Testing device and method for communication assembly of certain type of consumption component

Abstract

The invention relates to the technical field of equipment circuit board detection, in particular to a testing device and method for a communication assembly of a certain type of consumption component, and the testing device comprises a power supply and power indication circuit, a 422 communication circuit, a 429 communication circuit, an interconnection circuit, and a tested circuit board interface circuit. The testing method comprises the following steps: preparing before testing; performing a 429 communication circuit test; and performing a 422 communication circuit test. The invention provides a device and a method for testing a communication assembly of a certain type of consumption component, which can realize rapid fault location of a communication assembly board, greatly reduce waste in the production process, save resources and reduce cost. And the structure is simple, the work is reliable, the applicability is high, and the practicability is very good.

Description

Technical Field

[0001] The invention relates to the technical field of equipment circuit board detection, in particular to a testing device and method for a certain type of consumption component communication assembly. Background Art

[0002] The main function of the communication assembly circuit board is to realize the transmission and communication of serial data of ARINC429 bus protocol and RS422 protocol, and to play a bridge role in each terminal node of the consumer component bus system network. Its abnormal function will directly cause the consumer component to work abnormally.

[0003] The existing communication assembly is tested by aviation airborne detection equipment adapted for the product. This method has the following disadvantages: (1) The detection items of the aviation airborne detection equipment cover all product functions and the test cycle is long; (2) The detection device can only perform SRU-level repairs, that is, it can only locate the fault on the circuit board, and cannot locate the fault at the component level. Replacing the circuit board will greatly increase the maintenance cost; (3) Since the circuit board needs to be installed in the airborne product under test and all ports of the circuit board need to be installed in place in the product during the entire detection process, it is impossible to collect signals and test the circuit board inside the consumable component, which makes troubleshooting more difficult. Based on this, the present invention proposes a test device and method for a certain type of consumable component communication assembly, which can be separated from the entire airborne equipment for separate testing, thereby performing circuit board testing and fault diagnosis. Summary of the invention

[0004] In order to solve the above technical problems, the present invention proposes a testing device and method for a certain type of consumption component communication assembly.

[0005] The technical problem to be solved by the present invention is achieved by adopting the following technical solutions:

[0006] A test device for a certain type of consumption component communication assembly, comprising:

[0007] The power supply and power indication circuit connects the external power module and the interface circuit of the circuit board under test, and is used to power the circuit board under test, providing three DC power signals, namely +15V, -15V, and +5V;

[0008] The 422 communication circuit includes four transmitters and four receivers, which are connected to the external medium and low frequency maintenance and support test platform and the interface circuit of the circuit board under test, and are used to perform the 422 communication circuit test on the circuit board under test;

[0009] A 429 communication circuit is connected to the interconnection circuit and the interface circuit of the circuit board under test, and is used to perform a 429 communication test on the circuit board under test;

[0010] An interconnection circuit, connecting an external test resource with a circuit board under test, and an interface circuit, for connecting an external test resource with a circuit board under test;

[0011] The circuit board under test interface circuit is used to connect the entire test device with the circuit board under test.

[0012] As a further improvement of the present invention, the interface circuit of the circuit board under test includes pin A01, pin A03, pin A04, pin A23, pin A25, pin B01, pin B07, pin B08, pin B09, pin B10, pin B11, pin B12, pin B13, pin B14, pin B19, pin B23, pin B25, pin C01, pin C23, and pin C25.

[0013] As a further improvement of the present invention, the power supply and power indication circuit includes pin A2, pin B1, and pin B3, wherein pin A2 corresponds to a -15V power signal, pin B1 corresponds to a +15V power signal, and pin B3 corresponds to a +5V power signal;

[0014] Pin A2 is respectively connected to pin A23, pin B23, and pin C23 in the interface circuit of the circuit board under test;

[0015] Pin B1 is respectively connected to pin A25, pin B25, and pin C25 in the interface circuit of the circuit board under test;

[0016] Pin B3 is respectively connected to pin A01, pin B01, and pin C01 in the interface circuit of the circuit board under test.

[0017] As a further improvement of the present invention, the four transmitters on the 422 communication circuit all include pin 3, pin 5 and pin 6, pin 3 is respectively connected to pin B07, pin B09, pin B11 and pin B13 in the interface circuit of the circuit board under test, and pin 5 and pin 6 are respectively connected to an external medium and low frequency maintenance support test platform.

[0018] As a further improvement of the present invention, the four receivers on the 422 communication circuit all include pin 2, pin 7 and pin 8, pin 2 is respectively connected to pin B08, pin B10, pin B12, and pin B14 in the interface circuit of the circuit board under test, and pin 7 and pin 8 are respectively connected to an external medium and low frequency maintenance support test platform.

[0019] As a further improvement of the present invention, the 429 communication circuit includes pin B23 and pin B24, pin B23 is respectively connected to pin A03 and the interconnection circuit in the interface circuit of the circuit board under test, and pin B24 is respectively connected to pin A04 and the interconnection circuit in the interface circuit of the circuit board under test.

[0020] As a further improvement of the present invention, the interconnection circuit includes connectors CZ2 and CZ3, the connector CZ2 includes pins A21, E17, E21, E23, and E25, and the connector CZ3 includes pins E01, E03, E05, E07, D01, and D03;

[0021] Pin A21 on connector CZ2 is connected to pin B19 in the interface circuit of the circuit board under test, pin E17 on connector CZ2 is connected to pin E01 on connector CZ3, pin E21 on connector CZ2 is connected to pin E03 on connector CZ3, pin E23 on connector CZ2 is connected to pin E05 on connector CZ3, pin E25 on connector CZ2 is connected to pin E07 on connector CZ3, pin D01 on connector CZ3 is connected to pin B23 on the 429 communication circuit, and pin D03 on connector CZ3 is connected to pin B24 on the 429 communication circuit.

[0022] A method for testing a certain type of consumable component communication assembly, using the above-mentioned testing device for a certain type of consumable component communication assembly, comprises the following steps:

[0023] Step 1: Preparation before testing:

[0024] The power supply module on the medium and low frequency maintenance and support test platform is connected to the power supply and power indication circuit and the interface of the circuit board under test, the matrix switch module and the relay module are connected to the interconnection circuit, the multi-serial port communication interface module is connected to the 422 communication circuit and the interface of the circuit board under test, the ARINC429 bus communication interface module is connected to the 429 communication circuit and the interface of the circuit board under test, the arbitrary noise generator is connected to the interface of the board under test, the discrete IO module is connected to the interface of the circuit board under test, and the power supply and power indication circuit supplies power to the circuit board under test;

[0025] Step 2: Test the 429 communication circuit:

[0026] The arbitrary noise generator is a square wave with a clock output frequency of 1MHz, a peak-to-peak value of 5V, a DC bias of 2.5V, and a duty cycle of 50% for the clock end of the 429 bus control chip. The discrete IO module applies excitation to the 429 bus control chip through the circuit board port in sequence. At the same time, an oscilloscope is used to collect the 429 output signal waveform and compare it with the standard output signal to verify whether there is any abnormality in the 429 communication sending function;

[0027] Step 3: Test the 422 communication circuit:

[0028] Eight-way 422 communication circuit, four channels are transmitters, four channels are receivers, and the serial port settings of all ports are consistent: the baud rate is 115200bps, 8 data bits, 1 stop bit, odd parity, test the four-way receivers, and verify the correctness of the sending and receiving process, test the four-way transmitters, and verify the correctness of the sending and receiving process.

[0029] As a further improvement of the present invention, the four-way receiver is tested as follows: a differential 422 signal is sent to a 422 transmitter using an AMC5214B communication module, and after being processed by the 422 transmitter, a TTL level signal is output, which is then converted into a 422 differential signal after level conversion by a 422 communication circuit on a detection device, and the 422 signal is collected on the same channel using an AMC5214 communication module, and the correctness of the receiving and sending process is verified by comparing the receiving and sending data.

[0030] As a further improvement of the present invention, the four-way transmitter is tested as follows: a differential 422 signal is sent using an AMC5214B communication module, which is converted into a TTL level signal after level conversion by a 422 communication circuit on a detection device, and the signal is sent to a 422 transmitter on a circuit board under test; after receiving the TTL level signal, the 422 transmitter converts it into a 422 differential signal; the 422 signal is collected using the same channel of an AMC5214 communication module, and the correctness of the receiving and sending process is verified by comparing the receiving and sending data.

[0031] The beneficial effects of the present invention are:

[0032] The present invention provides a testing device and method for a certain type of consumption component communication assembly, which can realize rapid fault location of the communication assembly board, greatly reduce waste in the production process, save resources, and reduce costs; and has a simple structure, reliable operation, strong applicability, and good practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] The present invention is further described below in conjunction with the accompanying drawings and embodiments:

[0034] Figure 1 It is a schematic diagram of the connection between the test device and external equipment;

[0035] Figure 2 Circuit diagram for power supply and power indication circuit;

[0036] Figure 3 It is a circuit diagram of a four-way transmitter circuit in a 422 communication circuit;

[0037] Figure 4 It is a circuit diagram of a four-way receiver circuit in a 422 communication circuit;

[0038] Figure 5Circuit diagram of the AMC5214 module on the external medium and low frequency maintenance and test platform;

[0039] Figure 6 A circuit diagram of a 429 communication circuit;

[0040] Figure 7 A circuit diagram for interconnecting circuits;

[0041] Figure 8 It is the circuit diagram of the connector CZ2 in the interconnection circuit;

[0042] Fig. 9 It is the circuit diagram of connector CZ3 in the interconnection circuit;

[0043] Fig.10 This is the circuit diagram of the interface circuit of the circuit board under test. DETAILED DESCRIPTION

[0044] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described below with reference to the accompanying drawings and embodiments.

[0045] like Figure 1 As shown, a test device for a certain type of consumption component communication assembly includes a power supply and power indication circuit, a 422 communication circuit, a 429 communication circuit, an interconnection circuit, and a circuit board interface circuit under test.

[0046] The circuit diagram of the interface circuit of the circuit board under test is as follows: Fig.10 As shown, it is mainly used to connect the circuit board under test and the entire test device. The interface circuit of the circuit board under test includes pin A01, pin A03, pin A04, pin A23, pin A25, pin B01, pin B07, pin B08, pin B09, pin B10, pin B11, pin B12, pin B13, pin B14, pin B19, pin B23, pin B25, pin C01, pin C23, and pin C25.

[0047] The circuit diagram of the power supply and power indication circuit is as follows Figure 2 As shown. Connect the external power module to the interface circuit of the circuit board under test, used to power the circuit board under test, and provide three DC power signals, respectively +15V, -15V, +5V. It includes pin A2, pin B1, and pin B3. Pin A2 corresponds to -15V power signal, pin B1 corresponds to +15V power signal, and pin B3 corresponds to +5V power signal; pin A2 is respectively connected to pin A23, pin B23, and pin C23 in the interface circuit of the circuit board under test; pin B1 is respectively connected to pin A25, pin B25, and pin C25 in the interface circuit of the circuit board under test; pin B3 is respectively connected to pin A01, pin B01, and pin C01 in the interface circuit of the circuit board under test.

[0048] The circuit diagram of the 422 communication circuit is as follows Figure 3 to Figure 4 As shown. It includes four transmitters and four receivers, connecting the external medium and low frequency maintenance and support test platform with the interface circuit of the circuit board under test, and is used to perform 422 communication circuit testing on the circuit board under test. The circuit diagram of the AMC5214 module on the external medium and low frequency maintenance and support test platform is shown in Figure 5 As shown, it includes pin 1, pin 2, pin 6, pin 7, pin 11, pin 12, pin 16, pin 17, pin B03, pin B04, pin B08, pin B09, pin B13, pin B14, pin B18, and pin B19.

[0049] The four transmitters on the 422 communication circuit all include pin 3, pin 5 and pin 6. Pin 3 on the four transmitters are respectively connected to pin B07, pin B09, pin B11 and pin B13 on the interface circuit of the circuit board under test; pin 5 on the four transmitters are respectively connected to pin B03, pin B08, pin B13 and pin B18 on the AMC5214 module; pin 6 on the four transmitters are respectively connected to pin B04, pin B09, pin B14 and pin B19 on the AMC5214 module.

[0050] The four-way receiver on the 422 communication circuit includes pin 2, pin 7 and pin 8. Pin 2 on the four-way receiver is respectively connected to pin B08, pin B10, pin B12 and pin B14 on the interface circuit of the circuit board under test; pin 7 on the four-way receiver is connected to pin 2, pin 7, pin 12 and pin 17 on the AMC5214 module; pin 8 on the four-way receiver is connected to pin 1, pin 6, pin 11 and pin 16 on the AMC5214 module.

[0051] The circuit diagram of the 429 communication circuit is as follows Figure 6 As shown. Provide one ARINC429 signal for the circuit board under test. The 429 communication circuit includes pin B23 and pin B24. Pin B23 is respectively connected to pin A03 and the interconnection circuit in the interface circuit of the circuit board under test, and pin B24 is respectively connected to pin A04 and the interconnection circuit in the interface circuit of the circuit board under test.

[0052] In addition to the above test resources, this test device still needs discrete IO, matrix switch, signal generator, oscilloscope, multimeter and other resources, so the interconnection circuit is used to connect the circuit board under test with these boards and equipment interfaces. Figures 7 to 9As shown. It includes connectors CZ2 and CZ3, the connector CZ2 includes pins A21, E17, E21, E23, and E25, and the connector CZ3 includes pins E01, E03, E05, E07, D01, and D03;

[0053] Pin A21 on connector CZ2 is connected to pin B19 in the interface circuit of the circuit board under test, pin E17 on connector CZ2 is connected to pin E01 on connector CZ3, pin E21 on connector CZ2 is connected to pin E03 on connector CZ3, pin E23 on connector CZ2 is connected to pin E05 on connector CZ3, pin E25 on connector CZ2 is connected to pin E07 on connector CZ3, pin D01 on connector CZ3 is connected to pin B23 on the 429 communication circuit, and pin D03 on connector CZ3 is connected to pin B24 on the 429 communication circuit.

[0054] A method for testing a certain type of consumable component communication assembly, using the above-mentioned testing device for a certain type of consumable component communication assembly, comprises the following steps:

[0055] Step 1: Preparation before testing:

[0056] Connect the power module N6702A-01 on the medium and low frequency maintenance support test platform to the power supply and power indication circuit and the interface of the circuit board under test to provide voltage for the detection device and the circuit board under test;

[0057] The matrix switch module AMC2623D-1 and the relay module AMC2616 are connected to the interconnection circuit to switch the test path;

[0058] The multi-serial communication interface module AMC5214B is connected to the 422 communication circuit and the interface of the circuit board under test;

[0059] ARINC429 bus communication interface module AMC5206A is connected to the 429 communication circuit and the interface of the circuit board under test;

[0060] The arbitrary noise generator 33250A is connected to the interface of the board under test to provide a clock signal for the circuit board under test;

[0061] The discrete IO module Pickering40-4012 is connected to the interface of the circuit board under test to provide an excitation signal for the circuit board under test;

[0062] The power supply and power indication circuit supplies power to the circuit board under test.

[0063] Step 2: Test the 429 communication circuit:

[0064] The arbitrary noise generator is a 429 bus control chip whose clock output frequency is 1MHz;

[0065] A square wave with a peak-to-peak value of 5V, a DC bias of 2.5V, and a duty cycle of 50%;

[0066] The discrete IO module applies stimulus to the 429 bus control chip through the circuit board port in the order of Table 1-4 below.

[0067] The first step is to apply the signal shown in Table 1 through discrete IO and write the control word 0x0020.

[0068] Table 1 Write control word 0x0020

[0069] Web Logo Level Web Logo Level ENTX Low BD6 Low / XWSTR Low BD7 Low PL1 high BD8 Low PL2 high BD9 Low BD0 Low BD10 Low BD1 Low BD11 Low BD2 Low BD12 Low BD3 Low BD13 Low BD4 Low BD14 Low BD5 high BD15 Low

[0070] In the second step, apply the signal shown in Table 2 through discrete IO to write the first word 0xAAAA.

[0071] Table 2 Write the first word 0xAAAA

[0072]

[0073]

[0074] The third step is to apply the signal shown in Table 3 through discrete IO to write the second word 0x5555.

[0075] Table 3 writes the second word 0x5555

[0076] Web Logo Level Web Logo Level ENTX Low BD6 high / XWSTR high BD7 Low PL1 high BD8 high PL2 Low BD9 Low BD0 high BD10 high BD1 Low BD11 Low BD2 high BD12 high BD3 Low BD13 Low BD4 high BD14 high BD5 Low BD15 Low

[0077] The fourth step is to apply the signal shown in Table 4 through discrete IO to send the 429 signal. At the same time, use an oscilloscope to collect the waveform of the 429 output signal and compare it with the standard output signal to verify whether there is any abnormality in the 429 communication sending function.

[0078] Table 4 Sending 429 signal

[0079]

[0080]

[0081] Step 3: Perform 422 communication circuit test.

[0082] Eight-way 422 communication circuit, four are transmitters and four are receivers. The serial port settings of all ports are consistent: baud rate is 115200bps, 8 data bits, 1 stop bit, odd parity.

[0083] The AMC5214B module is used to send and receive 422 differential signals to the board under test.

[0084] The test process for the 422 receiver is as follows: Use the AMC5214B communication module to send a differential 422 signal (0x55AA) to the 422 transmitter. After being processed by the 422 transmitter, it outputs a TTL level signal, which is then converted into a 422 differential signal after level conversion by the 422 communication circuit on the detection device. Use the AMC5214 communication module to collect the 422 signal on the same channel, and compare the received and sent data to verify the correctness of the receiving and sending process.

[0085] The test process for the 422 transmitter: Use the AMC5214B communication module to send a differential 422 signal (0x55AA), which is converted into a TTL level signal after level conversion by the 422 communication circuit on the detection device, and sent to the 422 transmitter on the circuit board under test. After receiving the TTL level signal, the 422 transmitter converts it into a 422 differential signal, and uses the AMC5214 communication module to collect the 422 signal on the same channel. By comparing the received and sent data, the correctness of the receiving and sending process can be verified.

[0086] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A test device for a certain type of consumption component communication assembly, characterized in that: include: The power supply and power indication circuit connects the external power module and the interface circuit of the circuit board under test, and is used to power the circuit board under test, providing three DC power signals, namely +15V, -15V, and +5V; The 422 communication circuit includes four transmitters and four receivers, which are connected to the external medium and low frequency maintenance and support test platform and the interface circuit of the circuit board under test, and are used to perform the 422 communication circuit test on the circuit board under test; A 429 communication circuit is connected to the interconnection circuit and the interface circuit of the circuit board under test, and is used to perform a 429 communication test on the circuit board under test; An interconnection circuit, connecting an external test resource with a circuit board under test, and an interface circuit, for connecting an external test resource with a circuit board under test; The circuit board under test interface circuit is used to connect the entire test device with the circuit board under test.

2. A test device for a certain type of consumable component communication assembly according to claim 1, characterized in that: The interface circuit of the circuit board under test includes pin A01, pin A03, pin A04, pin A23, pin A25, pin B01, pin B07, pin B08, pin B09, pin B10, pin B11, pin B12, pin B13, pin B14, pin B19, pin B23, pin B25, pin C01, pin C23, and pin C25.

3. A test device for a certain type of consumable component communication assembly according to claim 2, characterized in that: The power supply and power indication circuit includes pin A2, pin B1, and pin B3. Pin A2 corresponds to a -15V power signal, pin B1 corresponds to a +15V power signal, and pin B3 corresponds to a +5V power signal. Pin A2 is respectively connected to pin A23, pin B23, and pin C23 in the interface circuit of the circuit board under test; Pin B1 is respectively connected to pin A25, pin B25, and pin C25 in the interface circuit of the circuit board under test; Pin B3 is respectively connected to pin A01, pin B01, and pin C01 in the interface circuit of the circuit board under test.

4. A test device for a certain type of consumable component communication assembly according to claim 2, characterized in that: The four transmitters on the 422 communication circuit all include pin 3, pin 5 and pin 6. Pin 3 is respectively connected to pins B07, pin B09, pin B11 and pin B13 in the interface circuit of the circuit board under test, and pin 5 and pin 6 are respectively connected to the external medium and low frequency maintenance support test platform.

5. A test device for a certain type of consumable component communication assembly according to claim 2, characterized in that: The four receivers on the 422 communication circuit all include pin 2, pin 7 and pin 8. Pin 2 is respectively connected to pin B08, pin B10, pin B12 and pin B14 in the interface circuit of the circuit board under test, and pin 7 and pin 8 are respectively connected to the external medium and low frequency maintenance support test platform.

6. A test device for a certain type of consumable component communication assembly according to claim 2, characterized in that: The 429 communication circuit includes a pin B23 and a pin B24, wherein the pin B23 is respectively connected to the pin A03 in the interface circuit of the circuit board under test and the interconnection circuit, and the pin B24 is respectively connected to the pin A04 in the interface circuit of the circuit board under test and the interconnection circuit.

7. A test device for a certain type of consumable component communication assembly according to claim 6, characterized in that: The interconnection circuit includes connectors CZ2 and CZ3, the connector CZ2 includes pins A21, E17, E21, E23, and E25, and the connector CZ3 includes pins E01, E03, E05, E07, D01, and D03; Pin A21 on connector CZ2 is connected to pin B19 in the interface circuit of the circuit board under test, pin E17 on connector CZ2 is connected to pin E01 on connector CZ3, pin E21 on connector CZ2 is connected to pin E03 on connector CZ3, pin E23 on connector CZ2 is connected to pin E05 on connector CZ3, pin E25 on connector CZ2 is connected to pin E07 on connector CZ3, pin D01 on connector CZ3 is connected to pin B23 on the 429 communication circuit, and pin D03 on connector CZ3 is connected to pin B24 on the 429 communication circuit.

8. A method for testing a certain type of consumption component communication assembly, characterized in that: A test device for a certain type of consumable component communication assembly using any one of claims 1 to 7 comprises the following steps: Step 1: Preparation before testing: The power supply module on the medium and low frequency maintenance and support test platform is connected to the power supply and power indication circuit and the interface of the circuit board under test, the matrix switch module and the relay module are connected to the interconnection circuit, the multi-serial port communication interface module is connected to the 422 communication circuit and the interface of the circuit board under test, the ARINC429 bus communication interface module is connected to the 429 communication circuit and the interface of the circuit board under test, the arbitrary noise generator is connected to the interface of the board under test, the discrete IO module is connected to the interface of the circuit board under test, and the power supply and power indication circuit supplies power to the circuit board under test; Step 2: Test the 429 communication circuit: The arbitrary noise generator is a square wave with a clock output frequency of 1MHz, a peak-to-peak value of 5V, a DC bias of 2.5V, and a duty cycle of 50% for the clock end of the 429 bus control chip. The discrete IO module applies excitation to the 429 bus control chip through the circuit board port in sequence. At the same time, an oscilloscope is used to collect the 429 output signal waveform and compare it with the standard output signal to verify whether there is any abnormality in the 429 communication sending function; Step 3: Test the 422 communication circuit: Eight-way 422 communication circuit, four channels are transmitters, four channels are receivers, and the serial port settings of all ports are consistent: the baud rate is 115200bps, 8 data bits, 1 stop bit, odd parity, test the four-way receivers, and verify the correctness of the sending and receiving process, test the four-way transmitters, and verify the correctness of the sending and receiving process.

9. A method for testing a certain type of consumable component communication assembly according to claim 8, characterized in that: The specific steps of testing the four-channel receiver are as follows: Use the AMC5214B communication module to send a differential 422 signal to the 422 transmitter. After being processed by the 422 transmitter, it outputs a TTL level signal, which is then converted into a 422 differential signal after level conversion by the 422 communication circuit on the detection device. Use the AMC5214 communication module to collect the 422 signal on the same channel, and compare the received and sent data to verify the correctness of the receiving and sending process.

10. A method for testing a certain type of consumable component communication assembly according to claim 8, characterized in that: The specific test of the four-channel transmitter is as follows: use the AMC5214B communication module to send a differential 422 signal, which is converted into a TTL level signal after level conversion by the 422 communication circuit on the detection device, and this signal is sent to the 422 transmitter on the circuit board under test. After the 422 transmitter receives the TTL level signal, it is converted into a 422 differential signal. The 422 signal is collected on the same channel of the AMC5214 communication module, and the correctness of the receiving and sending process is verified by comparing the receiving and sending data.

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