Serial port expansion circuit and signal control system

Abstract

The utility model discloses a serial port expansion circuit and a signal control system, and belongs to the technical field of power electronics, the circuit comprises a multiplexer, a first level conversion module used for converting an RS232 signal into a target digital signal, and a plurality of second level conversion modules used for converting the target digital signal into a serial port communication signal; wherein the input end of the multiplexer is connected with an RS232 interface of the industrial control board through the first level conversion module, the control end of the multiplexer is connected with an IO interface of the industrial control board, and each output end of the multiplexer is connected with one second level conversion module. Through the circuit, not only can the complexity of expansion of the RS232 interface on the industrial control board be reduced, but also the cost input required by expansion of the RS232 interface on the industrial control board can be reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of power electronics, and particularly relates to a serial port expansion circuit and a signal control system. Background Art

[0002] Due to the excellent characteristics of industrial control boards such as earthquake resistance, interference resistance, and high temperature resistance, they are widely used in various industrial scenarios. However, the number of RS232 interfaces provided on industrial control boards is limited. In some cases where a large number of peripheral devices need to be connected to the industrial control board, it is necessary to expand the RS232 interfaces on the industrial control board.

[0003] In the prior art, a dedicated serial port expansion chip or a single-chip microcomputer is usually used to expand the RS232 interfaces on the industrial control board. Among them, when using a serial port expansion chip to expand the RS232 interfaces on the industrial control board, it is necessary to develop and encapsulate the communication protocol of the industrial control board according to the protocol format of the serial port expansion chip. This not only results in a slow communication rate of the serial port expansion chip, but also requires reconfiguration of relevant devices on the industrial control board when the industrial control board controls peripheral devices with different rates, and the logic control is complex and cumbersome. When using a single-chip microcomputer to expand the RS232 interfaces on the industrial control board, it is necessary to develop the communication protocol used by the single-chip microcomputer according to the communication standard of the industrial control board. The development process is not only complex, but also costly. Currently, there is no relatively effective solution to this technical problem.

[0004] Therefore, how to reduce the expansion cost of the serial port number of the industrial control board without modifying the devices in the industrial control board and the serial port expansion circuit is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Utility Model

[0005] In view of this, the purpose of the utility model is to provide a serial port expansion circuit and a signal control system to solve the technical problems that the cost is high and the devices in the industrial control board or the serial port expansion circuit need to be modified when expanding the RS232 interfaces on the industrial control board in the prior art. The specific solutions are as follows:

[0006] To solve the above technical problems, the utility model provides a serial port expansion circuit, including: a multiplexer, a first level conversion module for converting RS232 signals into target digital signals, and a plurality of second level conversion modules for converting the target digital signals into serial port communication signals;

[0007] Among them, the input end of the multiplexer is connected to the RS232 interface of the industrial control board through the first level conversion module, the control end of the multiplexer is connected to the IO interface of the industrial control board, and each output end of the multiplexer is connected to a second level conversion module.

[0008] Preferably, it further includes: an optocoupler;

[0009] Among them, the control end of the multiplexer is connected to the IO interface of the industrial control board through the optocoupler.

[0010] Preferably, the first level conversion module is specifically a module for converting the RS232 signal into a TTL level signal, and the second level conversion module is specifically a module for converting the TTL level signal into the RS232 signal.

[0011] Preferably, both the first level conversion module and the second level conversion module are modules built by logic gate circuits.

[0012] Preferably, both the first level conversion module and the second level conversion module are modules built by triodes.

[0013] Preferably, the first level conversion module is specifically a module for converting the RS232 signal into a TTL level signal, and the second level conversion module is specifically a module for converting the TTL level signal into an RS485 signal.

[0014] Preferably, it further includes:

[0015] A power supply module that is connected to the multiplexer, the first level conversion module, and the second level conversion module, and is used to supply power to the multiplexer, the first level conversion module, and the second level conversion module.

[0016] Preferably, the multiplexer is specifically a multi-channel analog switch chip.

[0017] Preferably, a BBM delay module is provided on the multi-channel analog switch chip.

[0018] Correspondingly, the present invention further provides a signal control system, including a serial port expansion circuit as disclosed above.

[0019] Beneficial effects: In the serial port expansion circuit provided by the present utility model, a multiplexer, a first level conversion module for converting RS232 signals into target digital signals, and a plurality of second level conversion modules for converting target digital signals into serial port communication signals are provided. Among them, the input end of the multiplexer is connected to the RS232 interface of the industrial control board through the first level conversion module, the control end of the multiplexer is connected to the IO interface of the industrial control board, and each output end of the multiplexer is connected to a second level conversion module.

[0020] Compared with the prior art, in the present application, only one multiplexer, one first level conversion module, and a plurality of second level conversion modules can be used to achieve the purpose of expanding the RS232 interface on the industrial control board. In this expansion circuit, neither the industrial control board nor the devices in the serial port expansion circuit need to be modified, which can reduce the complexity of expanding the RS232 interface on the industrial control board. Moreover, the manufacturing costs of the multiplexer, the first level conversion module, and the second level conversion module are low, so the cost investment required for expanding the RS232 interface on the industrial control board can be significantly reduced. Correspondingly, a signal control system provided by the present utility model also has the above beneficial effects. Description of the Drawings

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present utility model or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present utility model. For those of ordinary skill in the art, other drawings can be obtained according to the provided drawings without creative efforts.

[0022] Figure 1 Schematic diagram when the industrial control board controls the peripheral devices of the in vitro diagnostic instrument;

[0023] Figure 2 Structural diagram of a serial port expansion circuit provided by an embodiment of the present utility model;

[0024] Figure 3 Structural diagram of another serial port expansion circuit provided by an embodiment of the present utility model;

[0025] Figure 4 Structural diagram of another serial port expansion circuit provided by an embodiment of the present utility model;

[0026] Figure 5 Structural diagram of another serial port expansion circuit provided by an embodiment of the present utility model;

[0027] Figure 6The structural diagram of another serial port expansion circuit provided by an embodiment of the present utility model;

[0028] Figure 7 The structural diagram of another serial port expansion circuit provided by an embodiment of the present utility model;

[0029] Figure 8 The structural diagram of another serial port expansion circuit provided by an embodiment of the present utility model.

[0030] Reference numerals:

[0031] 101 - Industrial control board; 01 - 232 to 485 device; 02 - Voice broadcaster; 03 - Printer; 04 - RFID board; 05 - Vision board; 06 - Centrifuge; 07 - Barcode scanner; 10 - Serial port expansion circuit; 11 - First level conversion module; 12 - Multiplexer; 13 - Second level conversion module; 131 - RS232 interface; 14 - Optocoupler; 15 - Power supply module. Detailed implementation manners

[0032] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.

[0033] Industrial control boards are widely used in some medium and large industrial control systems. For example, in the centralized pre - processing module of in - vitro diagnostic instruments, industrial control boards are often used to control multiple peripheral devices outside the in - vitro diagnostic instruments.

[0034] Please refer to Figure 1 , Figure 1 which is a schematic diagram when the industrial control board controls the peripheral devices of the in - vitro diagnostic instrument. In Figure 1 , there are an industrial control board 101, a 232 - to - 485 device 01, a voice broadcaster 02, a printer 03, an RFID board 04, a vision board 05, a centrifuge 06, and a barcode scanner 07. The industrial control board 101 needs to control the barcode scanner 07, the centrifuge 06, the vision board 05, the RFID board 04, the printer 03, the voice broadcaster 02, and the 232 - to - RS485 device 01 through the RS232 interface.

[0035] Among them, the barcode scanner 07 is used to identify the barcodes of the sample racks / sample tubes, and transmit the barcode information of the sample tubes to the controller of the in vitro diagnostic instrument through the RS232 interface on the industrial control board 101; the centrifuge 06 is used to separate the serum of the blood sample, and control the start and stop of the centrifuge 06 through the RS232 interface on the industrial control board 101; the vision board 05 is used to detect the quality of the centrifuged serum, and transmit the quality detection result of the serum to the controller of the in vitro diagnostic instrument through the RS232 interface on the industrial control board 101; the RFID board 04 is used to locate and track the sample racks / sample carriers, and transmit the information of the sample racks / sample carriers to the controller of the in vitro diagnostic instrument through the RS232 interface on the industrial control board 101; the printer 03 is used to print the barcodes or detection results pasted on the test tubes, and transmit the relevant printing information of the printer 03 through the RS232 interface on the industrial control board 101; the voice broadcaster 02 is used to broadcast the current operating status of the in vitro diagnostic instrument, and broadcast the current operating status of the in vitro diagnostic instrument through the RS232 interface on the industrial control board 101; the RS232 to RS485 device 01 is used to expand RS485 devices, for example: expand and connect a gripper motor conforming to the RS485 standard on the industrial control board 101, and implement modbus communication through the RS232 interface on the industrial control board 101. Moreover, in practical applications, it is also necessary to reserve RS232 interfaces on the industrial control board 101, and use the RS232 interfaces to debug other peripheral devices.

[0036] If it is in a large in vitro diagnostic instrument, multiple barcode scanners 07, RFID boards 04, vision boards 05, etc. are usually connected to the industrial control board 101, and currently only 8 RS232 interfaces are provided on the industrial control board 101. At this time, the demand for the number of RS232 interfaces in the industrial control board 101 of the in vitro diagnostic instrument is much greater than the number of originally provided RS232 interfaces on the industrial control board 101. In this case, it is necessary to expand the number of serial ports on the industrial control board 101. If a dedicated serial port expansion chip or a single-chip microcomputer is used to expand the number of RS232 interfaces on the industrial control board 101, not only the industrial control board or the serial port expansion chip needs to be modified, but also a relatively high development cost needs to be invested.

[0037] To solve this technical problem, in this application, a new type of serial port expansion circuit is provided, which is used to expand the RS232 interfaces on the industrial control board, without the need to modify the industrial control board and the components in the expansion circuit, and without a high development cost.

[0038] Please refer to Figure 2 , Figure 2The figure shows a structural diagram of a serial port expansion circuit provided by an embodiment of the present utility model. The serial port expansion circuit 10 includes: a multiplexer 12, a first level conversion module 11 for converting an RS232 signal into a target digital signal, and a plurality of second level conversion modules 13 for converting the target digital signal into a serial port communication signal.

[0039] Among them, the input end of the multiplexer 12 is connected to the RS232 interface of the industrial control board 101 through the first level conversion module 11. The control end of the multiplexer 12 is connected to the IO interface of the industrial control board 101. Each output end of the multiplexer 12 is connected to a second level conversion module 13.

[0040] In the serial port expansion circuit 10 provided by this embodiment, there is one multiplexer 12, one first level conversion module 11, and a plurality of second level conversion modules 13. When the input end of the multiplexer 12 is connected to the RS232 interface of the industrial control board 101 through the first level conversion module 11, the first level conversion module 11 can convert the RS232 signal output by the industrial control board 101 into a target digital signal recognizable by the subsequent circuit. At this time, the multiplexer 12 can recognize the RS232 signal output by the industrial control board 101.

[0041] When the control end of the multiplexer 12 is connected to the IO interface of the industrial control board 101, the multiplexer 12 can determine which output path of the multiplexer 12 needs to be conducted through the pre-set logic. At the same time, since each output end of the multiplexer 12 is connected to a second level conversion module 13, and the second level conversion module 13 can convert the target digital signal into a serial port communication signal. At this time, by combining the multiplexer 12 and a plurality of second level conversion modules 13, the expansion of the RS232 interface on the industrial control board 101 can be realized. Among them, the serial port communication signal can be either an RS232 signal or an RS485 signal. That is, through the second level conversion module 13 in the serial port expansion circuit, the purpose of expanding the RS232 interface on the industrial control board 101 into an RS232 interface can be achieved, and the purpose of expanding the RS232 interface on the industrial control board 101 into an RS484 interface can also be achieved.

[0042] Specifically, in practical applications, the multiplexer 12 can be set as a double - pole eight - throw analog switch chip, a double - pole four - throw analog switch chip, a single - pole eight - throw analog switch chip, etc. Please refer to Figure 3 , Figure 3 The figure shows a structural diagram of another serial port expansion circuit provided by an embodiment of the present utility model. In Figure 3In the serial port expansion circuit shown, the multiplexer 12 is set as a double - pole four - throw analog switch chip, and the serial port communication signal is set as the RS232 signal. At this time, 4 RS232 interfaces can be expanded by using this serial port expansion circuit. It should be noted that the RS232 interface 131 is set on the second - level conversion module 13. Here, for the convenience of those skilled in the art to better understand the implementation principle of the technical solution described in this application, the RS232 interface 131 is separately connected to the subsequent stage of the second - level conversion module 13. In addition, in practical applications, this serial port expansion circuit can be assembled near the industrial control board 101 to reduce communication interference.

[0043] Compared with the prior art, in this application, only one multiplexer, one first - level conversion module, and multiple second - level conversion modules can be used to achieve the purpose of expanding the RS232 interfaces on the industrial control board. In this expansion circuit, neither the industrial control board needs to be modified nor the components in the serial port expansion circuit need to be modified, which can reduce the complexity when expanding the RS232 interfaces on the industrial control board. Moreover, the manufacturing costs of the multiplexer, the first - level conversion module, and the second - level conversion module are low, so the cost investment required for expanding the RS232 interfaces on the industrial control board can be significantly reduced.

[0044] Based on the above - mentioned embodiments, this embodiment further explains and optimizes the technical solution. As a preferred implementation manner, the above - mentioned circuit further includes: an optocoupler;

[0045] Among them, the control end of the multiplexer is connected to the IO interface of the industrial control board through the optocoupler.

[0046] In practical applications, an optocoupler can also be set on the serial port expansion circuit, and the optocoupler can be used to improve the anti - interference performance of the serial port expansion circuit. Please refer to Figure 4 , Figure 4 which is the structural diagram of another serial port expansion circuit provided by the embodiment of the present invention. In the serial port expansion circuit shown in Figure 4 , an optocoupler 14 is connected between the control end of the multiplexer 12 and the IO interface of the industrial control board 101. Among them, the RS232 signal output by the industrial control board 101 through the RS232 interface is a ± 12V level signal, which has strong anti - interference performance and the signal can be transmitted for more than ten meters. After the IO signal output by the industrial control board 101 through the IO interface is driven by the optocoupler 14, the IO signal can be transmitted over a longer distance, and the transmission delay is about several hundred microseconds. In this way, the anti - interference performance of the serial port expansion circuit can be further improved.

[0047] Obviously, through the technical solution provided by this embodiment, the anti-interference performance of the serial port expansion circuit can be further improved, and the stability and reliability of the serial port expansion circuit during operation can be ensured.

[0048] Based on the above embodiment, this embodiment further explains and optimizes the technical solution. As a preferred implementation manner, the first level conversion module 11 is specifically a module that converts RS232 signals into TTL level signals, and the second level conversion module 13 is specifically a module that converts TTL level signals into RS232 signals.

[0049] In this embodiment, the first level conversion module 11 can be set as a module that converts RS232 signals into TTL level signals, and the second level conversion module 13 can be set as a module that converts TTL level signals into RS232 signals.

[0050] Because the heat loss of TTL level signals is relatively low, they can be directly connected to integrated circuits without using expensive line driver and receiver circuits, which can further reduce the cost investment required for the serial port expansion circuit. Moreover, TTL level signals usually also have a relatively high current driving ability and can provide sufficient current to drive the subsequent circuit, thereby enabling the serial port expansion circuit to meet the requirements of high-speed data transmission.

[0051] In practical applications, logic gate circuits can be used to build the first level conversion module 11 and the second level conversion module 13, or transistors can be used to build the first level conversion module 11 and the second level conversion module 13, which can improve the flexibility and diversity in building the first level conversion module 11 and the second level conversion module 13.

[0052] Moreover, because the manufacturing cost of transistors is lower, when transistors are used to build the first level conversion module 11 and the second level conversion module 13, the design cost required for the first level conversion module 11 and the second level conversion module 13 can be further reduced.

[0053] Obviously, through the technical solution provided by this embodiment, not only can the cost investment of the serial port expansion circuit be reduced, but also the development efficiency of the serial port expansion can be improved.

[0054] Based on the above embodiment, this embodiment further explains and optimizes the technical solution. As a preferred implementation manner, the first level conversion module 11 is specifically a module that converts RS232 signals into TTL level signals, and the second level conversion module 13 is specifically a module that converts TTL level signals into RS485 signals.

[0055] Since the RS485 signal uses a differential signal data transmission mode, it can effectively suppress the interference of external signals and improve the stability and reliability of the serial port expansion circuit during signal transmission. Moreover, the RS485 signal supports long-distance data transmission, with a maximum distance of over 1200 meters. Therefore, when the serial port expansion circuit needs to be applied in a long-distance signal transmission scenario, the first level conversion module 11 in the serial port expansion circuit can be set as a module that converts the RS232 signal into a TTL level signal, and the second level conversion module 13 can be set as a module that converts the TTL level signal into an RS485 signal.

[0056] In addition, in practical applications, all of the multiple second level conversion modules 13 in the serial port expansion circuit can be set as modules that convert the TTL level signal into an RS232 signal, or all of the multiple second level conversion modules 13 can be set as modules that convert the TTL level signal into an RS485 signal. Alternatively, a part of the multiple second level conversion modules 13 can be set as modules that convert the TTL level signal into an RS232 signal, and another part of the multiple second level conversion modules 13 can be set as modules that convert the TTL level signal into an RS485 signal.

[0057] Please refer to Figure 5 and Figure 6 , Figure 5 and Figure 6 which are respectively the structural diagrams of another serial port expansion circuit provided by the embodiments of the present invention. In the serial port expansion circuit shown in Figure 5 , the multiplexer 12 is set as a double-pole four-throw analog switch chip, and all of the second level conversion modules 13 are set as modules that convert the TTL level signal into an RS485 signal. At this time, 4 RS485 interfaces can be expanded using this serial port expansion circuit. In the serial port expansion circuit shown in Figure 6 , the multiplexer 12 is set as a double-pole four-throw analog switch chip, and two of the second level conversion modules 13 are respectively set as a module that converts the TTL level signal into an RS232 signal and a module that converts the TTL level signal into an RS485 signal. At this time, 2 RS232 interfaces and 2 RS485 interfaces can be expanded using this serial port expansion circuit. Obviously, when the multiple second level conversion modules 13 in the serial port expansion circuit are set in a mixed structure mode of converting the TTL level signal into an RS232 signal module and converting the TTL level signal into an RS485 signal module, not only can the expansion of the RS232 interface on the industrial control board be achieved, but also the expansion of the RS485 interface can be achieved. Thus, the serial port expansion circuit provided by this application can be applied to more industrial control scenarios.

[0058] Obviously, through the technical solution provided in this embodiment, the diversity and flexibility in expanding the RS232 interface on the serial port expansion circuit can be further improved.

[0059] Based on the above embodiment, this embodiment further explains and optimizes the technical solution. As a preferred implementation manner, the above circuit further includes:

[0060] A power supply module that is connected to the multiplexer 12, the first level conversion module 11, and the second level conversion module 13, and is used to supply power to the multiplexer 12, the first level conversion module 11, and the second level conversion module 13.

[0061] In this embodiment, in order to further improve the stability of the serial port expansion circuit during operation, a power supply module for supplying power to the multiplexer 12, the first level conversion module 11, and the second level conversion module 13 can also be added to the serial port expansion circuit, so that the multiplexer 12, the first level conversion module 11, and the second level conversion module 13 have sufficient power sources during operation.

[0062] Please refer to Figure 7 , Figure 7 which is the structural diagram of another serial port expansion circuit provided by the embodiment of the present invention. In the Figure 7 shown serial port expansion circuit, the power supply module 15 is used to supply power to the multiplexer 12, the first level conversion module 11, and the second level conversion module 13. Among them, TX represents signal transmission, RX represents signal reception, the control terminals IN1 and IN2 of the multiplexer 12 are connected to the IO interfaces IO1 and IO2 on the industrial control board 101, the input terminal of the multiplexer 12 is connected to the RS232 interface of the industrial control board 101 through the first level conversion module 11, and a second level conversion module 13 is connected to each output terminal of the multiplexer 12.

[0063] It should be noted that in Figure 7In the serial port expansion circuit shown, the multiplexer 12 in the serial port expansion circuit is set as a double - pole four - throw analog switch chip, and multiple second - level conversion modules 13 are all set as modules for converting TTL - level signals to RS232 signals. In this way, 4 RS232 interfaces can be expanded. Of course, in actual applications, multiple second - level conversion modules 13 in the serial port expansion circuit can also be all set as modules for converting TTL - level signals to RS485 signals, so that 4 RS485 interfaces can be expanded. Or, multiple second - level conversion modules 13 in the serial port expansion circuit can be set in a structural mode that mixes modules for converting TTL - level signals to RS232 signals and modules for converting TTL - level signals to RS485 signals, so as to achieve the purpose of expanding both RS232 interfaces and RS485 interfaces.

[0064] Obviously, through the technical solution provided by this embodiment, the overall stability of the serial port expansion circuit during operation can be further improved.

[0065] Based on the above - mentioned embodiment, this embodiment further explains and optimizes the technical solution. As a preferred implementation manner, the multiplexer 12 is specifically a multi - channel analog switch chip.

[0066] Because the multi - channel analog switch can not only complete the switching of signal channels within nanoseconds, but also has low power consumption, can maintain low on - resistance and off - resistance, and reduce signal distortion and attenuation. Therefore, when the multiplexer 12 is set as a multi - channel analog switch chip, the working performance of the serial port expansion circuit can be improved.

[0067] As a preferred implementation manner, a BBM delay module is provided on the multi - channel analog switch chip.

[0068] In actual applications, a BBM (Break Before Make) delay module can also be provided on the multi - channel analog switch chip. Because the BBM delay module can ensure the mutual isolation between signal switching paths on the multi - channel analog switch chip, avoid signal interference during switching, and avoid crosstalk or distortion phenomena that occur when the transmitted signal is transmitted from one signal output channel to another signal output channel. Therefore, when a BBM delay module is provided on the multi - channel analog switch chip, the stability and reliability of the serial port expansion circuit during operation can be further improved.

[0069] Obviously, through the technical solution provided by this embodiment, not only can the working performance of the serial port expansion circuit be improved, but also the overall reliability of the serial port expansion circuit during operation can be ensured.

[0070] Based on the technical content disclosed in the foregoing embodiments, a detailed description of the above-disclosed content is given herein through an application scenario example. Please refer to Figure 8 , Figure 8 which is a structural diagram of another serial port expansion circuit provided by an embodiment of the present invention.

[0071] In Figure 8 the serial port expansion circuit shown, a first level conversion module 11, a multiplexer 12, a second level conversion module 13, an optocoupler 14, a power supply VCC, and a resistor R are provided. Specifically, the multiplexing switch 12 is set as a double-pole four-throw analog switch chip. The first level conversion module 11 is used to convert the RS232 signal into a TTL level signal, and the second level conversion module 13 is used to convert the TTL level signal into an RS232 signal.

[0072] The control terminal of the multiplexer 12 is connected to the IO interfaces IO1 and IO2 of the industrial control board 101 through the optocoupler 14. The input terminal of the multiplexer 12 is connected to the RS232 interface of the industrial control board 101 through the first level conversion module 11. Each output terminal of the multiplexer 12 is connected to a second level conversion module 13.

[0073] When the industrial control board 101 outputs an RS232 signal through the RS232 interface, the first level conversion module 11 will convert the RS232 signal into a TTL level signal. At the same time, the industrial control board 101 can select a certain output channel in the multiplexer 12 as the output channel of the TTL level signal by logically combining the IO signals output by the two IO interfaces, thereby realizing the expansion function of the RS232 interface on the industrial control board 101. Four RS232 interfaces can be expanded using this serial port expansion circuit.

[0074] It should be noted that after the IO signal output by the industrial control board 101 is driven by the optocoupler 14, it can achieve longer-distance signal transmission and also makes the IO signal have strong anti-interference performance, thereby ensuring the reliability of the signal during transmission. Moreover, this setting method can also make the circuit assembly position relatively free.

[0075] Obviously, when using the Figure 8 circuit shown to expand the RS232 interface on the industrial control board, neither the industrial control board needs to be modified nor the components in the serial port expansion circuit need to be modified, which can reduce the complexity of expanding the RS232 interface on the industrial control board. Moreover, the manufacturing cost of the multiplexer, the first level conversion module, and the second level conversion module is low, thereby significantly reducing the cost investment required for expanding the RS232 interface on the industrial control board.

[0076] It should be noted that in Figure 8 the serial port expansion circuit shown, the second level conversion module 13 is set as a module for converting TTL level signals to RS232 signals, thus expanding 4 RS232 interfaces. Of course, in actual applications, multiple second level conversion modules 13 in the serial port expansion circuit can also be set as modules for converting TTL level signals to RS485 signals, so that 4 RS485 interfaces can be expanded. Or, multiple second level conversion modules 13 in the serial port expansion circuit can also be set in a structural mode that mixes modules for converting TTL level signals to RS232 signals and modules for converting TTL level signals to RS485 signals, so as to achieve the purpose of expanding both RS232 interfaces and RS485 interfaces.

[0077] Correspondingly, an embodiment of the present invention further provides a signal control system, including a serial port expansion circuit as disclosed above.

[0078] The signal control system provided by the embodiment of the present invention has the beneficial effects of the serial port expansion circuit provided above.

[0079] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A serial port expansion circuit, characterized in that: include: A multiplexer, a first level conversion module for converting an RS232 signal into a target digital signal, and a plurality of second level conversion modules for converting the target digital signal into a serial communication signal; Among them, the input end of the multiplexer is connected to the RS232 interface of the industrial control board through the first level conversion module, the control end of the multiplexer is connected to the IO interface of the industrial control board, and each output end of the multiplexer is connected to one of the second level conversion modules.

2. A serial port expansion circuit according to claim 1, characterized in that: Also includes: Optocoupler; Wherein, the control end of the multiplexer is connected to the IO interface of the industrial control board through the optical coupler.

3. A serial port expansion circuit according to claim 1, characterized in that: The first level conversion module is specifically a module for converting the RS232 signal into a TTL level signal, and the second level conversion module is specifically a module for converting the TTL level signal into the RS232 signal.

4. A serial port expansion circuit according to claim 3, characterized in that: The first level conversion module and the second level conversion module are both modules constructed by logic gate circuits.

5. A serial port expansion circuit according to claim 3, characterized in that: The first level conversion module and the second level conversion module are both modules constructed by triodes.

6. A serial port expansion circuit according to claim 1, characterized in that: The first level conversion module is specifically a module for converting the RS232 signal into a TTL level signal, and the second level conversion module is specifically a module for converting the TTL level signal into an RS485 signal.

7. The serial port expansion circuit according to claim 1, characterized in that: Also includes: A power supply module connected to the multiplexer, the first level conversion module and the second level conversion module, and used to supply power to the multiplexer, the first level conversion module and the second level conversion module.

8. A serial port expansion circuit according to any one of claims 1 to 7, characterized in that: The multiplexer is specifically a multi-channel analog switch chip.

9. A serial port expansion circuit according to claim 8, characterized in that: The multi-channel analog switch chip is provided with a BBM delay module.

10. A signal control system, characterized in that: It comprises a serial port expansion circuit as claimed in any one of claims 1 to 9.

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