Bus line switching circuit and elevator control system
By using a bus line switching circuit, stable and reliable communication between handheld devices and the main control system of automated equipment is achieved, which solves the problems of bus communication being susceptible to interference and increased costs, reduces bus resource consumption, and improves ease of operation.
Patent Information
- Application Number
- CN202422608989.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-28
- Publication Date
- 2026-01-13
- Estimated Expiration
- 2034-10-28
AI Technical Summary
In existing technologies, bus communication between handheld devices and the main control system of automated equipment is susceptible to interference when the distance is long, and adding extra bus resources increases costs.
A bus line switching circuit is provided, which realizes the bus communication switching between the main control system and the first and second devices through the bus trunk, first and second bus branches, interface circuit, sampling circuit, control circuit and switching switch circuit, sharing bus resources and reducing bus resource consumption.
It enables stable and reliable communication between handheld devices and the main control system of automated equipment without increasing bus resources, reducing product costs and improving ease of use.
Smart Images
Figure CN223798244U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of hardware control technology, and in particular to a bus switching circuit and an elevator control system. Background Technology
[0002] With the significant improvement in the informatization, technological advancement, and independent innovation capabilities of my country's manufacturing industry, industrial automation equipment (such as frequency converters, CNC machine tools, and industrial robots) plays a crucial role in the transformation of my country's manufacturing industry, the promotion of urbanization, and import and export trade. For the efficient operation and maintenance of industrial automation control equipment, maintenance personnel often need to interact with the main control system through relevant operating interfaces to query information and modify parameters. However, in most scenarios, once parameters are set, they cannot be arbitrarily modified by others. Therefore, when maintaining the equipment, maintenance personnel often insert handheld devices into the interface of the automation equipment to interact with the main control system; after setting the parameters, they unplug the handheld devices and take them away. This method offers advantages such as ease of operation, simple debugging, safety, and high efficiency, significantly reducing the costs of equipment debugging and maintenance management.
[0003] Currently, there are various types of handheld devices, but most products on the market are only suitable for situations where the handheld device and the main control system of the automated equipment are relatively close (generally within 2 meters). Once the distance exceeds two meters or even more than ten meters, the signal is easily affected by external interference, the communication quality will be greatly reduced, and communication may even fail. To solve this problem, a bus communication method is needed between the handheld device and the main control system of the automated equipment to improve the signal anti-interference capability. However, adding a separate bus communication channel requires additional bus resources, which increases the cost of the product. Utility Model Content
[0004] The main purpose of this invention is to provide a bus line switching circuit and controller, which aims to solve the cost problem of stable and reliable communication in the main control system of handheld devices and automated equipment.
[0005] To achieve the above objectives, this application provides the following technical solution:
[0006] A bus line switching circuit, comprising: a bus trunk, a first bus branch, a second bus branch, an interface circuit, a sampling circuit, a control circuit, and a switching circuit, wherein...
[0007] One end of the bus trunk is connected to the switching circuit, and the other end is connected to the main control system; one end of the first bus branch is connected to the switching circuit, and the other end is connected to the first device; one end of the second bus branch is connected to the switching circuit, and the other end is connected to the interface circuit, the interface circuit being used for bus communication connection between the second device and the second bus branch; the switching circuit is used to switch the electrical connection between the first bus branch and the second bus branch and the bus trunk, so as to realize the bus communication switching between the main control system and the first device and the second device;
[0008] The interface circuit includes a power interface and a bus communication interface. The power interface outputs power VCC1 to provide operating power to the second device. The bus communication interface is used to realize the bus communication connection between the second bus branch and the second device.
[0009] The input terminal of the sampling circuit is connected to the interface circuit, and the output terminal of the sampling circuit is connected to the input terminal of the control circuit. The sampling circuit is used to sample the operating current of the second device.
[0010] The output terminal of the control circuit is connected to the control terminal of the switching circuit. The control circuit controls the switching circuit to switch the first device or the second device to communicate with the main control system according to the output signal of the sampling circuit.
[0011] Optionally, the sampling circuit includes a current sensor and an operational amplifier circuit, wherein the output terminal of the current sensor is connected to the input terminal of the operational amplifier circuit; the current sensor is connected in series in the power supply circuit of the second device to obtain the operating current of the second device.
[0012] Optionally, the switching circuit includes a double-pole switch relay K1, which includes a moving contact, a first stationary contact, and a second stationary contact. The moving contact is connected to the main bus line, the first stationary contact is connected to the first bus branch, and the second stationary contact is connected to the second bus branch. Under the control of the control circuit, the moving contact switches between the first stationary contact and the second stationary contact to realize the line switching connection between the first bus branch, the second bus branch, and the main bus line.
[0013] Optionally, the double-pole switch relay K1 further includes a power input terminal 1 and a power output terminal 2. The moving contact includes a first moving contact and a second moving contact. The first stationary contact includes a first stationary contact and a second stationary contact. The second stationary contact includes a third stationary contact and a fourth stationary contact. The bus trunk includes a signal transmitting terminal A+ and a signal receiving terminal A-. The first bus branch 101 includes a first signal transmitting terminal A1+ and a first signal receiving terminal A1-. The second bus branch 102 includes a second signal transmitting terminal A2+ and a second signal receiving terminal A2-. The signal transmitting terminal A+ is connected to the second moving contact. The signal receiving terminal A- is connected to the first moving contact. The first signal transmitting terminal A1+ is connected to the second stationary contact. The first signal receiving terminal A1- is connected to the first stationary contact. The second signal transmitting terminal A2+ is connected to the fourth stationary contact. The second signal receiving terminal A2- is connected to the third stationary contact.
[0014] When the main control system 60 switches to communicate with the first device 70, the first moving contact is connected to the first stationary contact, and the second moving contact is connected to the second stationary contact.
[0015] When the main control system 60 switches to communicate with the second device 80, the first moving contact is connected to the third stationary contact, and the second moving contact is connected to the fourth stationary contact.
[0016] Optionally, the second device can be plugged into the interface circuit, and the second device is a handheld mobile device.
[0017] Optionally, the switching circuit further includes: a power supply VCC2 and a switching unit, wherein the power supply VCC2 is connected to the power input terminal 1, the first end of the switching unit is connected to the power output terminal 2, and the second end of the switching unit is connected to the ground GND2 corresponding to the power supply VCC2.
[0018] Optionally, the control circuit includes a comparator and a reference power supply, wherein the non-inverting input of the comparator is connected to the reference power supply, the inverting input of the comparator is connected to the output of the sampling circuit 30, and the output of the comparator is connected to the control terminal of the switching unit.
[0019] Optionally, the switching unit includes a transistor Q1, the base of which is connected to the output terminal of the comparator, the collector of which is connected to the power output terminal 2, and the emitter of which is connected to ground GND2 corresponding to the power supply VCC2.
[0020] Optionally, the current sensor includes a sampling resistor R1, which is connected in series between the power supply VCC1 and the ground GND2 corresponding to the power supply VCC1, to sample the operating current of the handheld mobile device.
[0021] This utility model also provides an elevator control system, including a main control system, a first device, and a bus line switching circuit as described above.
[0022] This utility model has at least the following technical benefits:
[0023] The bus line switching circuit provided by this utility model has a first device connected to a switching circuit via a first bus branch and a second device connected to the switching circuit via a second bus branch. The control circuit controls the switching circuit to operate based on the sampled operating current of the second device to achieve automatic switching between the two bus branches and the main bus. Compared with existing bus circuits, the first and second devices share a single bus resource, reducing the consumption of bus resources and lowering product costs. Attached Figure Description
[0024] Figure 1 This is a structural block diagram of the bus line switching circuit provided in an embodiment of this application;
[0025] Figure 2 A schematic diagram of the bus line switching circuit provided in the embodiments of this application;
[0026] Figure 3 Another schematic diagram of the bus line switching circuit provided in the embodiments of this application;
[0027] Figure 4 This is a structural block diagram of another elevator control system provided in this embodiment. Detailed Implementation
[0028] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0029] It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit this application.
[0030] In this application, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that an apparatus or system comprising a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such an apparatus or system. Without further limitation, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the apparatus or system that includes that element.
[0031] like Figure 1 , Figure 2 , Figure 3 The diagram illustrates a block diagram and schematic diagram of a bus switching circuit according to an embodiment of this application. The circuit includes: a bus trunk 10, a first bus branch 101, a second bus branch 102, an interface circuit 20, a sampling circuit 30, a control circuit 40, and a switching circuit 50. One end of the bus trunk 10 is connected to the switching circuit 50, and the other end is connected to the main control system 60. One end of the first bus branch 101 is connected to the switching circuit 50, and the other end is connected to a first device 70. One end of the second bus branch 102 is connected to the switching circuit 50, and the other end is connected to the interface circuit 20. The interface circuit 20 is used for bus communication connection between the second device 80 and the second bus branch 102. The switching circuit is used to switch the electrical connection between the first bus branch 101 and the second bus branch 102 and the bus trunk 10, thereby enabling bus communication switching between the main control system 60 and the first device 70 and the second device 80.
[0032] The interface circuit 20 includes a power interface and a bus communication interface. The power interface outputs power VCC1 to provide operating power to the second device 80. The bus communication interface is used to realize the bus communication connection between the second bus branch 102 and the second device 80.
[0033] The input terminal of the sampling circuit 30 is connected to the interface circuit 20, and the output terminal of the sampling circuit 30 is connected to the input terminal of the control circuit 40. The sampling circuit 30 is used to sample the operating current of the second device 80.
[0034] The output terminal of the control circuit 40 is connected to the control terminal of the switching circuit 50. The control circuit 40 controls the switching circuit 50 to switch the first device 70 or the second device 80 to communicate with the main control system 60 according to the output signal of the sampling circuit 30.
[0035] The bus line switching circuit provided in this application embodiment includes a main control system 60 connected to a switching circuit 50 via a bus trunk 10, a first device 70 connected to the switching circuit 50 via a first bus branch 101, and an interface circuit 20 connected to the switching circuit 50 via a second bus branch 102. A second device 80 is pluggably connected to the interface circuit 20. The interface circuit 20 has an interface for bus communication with the second device 80 and a power supply VCC1 to provide operating power to the second device. A sampling circuit 30 samples the current I of the operating power supply circuit. A control circuit 40 outputs high and low levels according to the magnitude of the sampled current I to control the switching circuit 50 to switch. For example, when the second device 80 is inserted into the interface circuit 20, the power supply VCC1 provides operating power to the second device 80, and the current I of the operating power supply circuit is I1. When the second device 80 is unplugged from the interface circuit 20, the power supply VCC1 disconnects from providing operating power to the second device 80, and the current I of the operating power supply circuit is I2. Since I1 is much larger than I2, the control unit 40 can determine whether the second device 80 is connected to the interface circuit 20 based on the value of the current I. If the detected current is I1, it outputs a low level to control the switching circuit 50 to connect the first bus branch 101 and the bus trunk 10. If the detected current is I2, it outputs a high level to control the switching circuit 50 to connect the second bus branch 102 and the bus trunk 10. This realizes that when the second device 80 is inserted into the interface circuit 20, the bus communication connection relationship automatically switches from the connection between the first device 70 and the main control system 60 to the connection between the second device 80 and the main control system 60. When the second device 80 is unplugged from the interface circuit 20, the bus communication connection relationship automatically switches back from the connection between the second device 80 and the main control system 60 to the connection between the first device 70 and the main control system 60.
[0036] In this embodiment, the bus can be RS485 or CAN bus, the first device 70 can be an IoT device, a touch screen, a PLC, or other such device, and the second device 80 can be a handheld device, such as a handheld operator or a teach pendant, etc., without any restrictions.
[0037] In order to realize bus communication between the handheld device and the main control system 60, the existing technology requires an additional independent bus, and the communication control chip needs to be configured with corresponding bus resources, which increases the product cost. The bus line switching circuit provided in this application embodiment, through the above solution, does not require additional bus resources compared with the existing bus circuit, and realizes automatic switching of bus communication between the first device 60, the second device 70 and the main control system 60 in a low cost and reliably.
[0038] Optionally, the sampling circuit 30 includes a current sensor 301 and an operational amplifier circuit, wherein the current sensor 301 can be a high-precision sampling resistor or a Hall sensor, etc., which is not limited here; the output terminal of the current sensor 301 is connected to the input terminal of the operational amplifier circuit; the current sensor 301 is connected in series in the power supply circuit of the second device 80 to obtain the operating current of the second device 80.
[0039] The current sensor 301 is used to convert the sampled operating current signal of the second device 80 into a voltage signal. Since the operating current of the second device is generally not large, an operational amplifier circuit is needed to amplify the converted voltage signal, which helps to improve the control accuracy of the control circuit 40 and can more accurately determine whether the second device 80 is inserted into the interface circuit 20.
[0040] Optionally, the current sensor includes a sampling resistor R1, which is connected in series between the power supply VCC1 and the corresponding ground GND2 to sample the operating current of the handheld mobile device. When the handheld mobile device is plugged into the interface circuit 20, the power supply VCC1 supplies power to the handheld mobile device, generating a current in the VCC1-GND2 loop. When this current passes through the sampling resistor R1, a voltage difference is generated across the resistor R1, and this voltage signal is output to the input of the operational amplifier.
[0041] The current sensor using a sampling resistor has a simple circuit structure and low cost.
[0042] The current sensor 301 samples the operating current of the second device 80, which is the current I in the operating power supply circuit of the second device 80. The current sensor 301 converts the current I into a voltage signal and outputs it to the input terminal of the operational amplifier circuit. The operational amplifier circuit amplifies the voltage signal and outputs it to the input terminal of the control circuit 40.
[0043] The amplification factor of the operational amplifier circuit can be set as needed. The setting of the amplification factor is a standard industry technique and will not be described in detail here. Optionally, the switching circuit 50 includes a double-pole switch relay K1. The double-pole switch relay K1 includes a moving contact, a first stationary contact, and a second stationary contact. The moving contact is connected to the main bus 10, the first stationary contact is connected to the first bus branch 101, and the second stationary contact is connected to the second bus branch 102. Under the control of the control circuit 40, the moving contact switches between the first stationary contact and the second stationary contact to achieve the switching connection between the first bus branch 101, the second bus branch 102, and the main bus 10.
[0044] Under the control of the control circuit 40, the double-pole switch relay K1 can switch the connection between the moving contact and the first stationary contact. The double-pole switch relay K1 includes normally closed contacts. Normally closed contacts refer to contacts where the moving contact and the stationary contact remain connected when the relay control terminal is not under external control. Setting the moving contact and the first contact as normally closed contacts can ensure the reliability of the communication connection between the first device 70 and the main control system 60.
[0045] Optionally, the double-pole switch relay K1 also includes a power input terminal 1, a power output terminal 2, moving contacts including a first moving contact 5 and a second moving contact 6, a first stationary contact including a first stationary contact 3 and a second stationary contact 4, a second stationary contact including a third stationary contact 7 and a fourth stationary contact 8; the bus trunk 10 includes a signal transmitting terminal A+ and a signal receiving terminal A-, the first bus branch 101 includes a first signal transmitting terminal A1+ and a first signal receiving terminal A1-, and the second bus branch 102 includes a second signal transmitting terminal A2+ and a second signal receiving terminal A2. -; Signal transmitting end A+ is connected to the second moving contact 6, signal receiving end A- is connected to the first moving contact 5, first signal transmitting end A1+ is connected to the second stationary contact 4, first signal receiving end A1- is connected to the first stationary contact 3, second signal transmitting end A2+ is connected to the fourth stationary contact 8, and second signal receiving end A2- is connected to the third stationary contact 7; the first moving contact 5 is switched to conduct with the first stationary contact 3 and the third stationary contact 7 respectively, and the second moving contact 6 is switched to conduct with the second stationary contact 4 and the fourth stationary contact 8 respectively.
[0046] The moving contact, first stationary contact, and second stationary contact of the double-pole switch relay K1 each include a pair of contacts. Each pair of contacts contains two contacts, which can ensure that the two contacts of each pair are connected or disconnected at the same time, meeting the timing requirements for bus signal reception and transmission.
[0047] Optionally, the switching circuit 50 further includes: a power supply VCC2 and a switching unit 501. The power supply VCC2 is connected to the power input terminal 1, the first end of the switching unit 501 is connected to the power output terminal 2, and the second end of the switching unit 501 is connected to the ground GND2 corresponding to the power supply VCC2.
[0048] Since the bus communication line includes two differential lines for signal transmission and signal reception, the bus trunk 10, the first bus branch 101, and the second bus branch 102 each include two differential lines. Therefore, the moving contact, first stationary contact, and second stationary contact of the double-pole switch relay K1 each require two contacts to connect to the corresponding bus trunk 10, first bus branch 101, and second bus branch 102. The double-pole switch relay K1 can be selected as a normally closed relay with both the moving contact and the first stationary contact. The switch unit 501 controls the power supply VCC2 to power the double-pole switch relay K1. When the switch unit 501 is turned on, it controls... When power supply VCC2 connects the power supply circuit to double-pole switch relay K1, double-pole switch relay K1 operates, and the moving contact switches from being connected to the first stationary contact to being connected to the second stationary contact. When switch unit 501 is not connected, the power supply circuit of control power supply VCC2 to double-pole switch relay K1 is disconnected. If the moving contact of relay K1 is connected to the first stationary contact at the moment of disconnection, the moving contact does not operate and remains connected to the first stationary contact. If the moving contact of relay K1 is connected to the second stationary contact at the moment of disconnection, the moving contact switches from being connected to the second stationary contact to being connected to the first stationary contact.
[0049] Optionally, the second device 80 is a handheld mobile device. The handheld mobile device is a handheld operator, a teach pendant, etc.
[0050] The handheld device can be plugged into the interface circuit 20 when in use, and unplugged after use so that it can be taken to another device for reuse, which greatly saves the cost of the device.
[0051] Optionally, the control circuit 40 includes a comparator and a reference power supply 401. The non-inverting input of the comparator is connected to the reference power supply 401, the inverting input of the comparator is connected to the output of the sampling circuit 30, and the output of the comparator is connected to the control terminal of the switching unit.
[0052] The comparator compares the output signal of the sampling circuit 30 with the reference power supply 401. If the output signal voltage of the sampling circuit 30 is greater than the voltage of the reference power supply 401, the control circuit outputs a high level to turn on the switch unit 501. If the output signal voltage of the sampling circuit 30 is less than the voltage of the reference power supply 401, the control circuit outputs a low level to turn off the switch unit 501. The reference power supply 401 can be generated by voltage division through resistors from power supply VCC3, or by voltage regulation through power supply VCC3. The voltage value of the reference power supply 401 can be set according to the output voltage value of the sampling unit 30. It is necessary to ensure that the output voltage value of the sampling unit 30 is greater than the voltage of the reference power supply 401 when the second device 80 is inserted into the interface circuit. Among them, power supplies VCC1, VCC2, and VCC3 can be the same power supply or three different independent power supplies.
[0053] Optionally, the switching unit includes a transistor Q1, with the base of transistor Q1 connected to the output terminal of the comparator, the collector connected to the power output terminal 2, and the emitter connected to ground GND2 corresponding to the power supply VCC2.
[0054] When the comparator outputs a high level, the transistor is turned on, and the power supply circuit of the control power supply VCC2 to the double-pole switch relay K1 is turned on; when the comparator outputs a low level, the transistor is turned off, and the power supply circuit of the control power supply VCC2 to the double-pole switch relay K1 is turned off.
[0055] The switching unit uses transistors, which have the advantages of simple circuitry and fast response speed.
[0056] In order to achieve bus communication between the handheld device and the main control system 60, the existing technology requires an additional bus resource. The bus line switching circuit provided in this application embodiment achieves stable and reliable communication between the handheld device and the main control system of the automation equipment without adding additional bus resources, compared with the existing bus circuit. This reduces system costs and improves ease of use in field operation.
[0057] This application embodiment also provides an elevator control system 100, such as... Figure 4 As shown, it includes a main control system 60, a first device 70, and a bus line switching circuit as described above; the second device 80 is pluggably connected to the elevator control system 100.
[0058] In some embodiments, the main control system 60 may be the control unit of the elevator drive, the first device 70 may be an Internet of Things (IoT) device, and the second device 80 may be a handheld operator. Under normal operating conditions, the control unit of the elevator drive and the IoT device communicate via a bus. When the elevator control system 100 requires maintenance, maintenance personnel may need to set some parameters for the elevator control system 100 via a handheld operator. At this time, the handheld operator and the main control system 60 need to interact, and the interaction data is transmitted via bus communication. When the handheld operator is inserted into the interface circuit 20, the control circuit 40 controls the switching circuit 50 to switch the bus communication between the IoT device and the control unit of the elevator drive to communication between the handheld operator and the control unit of the elevator drive. This realizes that the handheld operator and the IoT device share a single bus communication line, reducing bus resource consumption and lowering product costs.
[0059] It should be noted that the specific structure of the elevator control system 100 refers to the above embodiments. Since the elevator control system adopts all the technical solutions of all the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be described in detail here.
[0060] The above are only some embodiments of this application and do not limit the patent scope of this application. All equivalent structural transformations made under the technical concept of this application and using the contents of the specification and drawings of this application, or direct / indirect applications in other related technical fields, are included in the patent protection scope of this application.
Claims
1. A bus line switching circuit, characterized in that, The bus line switching circuit includes: a bus trunk (10), a first bus branch (101), a second bus branch (102), an interface circuit (20), a sampling circuit (30), a control circuit (40), and a switching circuit (50), wherein, One end of the bus trunk (10) is connected to the switching circuit (50), and the other end is connected to the main control system (60); one end of the first bus branch (101) is connected to the switching circuit (50), and the other end is connected to the first device (70); one end of the second bus branch (102) is connected to the switching circuit (50), and the other end is connected to the interface circuit (20), the interface circuit (20) is used for bus communication connection between the second device (80) and the second bus branch (102); the switching circuit is used to switch the electrical connection between the first bus branch (101) and the second bus branch (102) and the bus trunk (10), so as to realize the bus communication switching between the main control system (60) and the first device (70) and the second device (80); The interface circuit (20) includes a power interface and a bus communication interface. The power interface outputs power VCC1 to provide working power to the second device (80). The bus communication interface is used to realize the bus communication connection between the second bus branch (102) and the second device (80). The input terminal of the sampling circuit (30) is connected to the interface circuit (20), and the output terminal of the sampling circuit (30) is connected to the input terminal of the control circuit (40). The sampling circuit (30) is used to sample the operating current of the second device (80). The output terminal of the control circuit (40) is connected to the control terminal of the switching circuit (50). The control circuit (40) controls the switching circuit (50) to switch the first device (70) or the second device (80) to communicate with the main control system (60) according to the output signal of the sampling circuit (30).
2. The bus line switching circuit according to claim 1, characterized in that, The sampling circuit (30) includes a current sensor and an operational amplifier circuit. The output terminal of the current sensor is connected to the input terminal of the operational amplifier circuit. The current sensor is connected in series in the power supply circuit of the second device (80) to obtain the operating current of the second device (80).
3. The bus line switching circuit according to claim 1, characterized in that, The switching circuit (50) includes a double-pole switch relay K1, which includes a moving contact, a first stationary contact, and a second stationary contact. The moving contact is connected to the main bus line (10), the first stationary contact is connected to the first bus branch (101), and the second stationary contact is connected to the second bus branch (102). Under the control of the control circuit (40), the moving contact switches between the first stationary contact and the second stationary contact to realize the line switching connection between the first bus branch (101), the second bus branch (102), and the main bus line (10).
4. The bus line switching circuit according to claim 3, characterized in that, The double-pole switch relay K1 also includes a power input terminal (1) and a power output terminal (2). The moving contact includes a first moving contact (5) and a second moving contact (6). The first stationary contact includes a first stationary contact (3) and a second stationary contact (4). The second stationary contact includes a third stationary contact (7) and a fourth stationary contact (8). The bus trunk (10) includes a signal transmitting terminal A+ and a signal receiving terminal A-. The first bus branch (101) includes a first signal transmitting terminal A1+ and a first signal receiving terminal A1-. The second bus trunk (101) includes a second signal transmitting terminal A1+ and a second signal receiving terminal A1-. The line branch (102) includes a second signal transmitting end A2+ and a second signal receiving end A2-; the signal transmitting end A+ is connected to the second moving contact (6), the signal receiving end A- is connected to the first moving contact (5), the first signal transmitting end A1+ is connected to the second stationary contact (4), the first signal receiving end A1- is connected to the first stationary contact (3), the second signal transmitting end A2+ is connected to the fourth stationary contact (8), and the second signal receiving end A2- is connected to the third stationary contact (7); When the main control system (60) switches to communicate with the first device (70), the first moving contact (5) is connected to the first stationary contact (3), and the second moving contact (6) is connected to the second stationary contact (4); When the main control system (60) switches to communicate with the second device (80), the first moving contact (5) is connected to the third stationary contact (7), and the second moving contact (6) is connected to the fourth stationary contact (8).
5. The bus line switching circuit according to claim 2, characterized in that, The second device (80) is pluggable to the interface circuit (20), and the second device (80) is a handheld mobile device.
6. The bus line switching circuit according to claim 4, characterized in that, The switching circuit (50) further includes: power supply VCC2 and a switching unit. The power supply VCC2 is connected to the power input terminal (1), the first end of the switching unit is connected to the power output terminal (2), and the second end of the switching unit is connected to the ground GND2 corresponding to the power supply VCC2.
7. The bus line switching circuit according to claim 6, characterized in that, The control circuit (40) includes a comparator and a reference power supply. The non-inverting input of the comparator is connected to the reference power supply, the inverting input of the comparator is connected to the output of the sampling circuit (30), and the output of the comparator is connected to the control terminal of the switching unit.
8. The bus line switching circuit according to claim 7, characterized in that, The switching unit includes a transistor Q1, the base of which is connected to the output of the comparator, the collector of which is connected to the power output (2), and the emitter of which is connected to ground GND2 corresponding to the power supply VCC2.
9. The bus line switching circuit according to claim 5, characterized in that, The current sensor includes a sampling resistor R1, which is connected in series between the power supply VCC1 and the ground GND2 corresponding to the power supply VCC1, to sample the operating current of the handheld mobile device.
10. An elevator control system, characterized in that, It includes a main control system (60), a first device (70), and a bus line switching circuit as described in any one of claims 1-9.