Signal acquisition system, monitoring system and monitoring method

Abstract

The invention discloses a signal acquisition system, a monitoring system and a monitoring method, and relates to the field of signal acquisition and monitoring, in the scheme, the monitoring system comprises T differential output type physical quantity detection devices, the output ends of the differential output type physical quantity detection devices are connected in series to form T + 1 output ends, and the T + 1 output ends are connected with T + 1 input ends of an input circuit in the signal acquisition system in a one-to-one correspondence mode; t + 1 output ends of the input circuit are connected with T + 1 target signal input ends of the MUX module in a one-to-one correspondence manner; the MUX module is configured to only gate differential signal output corresponding to the jth path of target signal input end and the (j + 1) th path of target signal input end of the MUX module at any moment so as to carry out differential sampling on the output of the jth differential output type physical quantity detection device. According to the scheme, the integrated ADC chip can maximally support N-1 channel differential signal input, the number and cost of the needed integrated ADC chip are reduced, the relative precision and consistency of multi-channel signal measurement are improved, and the system integration degree is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of signal acquisition and monitoring, and in particular to a signal acquisition system, a monitoring system and a monitoring method. Background Art

[0002] Thermocouples based on the Seebeck effect have the advantages of a wide temperature measurement range, simple structure, and high temperature and high pressure resistance. They are currently widely used in industrial process control and equipment monitoring. Specifically, based on actual application needs, multiple thermocouples are usually required in the control and monitoring process. The output acquisition of multiple thermocouple channels currently mainly includes the following acquisition methods: One approach is the independent channel solution, which configures an independent signal conditioning circuit and analog-to-digital converter for each thermocouple channel. Although this approach can achieve synchronous sampling, as the number of channels to be sampled increases, the hardware cost, power consumption, and circuit area increase linearly, making this solution less economical and less integrated. Another way, which is also the mainstream way at present, is the integrated ADC solution (Analog-to-Digital Converter), which is to use a single chip to integrate MUX (Multiplexer), PGA (Programmable Gain Each thermocouple channel has an independent differential input to the integrated ADC chip. However, with increasing application requirements, such as in high-end injection molding machine control, 10 or even 13 or more temperature acquisition channels are often required. However, this solution is limited by the upper limit of the number of channels in the integrated ADC chip, which currently supports a maximum of 8 differential channels. Therefore, to meet current application requirements, the only solution is to combine multiple integrated ADC chips to meet multi-channel temperature acquisition. The disadvantages of this approach are: first, the high cost of integrated ADC chips, and the use of multiple integrated ADC chips will significantly increase the overall cost. Second, the parameters of the reference voltage source and PGA within different integrated ADC chips vary. For example, the initial error and temperature drift of the PGA often vary. This can lead to systematic deviations in measurement results between different integrated ADC chips, reducing the consistency between channels and hindering high-precision multi-point temperature monitoring. Furthermore, multiple integrated ADC chips often correspond to more complex board-level design and software configuration, increasing development difficulty and potential failure points.

[0003] Therefore, how to provide a more effective multi-channel signal acquisition solution is an urgent problem to be solved. Summary of the Invention

[0004] In view of this, the present invention provides a signal acquisition system, a monitoring system, and a monitoring method, which enable the integrated ADC chip to support a maximum of N-1 channel differential signal inputs, thereby reducing the number of required integrated ADC chips to reduce costs, and improving the consistency of the differential signal inputs between the N-1 channels, thereby improving system integration.

[0005] To solve the above technical problems, the present application provides a signal acquisition system for use in a monitoring system. The monitoring system includes T differential output physical quantity detection devices, wherein the output ends of the T differential output physical quantity detection devices are connected in series to form T+1 output ends. The signal acquisition system includes an input circuit and an integrated ADC chip. The integrated ADC chip includes N signal input interfaces and a MUX module, a PGA module, and an ADC module connected in sequence. The N signal input ends of the MUX module are connected to the N signal input interfaces in a one-to-one correspondence, where N is an integer greater than 2. The T+1 output terminals formed are used for one-to-one connection with the T+1 input terminals of the input circuit, and the T+1 output terminals of the input circuit are used for one-to-one connection with the T+1 target signal input terminals of the MUX module through the T+1 target signal input interface among the N signal input interfaces, where 1≤T≤N-1 and T is an integer; The MUX module is configured to select only the differential signal corresponding to its j-th target signal input terminal and the j+1-th target signal input terminal to be output to the PGA module at any time, so as to differentially sample the output of the j-th differential output type physical quantity detection device, where 1≤j≤T and j is an integer.

[0006] The beneficial effect of this application is that through the above settings, the original The integrated ADC chip with independent differential input of channels can support N-1 channel differential signal input at most, which is especially helpful in the case of more than When collecting signals from multiple channels, the number of required integrated ADC chips is reduced, which helps to reduce costs. In this way, multiple channels share the internal reference voltage source, PGA and ADC module of an integrated ADC chip, which helps to improve the consistency of differential signal input between N-1 channels, avoids the systematic error between channels introduced when using multiple integrated ADC chips, and helps to improve the relative accuracy and consistency of multi-channel physical quantity measurement. Reducing the use of integrated ADC chips and their peripheral necessary circuits also helps to effectively save PCB area and improve system integration.

[0007] Furthermore, the MUX module is specifically configured to use each target signal input terminal as the first target signal input terminal in turn, and use the next target signal input terminal of the first target signal input terminal as the second target signal input terminal, so as to output the differential signal corresponding to the first target signal input terminal and the second target signal input terminal to the PGA module, so as to poll the outputs of T differential output type physical quantity detection devices for differential sampling.

[0008] In this solution, the above-mentioned setting facilitates the automatic polling differential sampling of T differential output type physical quantity detection devices.

[0009] Furthermore, the differential output type physical quantity detection device is a thermocouple.

[0010] Furthermore, the input circuit includes a first resistor, a second resistor and T+1 third resistors; One end of the cth third resistor serves as the cth input end of the input circuit, and the other end serves as the cth output end of the input circuit, where 1≤c≤T+1 and c is an integer; One end of the first resistor is connected to the power supply, and the other end is connected to one end of the first third resistor; One end of the second resistor is grounded, and the other end is connected to one end of the T+1th third resistor.

[0011] Furthermore, the input circuit further includes T fourth resistors; One end of the zth fourth resistor is connected to one end of the zth third resistor, and the other end is connected to one end of the z+1th third resistor, where 1≤z≤T and z is an integer.

[0012] In this solution, the above arrangement helps to ensure that when the external path is not connected, the entire series loop from the power supply to the ground TGND remains conductive.

[0013] Furthermore, the input circuit further includes T first filter capacitors; One end of the zth first filter capacitor is connected to the zth target signal input interface, and the other end is connected to the z+1th target signal input interface.

[0014] Furthermore, the input circuit further includes T+1 second filter capacitors; One end of the sth second filter capacitor is connected to the sth target signal input interface, and the other end is grounded, 1≤s≤T+1 and s is an integer.

[0015] To solve the above technical problems, the present application also provides a monitoring system, comprising T differential output type physical quantity detection devices, and also comprising the signal acquisition system as described above; The output ends of the T differential output type physical quantity detection devices are connected in series to form T+1 output ends, and the formed T+1 output ends are used to connect to the signal acquisition system.

[0016] Furthermore, the monitoring system further includes a processing module; The processing module is connected to the signal acquisition system and is used for configuring the MUX module in the signal acquisition system to receive the output of the corresponding differential output type physical quantity detection device.

[0017] To solve the above technical problems, the present application further provides a monitoring method, which is applied to the monitoring system as described above, and the monitoring method includes: Determining a differential sampling order for T differential output type physical quantity detection devices; The MUX module in the monitoring system is configured according to the differential sampling sequence so as to receive the output of the differential output type physical quantity detection device corresponding to the differential sampling sequence. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings: Figure 1 A schematic structural diagram of a monitoring system including a signal acquisition system provided by the present invention; Figure 2 A schematic structural diagram of another monitoring system including a signal acquisition system provided by the present invention; Figure 3 A schematic diagram of the pin configuration of an integrated ADC chip provided by the present invention; Figure 4 The present invention provides a flow chart of a monitoring method. DETAILED DESCRIPTION

[0019] The core of the present invention is to provide a signal acquisition system, monitoring system and monitoring method, which can enable the integrated ADC chip to support a maximum of N-1 channel differential signal input, which helps to reduce the number of integrated ADC chips required to reduce costs, and helps to improve the consistency of differential signal input between N-1 channels, thereby improving system integration.

[0020] The following will be combined with the accompanying drawings in the embodiments of the present application to clearly describe the technical solutions in the embodiments of the present application. Obviously, the embodiments described are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of this application.

[0021] Please refer to Figure 1 , Figure 1 A schematic structural diagram of a monitoring system including a signal acquisition system provided by the present invention.

[0022] The signal acquisition system is applied to a monitoring system. The monitoring system includes T differential output physical quantity detection devices 1, and the output ends of the T differential output physical quantity detection devices 1 are connected in series to form T+1 output ends. The signal acquisition system includes an input circuit 2 and an integrated ADC chip 3. The integrated ADC chip 3 includes N signal input interfaces 31 and a MUX module 32, a PGA module 33, and an ADC module 34 connected in sequence. The N signal input ends of the MUX module 32 are connected to the N signal input interfaces 31 in a one-to-one correspondence, where N is an integer greater than 2. The T+1 output terminals are used for one-to-one connection with the T+1 input terminals of the input circuit 2, and the T+1 output terminals of the input circuit 2 are used for one-to-one connection with the T+1 target signal input terminals of the MUX module 32 through the T+1 target signal input interface 31 among the N signal input interfaces 31, where 1≤T≤N-1 and T is an integer; The MUX module 32 is configured to select only the differential signal corresponding to its own j-th target signal input terminal and the j+1-th target signal input terminal to be output to the PGA module 33 at any time, so as to differentially sample the output of the j-th differential output type physical quantity detection device 1, where 1≤j≤T and j is an integer.

[0023] In this embodiment, considering that the current integrated ADC chip includes a maximum of 16 signal input interfaces, when each thermocouple channel is independently differentially input to the integrated ADC chip, it can only support a maximum of 8 differential channel inputs. Therefore, when facing the demand for signal acquisition of more thermocouple channels, only multiple integrated ADC chips can be used, which has the problems of high cost, poor consistency between channels and increased system complexity. To this end, the present application provides a signal acquisition system, which can enable an integrated ADC chip 3 with N signal input interfaces 31 to support a maximum of N-1 channel differential signal inputs, thereby realizing low-cost, high-consistency multi-channel physical quantity signal acquisition.

[0024] To expand on this, Figure 1The structural diagram of the monitoring system including the signal acquisition system is shown in the figure with N=16 and T=15 as an example. Specifically, the differential output type physical quantity detection device 1 here can be a detection device with positive and negative differential signal output for detecting physical quantities. Each differential output type physical quantity detection device 1 includes an output positive terminal and an output negative terminal. The output terminals of each differential output type physical quantity detection device 1 described here are connected in series: the output positive terminal of the first differential output type physical quantity detection device 1 is the first output terminal, the output negative terminal of the oth differential output type physical quantity detection device 1 is connected to the output positive terminal of the o+1th differential output type physical quantity detection device 1 to obtain the oth output terminal. o+1 output terminals, the negative output terminal of the T-th differential output type physical quantity detection device 1 serves as the T+1-th output terminal, 1≤o≤T-1 and o is an integer; and it should also be noted that in order to realize the series connection of the output terminals of the T differential output type physical quantity detection devices 1, the following two methods can be adopted: the first method is that the technician first uses wires to complete the above-mentioned series setting to form T+1 output terminals and then connect them one by one with the T+1 input terminals of the input circuit 2; the second method, which is also a simpler, more convenient and more practical method, is as follows Figure 1 As shown, an integrated input circuit 4 is provided, which includes an input circuit 2 and a target wire that enables the output ends of T differential output type physical quantity detection devices 1 to be directly connected in series to form T+1 output ends when T differential output type physical quantity detection devices 1 are connected in sequence. Therefore, the integrated input circuit 4 only needs to provide 2T interfaces for the T differential output type physical quantity detection devices 1 to be connected in sequence. Such a setting is more conducive to the simple and reliable connection of each differential output type physical quantity detection device 1 in actual application, and has a higher degree of integration. Both of the above methods are within the protection scope of this application; in addition, in some embodiments, the differential output type physical quantity detection device 1 can be a thermocouple for detecting temperature, and the positive pole of the thermocouple serves as the output positive end of the differential output type physical quantity detection device 1, and the negative pole of the thermocouple serves as the output negative end of the differential output type physical quantity detection device 1, thereby realizing multi-channel temperature signal acquisition, which can be applied to multi-point temperature monitoring scenarios such as injection molding machines; more specifically, the thermocouple can be a K-type thermocouple.

[0025] More specifically, 1≤T≤N-1 and T is an integer, then the T+1 target signal input interface 31 mentioned here refers to the T+1 signal input interface 31 among the N signal input interfaces 31, and the corresponding signal input end of the MUX module 32 connected to the T+1 target signal input interface 31 is the target signal input end of the MUX module 32; please refer to Figure 2 , Figure 2A structural schematic diagram of another monitoring system provided by the present invention including a signal acquisition system shows a setting schematic diagram taking N=16, T=15, and a differential output type physical quantity detection device 1 as an example of a thermocouple. Similarly, an integrated input circuit 4 is set, which includes an input circuit 2 and a target wire that enables the output ends of T thermocouples to be directly connected in series to form T+1 output ends when T thermocouples are connected in sequence. It can be seen that the positive pole T1+ of the first thermocouple CH1 is connected to the first interface of the integrated input circuit 4, so that the first output end is obtained via the target wire connected to the first interface for connection with the first input end T1 of the input circuit, the negative pole T1- of the first thermocouple CH1 is connected to the second interface of the integrated input circuit 4, and the positive pole T2+ of the second thermocouple CH2 is connected to the third interface of the integrated input circuit 4, so that the second output end is obtained via the target wire connected to the second interface and the third interface for connection with the second input end T2 of the input circuit, and the input circuit 2 The connection at the third input terminal T3 is similarly connected and will not be elaborated here. The negative pole T14- of the fourteenth thermocouple CH14 is connected to the twenty-eighth interface of the integrated input circuit 4, and the positive pole T15+ of the fifteenth thermocouple CH15 is connected to the twenty-ninth interface of the integrated circuit, so as to obtain the fifteenth output terminal for connecting to the fifteenth input terminal T15 of the input circuit via the target wire connected to the twenty-eighth interface and the twenty-ninth interface, and the negative pole T15- of the fifteenth thermocouple CH15 is connected to the thirtieth interface of the integrated input circuit 4, so as to obtain the sixteenth output terminal for connecting to the sixteenth input terminal T16 of the input circuit via the target wire connected to the thirtieth interface, and the first output terminal ADC1 of the input circuit is used to be connected to the first target signal input interface 31 of the integrated ADC chip 3. The second output terminal ADC2, the third output terminal ADC3 and so on can be deduced to the fifteenth output terminal ADC15 and the sixteenth output terminal ADC16. The connection settings can be obtained similarly and will not be elaborated here.

[0026] The integrated ADC chip 3 here supports N-way single-ended input, The MUX module 32 in the integrated ADC chip 3 is an analog multiplexer capable of selecting two from N. In addition, a reference voltage source is integrated into the integrated ADC chip 3. For example, the integrated ADC chip 3 may be a TPC6240 integrated ADC chip, which supports 16 single-ended inputs and 8 independent differential inputs. The MUX module 32 is specifically a 16-select-2 analog multiplexer, the PGA module 33 is specifically an adjustable gain differential amplifier, the ADC module 34 is specifically a 24-bit delta-sigma ADC, and the reference voltage source is a 2.5V voltage source. Figure 3 As shown, Figure 3This is a schematic diagram of the pin configuration of an integrated ADC chip provided by the present invention, and specifically illustrates the TPC6240 integrated ADC chip. Pins ADC1 to ADC16 are signal input interfaces for connecting to the output end of input circuit 2, pin TGND is used for grounding, and the remaining settings are common peripheral circuits of the TPC6240 integrated ADC chip, such as pin REFOUT being grounded via capacitor C10. These are all conventional settings and are not described in detail here.

[0027] The MUX module 32 is configured to select only the differential signal access of one differential output type physical quantity detection device 1 at any time. For example, to collect the output of the first differential output type physical quantity detection device 1, the MUX module 32 only selects its own first target signal input terminal and the second target signal input terminal (corresponding to Figure 2 At this time, the differential signal corresponding to the first output terminal ADC1 and the second output terminal ADC2 is output to the PGA module 33 through the MUX module 32); the positive output terminal of the MUX module 32 is connected to the positive input terminal of the PGA module 33, and the negative output terminal of the MUX module 32 is connected to the negative input terminal of the PGA module 33. In addition, before actually using the system for signal acquisition, the gain of the PGA module 33 needs to be configured. For example, taking the differential output type physical quantity detection device 1 as a thermocouple, the gain can be configured to 64 times so that the input range of the PGA module 33 (e.g., -39.06mV to +39.06mV) covers the expected signal range of the thermocouple output (-2mV to 30mV); when the system is actually used for signal acquisition, the PGA module 33 can amplify the difference between the two single-ended signals output by the MUX module 32 and corresponding to the output of the j-th differential output type physical quantity detection device (i.e., the differential electromotive force of the j-th thermocouple), and then the ADC module 34 performs high-precision quantization for subsequent output.

[0028] It should also be noted that the monitoring system may also include a processor, and the configuration of the MUX module 32 can be controlled by the processor using the SPI bus (Serial Peripheral Interface) to control the internal registers of the integrated ADC chip 3 to achieve channel control. In addition, the SPI bus can also be used to transmit the sampled data output by the ADC module 34, so as to feed it back to the processor for subsequent storage, processing and analysis.

[0029] In addition, in actual applications, if the monitoring system includes L differential output type physical quantity detection devices 1 and L is greater than the total number of signal input interfaces 31 corresponding to an integrated ADC chip 3 (i.e., L>N), every N-1 differential output type physical quantity detection devices 1 can be regarded as a group and each group can use an integrated ADC chip 3 to realize signal acquisition (the remaining differential output type physical quantity detection devices 1 automatically become a group), then each group can save an ADC chip compared to the solution in the prior art, which is beneficial to reducing the cost of the entire system.

[0030] It should also be noted that the method of using discrete components, namely MUX chip, PGA chip and single-channel ADC chip to replace the integrated ADC chip 3 in this application is also within the scope of protection of this application, but this method will reduce the circuit integration and the cost will be higher.

[0031] In addition, according to the above-mentioned series topology setting in this application, it is necessary to ensure that no short circuit occurs between the thermocouples. Therefore, attention should be paid to the selection and wiring design of the thermocouples. In actual applications, a monitoring circuit can be set to detect whether a short circuit occurs between two adjacent thermocouples. The form of the monitoring circuit is not particularly limited here, and it can be flexibly set.

[0032] In summary, this application provides a signal acquisition system, which, through the above settings, enables the original system to only support The integrated ADC chip 3 with independent differential input of the channel can support N-1 channel differential signal input at most (for example, an ADC chip that originally only supports 8 independent differential inputs can support 15 differential inputs by relying on the setting method in this application), which is especially beneficial in the face of more than When acquiring signals from the N-1 channels, the above-mentioned series topology and signal multiplexing setting can reduce the number of required integrated ADC chips 3 (for example, originally two TPC6240 integrated ADC chips 3 were required for 15-channel thermocouple signal acquisition, but now only one TPC6240 integrated ADC chip 3 is needed, and in actual applications, it has been found that this setting can reduce the overall cost of the monitoring system by more than 40%), which is conducive to reducing costs. In this way, all T channels share the internal reference voltage source, PGA and ADC module 34 of an integrated ADC chip 3, which is conducive to improving the consistency of differential signal input between N-1 channels, avoiding the inter-channel systematic error introduced when using multiple integrated ADC chips 3, and improving the relative accuracy and consistency of multi-channel physical quantity measurement; and reducing the use of integrated ADC chips 3 and their peripheral necessary circuits (such as decoupling capacitors, communication interfaces, etc.) also helps to effectively save PCB area and improve system integration. In actual applications, it has been found that this application can reduce the PCB wiring area by about 30%, which is more conducive to compact device design.

[0033] In some embodiments, the MUX module 32 is specifically configured to use each target signal input terminal as the first target signal input terminal in turn, and use the next target signal input terminal of the first target signal input terminal as the second target signal input terminal, so as to output the differential signal corresponding to the first target signal input terminal and the second target signal input terminal to the PGA module 33, so as to poll the outputs of the differentially sampled T differential output type physical quantity detection devices 1.

[0034] Specifically, the above configuration facilitates the implementation of automatic polling differential sampling of T differential output type physical quantity detection devices 1 .

[0035] In some embodiments, the input circuit 2 includes a first resistor R1, a second resistor R2, and T+1 third resistors; One end of the cth third resistor serves as the cth input end of the input circuit 2, and the other end serves as the cth output end of the input circuit 2, where 1≤c≤T+1 and c is an integer; One end of the first resistor R1 is connected to the power supply, and the other end is connected to one end of the first third resistor; One end of the second resistor R2 is grounded, and the other end is connected to one end of the T+1th third resistor.

[0036] Specifically, corresponding to T=15, the input circuit 2 may include sixteen third resistors, such as Figure 2 As shown, it can include a first third resistor R12, a second third resistor R22, a third third resistor R32, and so on to the fifteenth third resistor R152 and the sixteenth third resistor R162. Relying on the above settings, the positive electrode T1+ of the first thermocouple CH1 can be pulled up to the power supply through the first resistor R1, and the negative electrode T15- of the fifteenth thermocouple CH15 can be pulled down to the ground TGND through the second resistor R2.

[0037] More specifically, the input circuit 2 further includes T fourth resistors; One end of the zth fourth resistor is connected to one end of the zth third resistor, and the other end is connected to one end of the z+1th third resistor, where 1≤z≤T and z is an integer.

[0038] Corresponding to Figure 2 The input circuit 2 may include a first fourth resistor R11 , a second fourth resistor R21 , a third fourth resistor R31 , and so on up to a fifteenth fourth resistor R151 .

[0039] It should be noted that the power supply here can be Figure 2The 3.3V DC power supply shown in the figure and the fourth resistors ensure that the entire series circuit from the power supply to ground TGND remains conductive when the external thermocouple is not connected. This configuration provides a bias voltage to ensure that the differential signal level of each input is within the level range of the integrated ADC chip 3. For a differential output physical quantity detection device 1 using a thermocouple, preferably, the resistance of the first resistor R1 can be 4.7MΩ, the resistance of the second resistor R2 can be 4.7MΩ, the resistance of each third resistor can be 1kΩ, and the resistance of each fourth resistor can be 120kΩ.

[0040] In some embodiments, the input circuit 2 further includes T first filter capacitors; One end of the zth first filter capacitor is connected to the zth target signal input interface 31 , and the other end is connected to the z+1th target signal input interface 31 .

[0041] Specifically, each first filter capacitor is used for filtering; corresponding to Figure 2 The input circuit 2 may include a first first filter capacitor C11, a second first filter capacitor C21, a third first filter capacitor C31, and so on until a fifteenth first filter capacitor C151.

[0042] In addition, corresponding to the differential output type physical quantity detection device 1 being a thermocouple, preferably, the capacitance of the first filter capacitor may be 2.2 μF.

[0043] In some embodiments, the input circuit 2 further includes T+1 second filter capacitors; One end of the s-th second filter capacitor is connected to the s-th target signal input interface 31 , and the other end is grounded, where 1≤s≤T+1 and s is an integer.

[0044] Specifically, each second filter capacitor is used for filtering; corresponding to Figure 2 The input circuit 2 may include a first second filter capacitor C12, a second second filter capacitor C22, a third second filter capacitor C32, and so on to a fifteenth second filter capacitor C152 and a sixteenth second filter capacitor C162.

[0045] In addition, corresponding to the differential output type physical quantity detection device 1 being a thermocouple, preferably, the capacitance of the second filter capacitor can be 1 μF.

[0046] As a further illustration of the effectiveness of the technical solution provided by the present application in practical applications, the differential output type physical quantity detection device 1 is taken as a thermocouple, and the preferred setting parameters of each part of the above-mentioned input resistor are described as an example: (1) Analysis of the open circuit voltage (i.e., none of the T+1 input terminals of input circuit 2 are connected): The first resistor R1, each fourth resistor and the second resistor R2 form a series voltage divider with a total resistance of ≈9.4MΩ+15*120kΩ; the voltage drop across each 120kΩ fourth resistor is: V_drop=3.3V*(120kΩ) / (4.7MΩ+4.7MΩ+15*120kΩ)≈35.35mV; ignoring the influence of the high-impedance ADC input, the voltage at the first input terminal T1 of the input circuit 2 is ≈3.3V*(1-4.7MΩ / (4.7MΩ+4.7MΩ+15*120kΩ ))=1.915V; the voltage at the second input terminal T2 ≈ the voltage at the first input terminal T1 - V_drop=1.880V; by analogy, based on a decrease of 35.35mV, the voltage at the fifteenth input terminal T15 ≈1.420V; the voltage at the sixteenth input terminal T16 ≈1.385V. Therefore, the voltage range of the sixteen output terminals (ADC1 to ADC16) of input circuit 2 is: 1.385V~1.915V, which meets the TPC6240 input requirement (0.15V~2.95V).

[0047] (2) Voltage range analysis when connected to a thermocouple: The output signal range of the thermocouple is -2mV~30mV (much smaller than the open-circuit steady-state voltage drop of 35.35mV); the extreme situation analysis of the node at the first input terminal T1 of input circuit 2 is: when all channel inputs are -2mV (minimum value), the voltage at the first input terminal T1 reaches the minimum value, and the theoretical calculated value corresponding to this minimum value is ≈1.635V; when all channels are suspended (maximum value), the voltage at the first input terminal T1 reaches the maximum value = 1.915V (same as the open-circuit state), then it can be concluded that 1.635V≤the voltage at the first input terminal T1≤1.915V. Similarly, 1.385V (corresponding to all channels being suspended)≤the voltage at the sixteenth input The voltage at the input terminal T16 is ≤1.665V (corresponding to a minimum value of -2mV for all channel inputs); and the voltage range at the second input terminal T2 to the fifteenth input terminal T15 does not exceed the voltage range at the first input terminal T1 and the sixteenth input terminal T16. Therefore, the voltage range of all nodes from the first input terminal T1 to the sixteenth input terminal T16 is 1.385V~1.915V; in the steady state, no current flows from the first output terminal ADC1 to the sixteenth output terminal ADC16 of the input circuit 2, and their voltage range is equivalent to the voltage range of all nodes from the first input terminal T1 to the sixteenth input terminal T16, fully meeting the input requirements of the subsequent integrated ADC chip 3.

[0048] (3) Analysis of crosstalk between channels: This application utilizes the configuration of MUX module 32 to ensure that only the differential signal corresponding to one thermocouple is activated at any given time and input to the subsequent PGA module 33. This approach isolates the influence of other channels on the current sampling loop through differential sampling. The influence introduced by the unsampled channel primarily manifests as a change in common-mode voltage. The PGA module 33 in the integrated ADC chip 3 has a high common-mode rejection ratio, effectively suppressing common-mode interference. Consequently, the impact on the differential signal (differential-mode voltage) output by the thermocouple of the currently connected channel is minimal. Furthermore, an actual impact assessment using multi-point temperature detection in an injection molding machine as an example shows that the temperature change rate of the thermocouple is conservatively estimated to be ≤10°C / s. The sensitivity of a K-type thermocouple is approximately 40μV / °C, and the signal slope is ≤0.4mV / s. The common-mode interference generated by the undifferentially sampled channel is ≤0.4mV / s, a magnitude far lower than the inherent noise and interference level of the system, making inter-channel interference negligible. It can be seen that the measured results show that the application solution has no significant difference from the standard dual-chip solution in key performance indicators such as signal measurement accuracy and anti-interference ability, and meets the application requirements.

[0049] It should also be noted that since this application changes from dual-chip parallel acquisition to single-chip polling acquisition, the overall data acquisition rate of the system has been reduced (estimated to be about 50%). However, for typical industrial temperature control scenarios such as injection molding machines (temperature changes are relatively slow, and the sampling rate requirements are usually in the range of several Hz to tens of Hz), this rate can still fully meet the actual application needs.

[0050] As can be seen, the above-mentioned configuration facilitates high-precision acquisition of N-1 channel signals. While maintaining comparable core performance indicators (i.e., accuracy and anti-interference), this application significantly reduces system cost (by approximately 40%) and PCB footprint (by approximately 30%), and improves inter-channel consistency. Although the acquisition rate is reduced and there are requirements for insulation between sensors, these trade-offs are acceptable in the target application scenarios (such as injection molding machine temperature control). Therefore, the solution of the present invention has significant application value and competitive advantages in the field of multi-point temperature monitoring of cost-sensitive industrial equipment.

[0051] The present invention also provides a monitoring system, comprising T differential output type physical quantity detection devices 1, and also comprising the signal acquisition system as described above; The output ends of T differential output type physical quantity detection devices 1 are connected in series to form T+1 output ends, and the T+1 output ends are used to connect to the signal acquisition system.

[0052] For an introduction to the monitoring system provided in this application, please refer to the aforementioned embodiment of the signal acquisition system, which will not be repeated here. Similarly, as described in the aforementioned embodiment, when an integrated input circuit 4 is present in the signal acquisition system, the aforementioned series connection can be achieved by simply connecting the output terminals of the T differential output physical quantity detection devices 1 in sequence to the respective interfaces of the integrated input circuit 4.

[0053] In some embodiments, the monitoring system further comprises a processing module; The processing module is connected to the signal acquisition system and is used for configuring the MUX module 32 in the signal acquisition system to receive the output of the corresponding differential output type physical quantity detection device 1 .

[0054] Specifically, as described above, the processor uses the SPI bus to control the internal registers of the integrated ADC chip 3 to configure the MUX module 32 .

[0055] Please refer to Figure 4 , Figure 4 The present invention provides a flow chart of a monitoring method.

[0056] The monitoring method is applied to the monitoring system as described above, and includes: S11: Determine the differential sampling order for T differential output type physical quantity detection devices 1; S12: The MUX module 32 in the monitoring system is configured according to the differential sampling sequence so as to receive the output of the differential output type physical quantity detection device 1 corresponding to the differential sampling sequence.

[0057] Specifically, the monitoring method can be applied to the processor in the monitoring system; it should also be noted that the differential sampling order here can be the polling differential sampling described above, or it can be sampling performed in other specific sampling orders. There is no special limitation here, and it can be flexibly set according to actual needs.

[0058] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0059] The above-described embodiments represent only a few implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present application. It should be noted that a person skilled in the art could make a number of variations and improvements without departing from the spirit of the present application, and these variations and improvements are all within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the appended claims. The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from the other embodiments. Similar or identical parts between the various embodiments may be referenced to each other. Relational terms such as first and second, etc., are used solely to distinguish one entity or operation from another and do not necessarily require or imply any actual relationship or order between these entities or operations. The terms "comprise," "include," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. Without further constraints, an element defined by the phrase "comprises a" does not exclude the existence of additional identical elements in the process, method, article or apparatus that includes the element.

[0060] Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not limited to the embodiments shown herein, but is to be construed in the widest manner consistent with the principles and novel features disclosed herein.

Claims

1. A signal acquisition system, characterized in that: Applied to a monitoring system, the monitoring system includes T differential output physical quantity detection devices, and the output ends of the T differential output physical quantity detection devices are connected in series to form T+1 output ends; the signal acquisition system includes an input circuit and an integrated ADC chip, the integrated ADC chip includes N signal input interfaces and a MUX module, a PGA module, and an ADC module connected in sequence, and the N signal input ends of the MUX module are connected to the N signal input interfaces in a one-to-one correspondence, where N is an integer greater than 2; The T+1 output terminals formed are used for one-to-one connection with the T+1 input terminals of the input circuit, and the T+1 output terminals of the input circuit are used for one-to-one connection with the T+1 target signal input terminals of the MUX module through the T+1 target signal input interface among the N signal input interfaces, where 1≤T≤N-1 and T is an integer; The MUX module is configured to select only the differential signal corresponding to its j-th target signal input terminal and the j+1-th target signal input terminal to be output to the PGA module at any time, so as to differentially sample the output of the j-th differential output type physical quantity detection device, where 1≤j≤T and j is an integer.

2. The signal acquisition system according to claim 1, wherein: The MUX module is specifically configured to use each target signal input terminal as the first target signal input terminal in turn, and use the next target signal input terminal of the first target signal input terminal as the second target signal input terminal, so as to output the differential signal corresponding to the first target signal input terminal and the second target signal input terminal to the PGA module, so as to poll the outputs of T differential output type physical quantity detection devices for differential sampling.

3. The signal acquisition system according to claim 1, wherein: The differential output type physical quantity detection device is a thermocouple.

4. The signal acquisition system according to any one of claims 1 to 3, wherein: The input circuit includes a first resistor, a second resistor and T+1 third resistors; One end of the cth third resistor serves as the cth input end of the input circuit, and the other end serves as the cth output end of the input circuit, where 1≤c≤T+1 and c is an integer; One end of the first resistor is connected to the power supply, and the other end is connected to one end of the first third resistor; One end of the second resistor is grounded, and the other end is connected to one end of the T+1th third resistor.

5. The signal acquisition system according to claim 4, wherein: The input circuit further includes T fourth resistors; One end of the zth fourth resistor is connected to one end of the zth third resistor, and the other end is connected to one end of the z+1th third resistor, where 1≤z≤T and z is an integer.

6. The signal acquisition system according to claim 5, wherein: The input circuit further includes T first filter capacitors; One end of the zth first filter capacitor is connected to the zth target signal input interface, and the other end is connected to the z+1th target signal input interface.

7. The signal acquisition system according to claim 5, wherein: The input circuit also includes T+1 second filter capacitors; One end of the sth second filter capacitor is connected to the sth target signal input interface, and the other end is grounded, 1≤s≤T+1 and s is an integer.

8. A monitoring system, characterized in that: comprising T differential output type physical quantity detection devices, and also comprising the signal acquisition system according to any one of claims 1 to 7; The output ends of the T differential output type physical quantity detection devices are connected in series to form T+1 output ends, and the formed T+1 output ends are used to connect to the signal acquisition system.

9. The monitoring system according to claim 8, wherein: The monitoring system further includes a processing module; The processing module is connected to the signal acquisition system and is used for configuring the MUX module in the signal acquisition system to receive the output of the corresponding differential output type physical quantity detection device.

10. A monitoring method, characterized in that: Applied to the monitoring system according to claim 8 or 9, the monitoring method comprises: Determining a differential sampling order for T differential output type physical quantity detection devices; The MUX module in the monitoring system is configured according to the differential sampling sequence so as to receive the output of the differential output type physical quantity detection device corresponding to the differential sampling sequence.

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