RS485 bus equipment

Abstract

The utility model provides RS485 bus equipment, which comprises an isolation RS485 driver electrically connected with an RS485 sensor, the isolation RS485 driver is electrically connected with a microcontroller and an isolation power supply, the isolation power supply is electrically connected with the RS485 sensor through an isolation current and voltage sampling circuit, an electronic switch is arranged between the isolation current and voltage sampling circuit and the RS485 sensor, and the microcontroller is electrically connected with the isolation power supply. The microcontroller is electrically connected with the isolation current and voltage sampling circuit and the electronic switch so as to control on-off of the electronic switch according to the current value and / or the voltage value. By arranging the isolation power supply, the situation that the reliability of equipment is reduced due to the fact that a power line is additionally arranged to be collinear with the RS485 bus is avoided, and the running stability of the equipment is improved; the isolation current and voltage sampling circuit is arranged to monitor the current value and / or the voltage value, the electronic switch is controlled to switch off or switch on the power supply circuit, it is ensured that when power supply is abnormal, power supply is cut off in time, and the reliability of the RS485 bus equipment is further improved.

Description

Technical Field

[0001] The utility model relates to the technical field of engineering measurement, in particular to an RS485 bus device. Background Art

[0002] At present, RS485 sensors have been widely used in the field of structural safety monitoring. Due to the characteristics of the RS485 bus, bus reliability plays a vital role in the stability of the entire RS485 system. Therefore, RS485 bus equipment has very high requirements on the drive interface of each RS485 sensor and the bus topology.

[0003] In monitoring scenarios, RS485 sensors all require power, but existing RS485 bus devices do not have a power supply function. Therefore, it is necessary to provide RS485 sensors with additional power cables that run along the RS485 bus. The presence of power cables will directly affect the reliability of RS485 bus devices, thereby reducing their working stability. Utility Model Content

[0004] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide an RS485 bus device, which aims to solve the technical problem that in the existing technology, in order to meet the power supply needs of RS485 sensors, an additional power line is provided for the RS485 sensors to be routed together with the RS485 bus. The existence of the power line will directly affect the reliability of the RS485 bus device, thereby reducing its working stability.

[0005] In order to achieve the above purpose, the present invention is implemented through the following technical solutions:

[0006] An RS485 bus device includes an isolated RS485 driver electrically connected to an RS485 sensor, the isolated RS485 driver electrically connected to a microcontroller and an isolated power supply, the isolated power supply electrically connected to the RS485 sensor via an isolated current and voltage sampling circuit to provide an operating power supply to the RS485 sensor, the isolated current and voltage sampling circuit being used to monitor the current value and / or voltage value of the operating power supply, an electronic switch being provided between the isolated current and voltage sampling circuit and the RS485 sensor, and the microcontroller electrically connected to the isolated current and voltage sampling circuit and the electronic switch to control the on and off of the electronic switch according to the current value and / or the voltage value.

[0007] Compared with the prior art, the beneficial effects of the present invention are as follows: by arranging the isolated power supply in the RS485 bus device and powering the RS485 sensor through the isolated power supply, the function of the RS485 bus device directly powering the RS485 sensor is realized, avoiding the situation where an additional power line is set for the RS485 sensor and the device reliability is reduced due to the co-line with the RS485 bus, thereby improving the stability of the device operation; by arranging the isolated current and voltage sampling circuit, the microcontroller can control the electronic switch to cut off or turn on the circuit that supplies power to the RS485 sensor according to the monitored current value and / or voltage value, ensuring that the power supply is cut off in time when an abnormality occurs in the power supply, thereby further improving the reliability of the RS485 bus device.

[0008] Furthermore, the RS485 sensor includes a plurality of sub-sensors, the electronic switch includes a plurality of sub-switches, and the isolated RS485 driver includes a plurality of sub-drivers, and the number of the sub-sensors, the sub-switches, and the sub-drivers is the same.

[0009] Furthermore, the RS485 bus device also includes a fault judgment circuit, one end of the fault judgment circuit is electrically connected between the RS485 sensor and the isolated RS485 driver, the other end of the fault judgment circuit is electrically connected to the isolated power supply, and the fault judgment circuit is electrically connected to the microcontroller to determine whether the RS485 bus device is open or short-circuited.

[0010] Furthermore, the RS485 bus device further includes a wireless communication module, and the microcontroller is communicatively connected with the remote device via the wireless communication module.

[0011] Furthermore, the RS485 bus device further includes a data storage device, and the microcontroller is electrically connected to the data storage device.

[0012] Furthermore, the isolated current and voltage sampling circuit includes a current sampling resistor R81, which is electrically connected to a fully differential isolation amplifier U18, and the fully differential isolation amplifier U18 is electrically connected to the analog-to-digital converter pin of the microcontroller through an instrumentation amplifier U19.

[0013] Furthermore, the isolated current and voltage sampling circuit further includes a voltage-dividing resistor, which is electrically connected to the isolation voltage amplifier U20, and the isolation voltage amplifier U20 is electrically connected to the analog-to-digital converter pin of the microcontroller through the instrumentation amplifier U21.

[0014] Furthermore, the voltage divider resistor includes a resistor R84 and a resistor R85 connected in series.

[0015] Furthermore, the RS485 sensor and the isolated RS485 driver are electrically connected via the A signal line and the B signal line, the fault judgment circuit includes an optocoupler relay U14, the microcontroller is electrically connected to the TA pin and the TB pin of the optocoupler relay U14 respectively, the isolated power supply is connected to the optocoupler relay U14 and the A signal line via a resistor R66, and the isolated power supply is connected to the optocoupler relay U14 and the B signal line via a resistor R68.

[0016] Furthermore, the fault judgment circuit further includes an optocoupler relay U12, and the microcontroller is electrically connected to the Rpd pin of the optocoupler relay U12 to connect the pull-down resistor R60 to the B signal line through the optocoupler relay U12. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a structural block diagram of the RS485 bus device in the embodiment of the present utility model;

[0018] Figure 2 This is a circuit diagram of an isolated current and voltage sampling circuit in an RS485 bus device in an embodiment of the present utility model;

[0019] Figure 3 A circuit diagram of a fault judgment circuit in an RS485 bus device in an embodiment of the present utility model;

[0020] Description of main component symbols:

[0021] 1. Isolated RS485 driver; 2. Fault judgment circuit; 3. Electronic switch; 4. Microcontroller; 5. Isolated current and voltage sampling circuit; 6. Wireless communication module; 7. Data storage; 8. Isolated power supply.

[0022] The following specific embodiments will further illustrate the present invention in conjunction with the above-mentioned drawings. DETAILED DESCRIPTION

[0023] To facilitate understanding of the present invention, a more comprehensive description of the present invention will be provided below with reference to the accompanying drawings. The drawings illustrate several embodiments of the present invention. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the present invention.

[0024] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be an intermediate element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of this invention are intended only to describe specific embodiments and are not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0026] See also Figures 1 to 3 The RS485 bus device in the embodiment of the present invention includes an isolated RS485 driver 1 electrically connected to the RS485 sensor. The isolated RS485 driver 1 adopts a fully isolated driver, which simultaneously isolates the RS485 differential signal line and the external power supply of the RS485 driver. The grounding of all devices is based on the RS485 bus device side as the reference point. This can prevent the RS485 driver from being damaged due to the ground potential difference between the ground system on the RS485 sensor side and the ground system of the RS485 bus device exceeding the common-mode voltage range of the RS485 driver. It can also prevent the common-mode current introduced by ground loop current from interfering with the RS485 bus. At the same time, the fully isolated driver can also effectively protect the internal circuit of the RS485 bus device from damage. For example, when the RS485 bus encounters transient high-voltage signals such as surges and lightning, the fully isolated driver can effectively isolate the impact of external pulse energy on the internal circuit.

[0027] The isolated RS485 driver 1 is electrically connected to the microcontroller 4 and the isolated power supply 8. The isolated power supply 8 is electrically connected to the RS485 sensor via the isolated current and voltage sampling circuit 5 to provide working power to the RS485 sensor. Since the entire RS485 cloud intelligent acquisition module is fully isolated from the outside, in addition to the isolated RS485 driver 1, an isolated power supply method is also required. This can effectively avoid the impact of common-mode noise generated by ground loops on the RS485 signal and possible damage to the interface caused by external transient high voltage. The isolated current and voltage sampling circuit 5 is used to monitor the current value and / or voltage value of the working power supply. An electronic switch 3 is provided between the isolated current and voltage sampling circuit 5 and the RS485 sensor. It can be understood that the RS485 sensor includes a plurality of sub-sensors, the electronic switch 3 includes a plurality of sub-switches, and the isolated RS485 driver 1 includes a plurality of sub-drivers. The number of sub-sensors, sub-switches, and sub-drivers is the same, that is, each RS485 sensor has a separate power supply line.

[0028] The microcontroller 4 is electrically connected to the isolated current and voltage sampling circuit 5 and the electronic switch 3 to control the on and off of the electronic switch 3 according to the current value and / or the voltage value. By providing the isolated power supply 8 in the RS485 bus device and powering the RS485 sensor through the isolated power supply 8, the RS485 bus device is able to directly power the RS485 sensor, thus avoiding the need to provide an additional power line for the RS485 sensor, which would otherwise be co-wired with the RS485 bus and thus reduce the reliability of the device, thereby improving the stability of the device operation. By providing the isolated current and voltage sampling circuit 5, the microcontroller 4 can control the electronic switch 3 to cut off or turn on the circuit that powers the RS485 sensor according to the monitored current value and / or voltage value, ensuring that the power supply is promptly cut off when an abnormality occurs in the power supply, further improving the reliability of the RS485 bus device.

[0029] Specifically, the isolated current and voltage sampling circuit 5 includes a current sampling resistor R81, which is used to collect the current value of the RS485 sensor power supply. The current sampling resistor R81 is electrically connected to the fully differential isolation amplifier U18, which is used to isolate the current of the RS485 sensor power supply from the subsequent measurement signal chain. The fully differential isolation amplifier U18 is electrically connected to the analog-to-digital converter pin of the microcontroller 4 through the instrumentation amplifier U19. The instrumentation amplifier U19 is used to convert the measured differential signal into a single-ended signal, set a suitable gain, amplify the current signal, and transmit it to the microcontroller 4; the isolated current and voltage sampling circuit 5 also includes a voltage divider resistor, which is used to sample the voltage value of the RS485 sensor power supply. The voltage divider resistor includes a resistor R84 and a resistor R85 connected in series. The voltage divider resistor is electrically connected to the isolation voltage amplifier U20, and the isolation voltage amplifier U20 is electrically connected to the analog-to-digital converter pin of the microcontroller 4 through the instrumentation amplifier U21. It is understandable that the current sampling resistor R81 and the voltage divider resistor are both provided on the power supply line between the isolated power supply 8 and the RS485 sensor. The microcontroller 4 monitors the acquired current value and / or voltage value. When an abnormality occurs in the RS485 sensor itself, it is generally manifested in the current value and voltage value, such as a sudden increase or decrease in current, a decrease in voltage, etc. At the same time, when an abnormality occurs in the power supply circuit of the RS485 sensor, such as when the voltage is zero, it is generally a short circuit, and when the current is zero, it is generally an open circuit.

[0030] The RS485 bus device also includes a fault judgment circuit 2, one end of which is electrically connected between the RS485 sensor and the isolated RS485 driver 1, and the other end of the fault judgment circuit 2 is electrically connected to the isolated power supply 8, and the fault judgment circuit 2 is electrically connected to the microcontroller 4 to determine whether the RS485 bus device is open or short-circuited. Specifically, the RS485 sensor and the isolated RS485 driver 1 are electrically connected to the A signal line and the B signal line, the fault judgment circuit 2 includes an optocoupler relay U14, the microcontroller 4 is electrically connected to the TA pin and the TB pin of the optocoupler relay U14 respectively, the isolated power supply 8 is connected to the optocoupler relay U14 and the A signal line through a resistor R66, and the isolated power supply 8 is connected to the optocoupler relay U14 and the B signal line through a resistor R68. When the RS485 bus is in a static state, that is, all devices on the bus are in a receiving state, at this time, the two signal lines A and B respectively have an equivalent common-mode resistance Rcm to the ground. The resistance value is related to the input resistance and quantity of the isolated RS485 driver 1. On a general bus, the equivalent Rcm ≥ 375 ohms (in accordance with the RS485 physical layer protocol specification requirements). When the RS485 bus device is open-circuited, the equivalent input resistance RIN of the isolated RS485 driver 1 is disconnected from the bus, leaving only the internal equivalent resistance RIN of the isolated RS485 driver 1 on the RS485 bus device side. By temporarily connecting the test power supply to the A signal line or the B signal line in a constant voltage or constant current manner, the open circuit state of the bus can be determined; when the RS485 bus device is short-circuited, the test power supply is loaded between the A signal line or the B signal line in a constant voltage or constant current manner, and the voltage value between the A signal line or the B signal line is measured to determine whether the bus is short-circuited.

[0031] When it is determined that the bus is open, the microcontroller 4 enables the TA pin and TB pin of the optocoupler relay U14 respectively, connects the isolated power supply 8 and the resistor R66, and the isolated power supply 8 and the resistor R68 to the A signal line and the B signal line respectively, and determines the on / off status of the A signal line and the B signal line respectively. For example, when testing whether the A signal line is open, the isolated power supply 8 and the resistor R66, the equivalent input resistor RIN1 inside the isolated RS485 driver 1, and the equivalent input resistor RIN2 on the RS485 sensor side form a loop, wherein RIN1 and RIN2 are in parallel. When the A signal line is open, RIN2 = 0 ohm. When the A signal line is not open, RIN2 is a specific value, approximately in the thousands of ohms level (an integer multiple of 12KΩ). The values ​​of the isolated power supply 8, the resistor R66, and RIN1 are known conditions. By measuring the voltage value of the resistance divider point VA, it can be determined whether the signal line A is open. The same is true for the B signal line, which will not be repeated here. In this embodiment, the fault judgment circuit 2 also includes an optocoupler relay U15, which is electrically connected to the optocoupler relay U14. The optocoupler relay T15 functions as an analog switch to switch the measurement of the VA and VB point voltages, with the aim of reducing the number of subsequent measurement signal chains to simplify circuit design.

[0032] Furthermore, the fault judgment circuit 2 also includes an optocoupler relay U12, and the microcontroller 4 is electrically connected to the Rpd pin of the optocoupler relay U12 to connect the pull-down resistor R60 to the B signal line through the optocoupler relay U12. When it is determined that the bus is short-circuited, the microcontroller 4 first enables the Rpd pin of the optocoupler relay U12 to connect the pull-down resistor R60 to the B signal line. Then, the microcontroller 4 enables the TA pin and TB pin of the optocoupler relay U14 respectively, and measures the voltages at the VA and VB points respectively. If VA=VB, it indicates that the RS485 bus is short-circuited. If VA≠VB, it indicates that the RS485 bus is not short-circuited. By setting up the fault judgment circuit 2, it can cooperate with the isolated current and voltage sampling circuit 5 to achieve comprehensive monitoring of the RS485 bus equipment and circuits, that is, real-time monitoring of the status of the RS485 bus and the RS485 sensor power supply, so as to actively adjust the power supply strategy according to the monitoring results, and be able to promptly locate the fault line and the cause of the fault, further improving the reliability of the RS485 bus equipment. The optocoupler relay U15 is electrically connected to the isolation voltage amplifier U16, and the isolation voltage amplifier U16 is used to isolate the bus state voltage from the subsequent measurement signal chain. The isolation voltage amplifier U16 is electrically connected to the instrumentation amplifier U17, and the instrumentation amplifier U17 is electrically connected to the microcontroller 4 to convert the measured differential signal into a single-ended signal and output it to the microcontroller 4.

[0033] In this embodiment, the RS485 bus device further includes a wireless communication module 6 and a data storage device 7. The microcontroller 4 is connected to the remote device via the wireless communication module 6, and the microcontroller 4 is electrically connected to the data storage device 7. By providing the wireless communication module 6, the monitoring results can be uploaded to the remote device in real time, realizing remote monitoring, configuration, and upgrade functions. By providing the data storage device 7, the sensor data exchanged on the RS485 bus device can be backed up to ensure that the data is not lost due to unexpected situations during operation.

[0034] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0035] The above-described embodiments merely represent several implementation methods of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. An RS485 bus device, characterized in that: The invention comprises an isolated RS485 driver electrically connected to an RS485 sensor, the isolated RS485 driver electrically connected to a microcontroller and an isolated power supply, the isolated power supply electrically connected to the RS485 sensor via an isolated current and voltage sampling circuit to provide working power to the RS485 sensor, the isolated current and voltage sampling circuit being used to monitor the current value and / or voltage value of the working power supply, an electronic switch being provided between the isolated current and voltage sampling circuit and the RS485 sensor, the microcontroller electrically connected to the isolated current and voltage sampling circuit and the electronic switch to control the on and off of the electronic switch according to the current value and / or the voltage value.

2. RS485 bus equipment according to claim 1, characterized in that, The RS485 sensor includes a plurality of sub-sensors, the electronic switch includes a plurality of sub-switches, and the isolated RS485 driver includes a plurality of sub-drivers. The number of the sub-sensors, the sub-switches, and the sub-drivers is the same.

3. RS485 bus equipment according to claim 1, characterized in that, The RS485 bus device also includes a fault judgment circuit, one end of which is electrically connected between the RS485 sensor and the isolated RS485 driver, the other end of which is electrically connected to the isolated power supply, and the fault judgment circuit is electrically connected to the microcontroller to determine whether the RS485 bus device is open or short-circuited.

4. RS485 bus equipment according to claim 1, characterized in that, The RS485 bus device further includes a wireless communication module, and the microcontroller is connected to the remote device through the wireless communication module.

5. RS485 bus equipment according to claim 1, characterized in that, The RS485 bus device further comprises a data storage device, and the microcontroller is electrically connected to the data storage device.

6. RS485 bus equipment according to claim 1, characterized in that, The isolated current and voltage sampling circuit includes a current sampling resistor R81, which is electrically connected to a fully differential isolation amplifier U18. The fully differential isolation amplifier U18 is electrically connected to the analog-to-digital converter pin of the microcontroller through an instrumentation amplifier U19.

7. RS485 bus equipment according to claim 6, characterized in that, The isolated current and voltage sampling circuit further includes a voltage dividing resistor, which is electrically connected to the isolation voltage amplifier U20, and the isolation voltage amplifier U20 is electrically connected to the analog-to-digital converter pin of the microcontroller through an instrumentation amplifier U21.

8. RS485 bus equipment according to claim 7, characterized in that, The voltage divider resistors include a resistor R84 and a resistor R85 connected in series.

9. RS485 bus equipment according to claim 3, characterized in that, The RS485 sensor and the isolated RS485 driver are electrically connected to the A signal line and the B signal line. The fault judgment circuit includes an optocoupler relay U14. The microcontroller is electrically connected to the TA pin and TB pin of the optocoupler relay U14 respectively. The isolated power supply is connected to the optocoupler relay U14 and the A signal line through a resistor R66, and the isolated power supply is connected to the optocoupler relay U14 and the B signal line through a resistor R68.

10. RS485 bus equipment according to claim 9, characterized in that, The fault judgment circuit further includes an optocoupler relay U12 , and the microcontroller is electrically connected to the Rpd pin of the optocoupler relay U12 so as to connect the pull-down resistor R60 to the B signal line through the optocoupler relay U12 .

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