​​the auxiliary pressure transmitter points from the second auxiliary storage area to the first auxiliary storage area.

[0057] The auxiliary pressure transmitter sends the pressure value stored in the second auxiliary storage area to the main pressure transmitter;

[0058] The main pressure transmitter receives the pressure value stored in the second auxiliary storage area;

[0059] The main pressure transmitter processes the pressure values ​​stored in the second main storage area and the pressure values ​​stored in the second auxiliary storage area to obtain the second differential pressure value;

[0060] The second differential pressure value is converted into liquid level to obtain the measured liquid level in the second pipeline.

[0061] The synchronization count values ​​of the main pressure transmitter and the auxiliary pressure transmitter are periodically reset to zero. The main pressure transmitter is reset to zero when sending a synchronization frame, and the auxiliary pressure transmitter is reset to zero when receiving a synchronization frame.

[0062] In a specific embodiment, this electronic differential pressure level gauge software synchronization method requires the following stages: (1) defining synchronization frames; (2) allocating dual storage space; (3) establishing synchronization rules; (4) overall synchronization process; and (5) synchronization data processing. Specifically, as follows:

[0063] (1) Define synchronization frame

[0064] Please see Figure 5 and Figure 6 , Figure 5 This is a schematic diagram illustrating the definition of a typical communication frame according to an embodiment of the present invention. Figure 6 This is a schematic diagram illustrating the definition of a synchronization communication frame provided in an embodiment of the present invention; for example... Figure 5 and Figure 6 As shown, a conventional electronic differential pressure level gauge can only read one data value per communication. Compared to conventional communication frames, this invention defines a new frame structure, namely, a synchronous communication frame. The synchronous communication frame adds a 2-byte synchronization instruction code to the A1 sending frame to initiate synchronization; the A2 reply frame adds the number of data items and multiple pressure data values. Here, A1 is the main pressure transmitter, and A2 is the auxiliary pressure transmitter.

[0065] (2) Create dual storage space

[0066] Please see Figure 7 The diagram shown is a spatial schematic of a dual storage space provided in an embodiment of the present invention; as follows: Figure 7As shown, this invention defines a dual-storage-area memory storage structure. A1 allocates two 400-byte storage spaces (denoted as A1S100 and A1S200) within its internal SRAM storage space, each capable of storing 100 pressure values, used to store the pressure values ​​recorded between two synchronization communication frames. Similarly, A2 also allocates A2S100 and A2S200 areas to store its own pressure values. A1S100 is the first main storage area, A1S200 is the second main storage area, A2S100 is the first auxiliary storage area, and A2S200 is the second auxiliary storage area.

[0067] The dual-storage structure employs a space-for-time design philosophy, which has the advantage of shortening memory operation time and overcoming the problem of missing sampled values ​​during communication.

[0068] (3) Establish synchronization rules

[0069] Please see Figure 8 The diagram shown is a schematic representation of a timer synchronization method provided by an embodiment of the present invention; as follows: Figure 8 As shown, this invention employs a timer synchronization method. A timer resource is enabled in the control chip A1. This timer generates a 5-millisecond interrupt, recording one pressure value every 5 milliseconds and storing it sequentially in the A1S100 area. The pressure value sequence number serves as the synchronization counter value, denoted as "00, 01, 02...". A2 is constructed using a similar method.

[0070] In the diagram, time T1 represents the pressure value recording interval, which is 5 milliseconds. Of course, the time interval T1 can be adjusted according to the sampling rate of different pressure transmitters. T2 is the execution time for pressure value recording in the interrupt function. For a conventional 4MHz power frequency control chip, T2 is approximately 10 microseconds, which can be ignored.

[0071] Of course, due to the errors of their respective components, the T1 time of A1 and A2 cannot be exactly 5 milliseconds. It's possible that A1's T1 time is 4.97 milliseconds and A2's T1 time is 4.99 milliseconds. Over time, this will lead to accumulated errors. Therefore, the synchronization count values ​​of A1 and A2 must be periodically reset to zero to prevent excessive accumulated errors. Figure 8 As shown, A1 is cleared to zero when a synchronization frame is sent, and A2 is cleared to zero when a synchronization frame is received, thus avoiding the problem of accumulated errors.

[0072] (4) Overall synchronization process

[0073] Please see Figure 9 The diagram shows a flowchart of a software synchronization method for an electronic differential pressure level gauge provided in an embodiment of the present invention; the complete synchronization process is as follows: Figure 9As shown, the present invention uses a dual-storage area alternating storage method to record synchronization values.

[0074] Before sending the N+1th synchronization frame, the pressure value of A1 is stored in the A1S100 area, and the pressure value of A2 is stored in the A2S100 area.

[0075] Now, A1 sends the (N+1)th synchronization frame. After sending the two bytes of synchronization command code 77 and 88, the pressure value storage area points to area A1S200. Upon receiving the synchronization frame command code 77 and 88, A2's pressure value storage area points to area A2S200. Then, A2 begins packaging and uploading the pressure data from the Nth to the (N+1)th synchronization frame, sending the data in area A2S100 to A1. After sending, A2 clears the synchronization count value in area A2S100. A1 can process the data received from A2; see section 5) for details. After processing, A1 clears the synchronization count value in area A1S100. This completes the single synchronization process.

[0076] Then A1 sends the N+2th synchronization frame, and so on in a loop.

[0077] Among them, the N+1th synchronization frame is the first synchronization frame, and the N+2th synchronization frame is the second synchronization frame.

[0078] The advantage of using the above synchronization method is that it can avoid the following problems:

[0079] ① The control chips of pressure transmitters generally have poor performance and cannot operate in a multi-threaded manner, resulting in significant time consumption when processing large amounts of data. For example, a 4MHz power frequency control chip can take more than 1 millisecond to copy just 400 bytes of data. This invention employs dual-memory alternating storage to avoid large-scale data copying and migration operations, reducing time loss and increasing synchronization accuracy. Furthermore, the dual storage area also helps retain pressure data when communication occasionally fails.

[0080] ② Communication time consumption cannot be ignored. Taking the commonly used baud rate of 9600 as an example, transmitting just one byte will take about 1 millisecond. Therefore, this invention adopts a timer interrupt method to increase the priority of critical tasks, ensure the accuracy and reliability of synchronous pressure value recording, prevent pressure value recording from being interrupted by other secondary tasks such as communication, and reduce the omission of synchronous pressure values.

[0081] (5) Synchronous data processing

[0082] In the overall synchronization process, A1 and A2 continuously synchronize data. Each time A1 communicates, it can obtain the synchronization data group of A2 during the most recent communication interval and process the data.

[0083] As shown in Table 1, assuming that A1 received 9 sets of synchronization data this time, namely data "00-08" in zone A2S100, denoted as "A2_P01-A2_P09". A1's own data "00-08" is denoted as "A1_P01-A1_P09". Finally, the pressure values ​​of A1 and A2 for each synchronization are subtracted, i.e., "P1 = A1_P01 - A2_P01", to obtain 9 accurate differential pressure values ​​from P1 to P9, which can then be converted into liquid level using the liquid pressure formula.

[0084] The A1 interface only displays the liquid level converted from the latest differential pressure value P9. All other liquid level values ​​are stored as historical data in the A1's external memory, which is polled when full. When the host computer communicates with the A1, it can retrieve all the most recently measured historical liquid level values ​​and plot an accurate liquid level curve.

[0085] Of course, there may be cases where the number of A2 synchronized data received is not equal to the number of A1 data to be synchronized. In such cases, the calculation is based on the smaller number, and losing one or two values ​​will not have a significant impact on the overall accuracy.

[0086] In summary, conventional electronic differential pressure level gauges can only obtain one differential pressure value per communication cycle, and the differential pressure value is not very accurate due to timing asynchrony, as shown in Table 2. In contrast, the electronic differential pressure level gauge described in this invention can obtain multiple differential pressure values ​​with synchronized timing, ensuring a one-to-one correspondence between the differential pressure values ​​at each moment, thus significantly improving measurement accuracy.

[0087]

[0088] Table 1

[0089]

[0090] Table 2

[0091] In this embodiment, a complete synchronization scheme is constructed by using a synchronization frame structure, a dual-memory alternating storage structure, and a timer synchronization rule. This scheme can solve the signal synchronization problem that is difficult to solve by conventional electronic differential pressure level gauges with just software, without hardware modification costs, significantly improving measurement accuracy and broadening the application fields and scope of electronic differential pressure transmitters.

[0092] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. An electronic differential pressure level gauge, characterized in that, It includes a main pressure transmitter (1) and an auxiliary pressure transmitter (2). The main pressure transmitter (1) and the auxiliary pressure transmitter (2) are electrically connected through a communication cable (4). The main pressure transmitter (1) and the auxiliary pressure transmitter (2) are respectively connected to the pipeline under test, and the pipeline under test liquid level (7) is formed in the pipeline under test. The main pressure transmitter (1) and the auxiliary pressure transmitter (2) are configured as follows: The electronic differential pressure level gauge triggers the main pressure transmitter (1) and the auxiliary pressure transmitter (2) to record a series of dense pressure value sampling points through a synchronization frame. The pressure sampling values ​​of the main pressure transmitter (1) and the auxiliary pressure transmitter (2) at each moment correspond one-to-one. After the main pressure transmitter (1) obtains all the pressure values ​​between the two synchronization frames of the auxiliary pressure transmitter (2) through communication, it can obtain an accurate differential pressure level curve to accurately measure the level with a fast change rate. The main pressure transmitter (1) opens two storage spaces in the SRAM storage space inside its control chip, which are respectively called the first main storage area and the second main storage area, to store the pressure values ​​recorded during the two synchronization communication frames. The auxiliary pressure transmitter (2) also opens a first auxiliary storage area and a second auxiliary storage area to store its own pressure values. The electronic differential pressure level gauge records the synchronization values ​​by alternating storage in the dual storage areas. The synchronization count values ​​of the main pressure transmitter and the auxiliary pressure transmitter are periodically cleared to zero. The main pressure transmitter clears to zero when sending the synchronization frame, and the auxiliary pressure transmitter clears to zero when receiving the synchronization frame to prevent excessive cumulative error.

2. The electronic differential pressure level gauge according to claim 1, characterized in that, The main pressure transmitter (1) and the auxiliary pressure transmitter (2) are respectively connected to a connecting pipe (5), the connecting pipe (5) is connected to a connector (6), and the connector (6) is connected to the pipe being measured.

3. The electronic differential pressure level gauge according to claim 2, characterized in that, The measured liquid level (7) in the pipeline is located between the two joints (6).

4. The electronic differential pressure level gauge according to claim 1, characterized in that, It also includes a fixed bracket (3), which is detachably connected to the main pressure transmitter (1) and the auxiliary pressure transmitter (2).

5. The electronic differential pressure level gauge according to claim 2, characterized in that, The connecting pipe (5) is an oil-filled capillary tube, and the connector (6) is a flange diaphragm connector.

6. A software synchronization method for an electronic differential pressure level gauge, applied to the electronic differential pressure level gauge as described in any one of claims 1-5, characterized in that, include: The main pressure transmitter sends a first synchronization frame, and the pressure value storage area of ​​the main pressure transmitter points from the first main storage area to the second main storage area. The auxiliary pressure transmitter receives the first synchronization frame, and the pressure value storage area of ​​the auxiliary pressure transmitter points from the first auxiliary storage area to the second auxiliary storage area. The auxiliary pressure transmitter sends the pressure value stored in the first auxiliary storage area to the main pressure transmitter; The main pressure transmitter receives the pressure value stored in the first auxiliary storage area; The main pressure transmitter processes the pressure values ​​stored in the first main storage area and the pressure values ​​stored in the first auxiliary storage area to obtain the first differential pressure value. The first differential pressure value is converted into liquid level to obtain the measured liquid level in the first pipeline.

7. The electronic differential pressure level gauge software synchronization method according to claim 6, characterized in that, The method further includes: The main pressure transmitter sends a second synchronization frame, and the pressure value storage area of ​​the main pressure transmitter points from the second main storage area to the first main storage area; The auxiliary pressure transmitter receives the second synchronization frame, and the pressure value storage area of ​​the auxiliary pressure transmitter points from the second auxiliary storage area to the first auxiliary storage area. The auxiliary pressure transmitter sends the pressure value stored in the second auxiliary storage area to the main pressure transmitter; The main pressure transmitter receives the pressure value stored in the second auxiliary storage area; The main pressure transmitter processes the pressure values ​​stored in the second main storage area and the pressure values ​​stored in the second auxiliary storage area to obtain the second differential pressure value; The second differential pressure value is converted into liquid level to obtain the measured liquid level in the second pipeline.

8. The electronic differential pressure level gauge software synchronization method according to claim 6, characterized in that, The synchronization count values ​​of the main pressure transmitter and the auxiliary pressure transmitter are periodically reset to zero. The main pressure transmitter resets to zero when sending the synchronization frame, and the auxiliary pressure transmitter resets to zero when receiving the synchronization frame.

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