Wired operable display system of instrument

Abstract

The invention discloses a wired operable display system of an instrument, and belongs to the technical field of wired data acquisition and transmission. The system comprises a power supply used for supplying power to the system; the instrument end is used for measuring various parameters of an instrument, converting the parameters into I2C bus signals, buffering and driving the I2C bus signals and then sending the I2C bus signals to the display end; the shielding wire is used as a transmission wire of an I2C bus signal and a power supply between the instrument end and the display end; and the display end is used for receiving the I2C bus signal, converting the I2C bus signal into a digital signal and displaying the digital signal through a display screen. The system has higher use convenience and reliability.

Description

Technical Field

[0001] The invention relates to the technical field of wired data acquisition and transmission, and in particular to a wired operable display system for instruments and meters. Background Art

[0002] In modern process industries, many installed instruments are not equipped with digital displays, or are equipped with display modules but are not conducive to personnel observation (for example, instruments are installed on the top of tanks more than ten meters high or in high-temperature dangerous areas, etc.). In this case, the data collected by the measuring instruments will be transmitted to the background control system, and the staff on site cannot conveniently and timely understand the situation of the materials in the tank and the data collected by the measuring instruments. At present, there are two types of external display modules for mainstream instruments: The first type is directly connected to the bus. This display module is also called a tank-side meter, which displays by collecting bus data. This display module consumes very little power and is low in cost. The disadvantage is that the data display of the tank-side meter can only read specific signals and does not support other protocol forms. For complex signals, multiple tank-side meters may be required for collection and display, which is less convenient to use.

[0003] The second type is to directly make the external display module into a relatively independent wireless instrument, and use wireless technology to complete the signal reception and transmission. This display module is very portable and has a long transmission distance, and can remotely control instruments. The disadvantage is that the signal is greatly affected by the environment and has poor reliability. Summary of the invention

[0004] The purpose of the present invention is to solve the problems existing in the above-mentioned prior art and to provide a wired operable display system for instruments and meters, which has higher convenience of use and reliability.

[0005] The objective of the present invention is achieved through the following technical solutions: A wired operable display system for an instrument, comprising: A power supply, used to supply power to the system; The instrument side is used to measure various parameters of the instrument and convert them into I2C bus signals. After buffering and driving, they are sent to the The display end sends; Shielded wire, used as the transmission wire for I2C bus signal and power supply between the instrument end and the display end; The display end is used to receive the I2C bus signal, convert it into a digital signal, and then display it on the display screen.

[0006] Preferably, the instrument terminal comprises: A power management module, used for converting the input power into power available to each module, and outputting a 4-20mA current signal under the control of the first microprocessor module; Sensor module, used to measure various parameters of the instrument; The first microprocessor module is used to convert the analog signal measured by the sensor module into a digital signal, control the power management module to output a 4-20mA current signal according to the digital signal, and convert the 4-20mA current signal into an I2C bus signal; and transmit the digital signal to the first signal generating module; A first signal generating module is used to modulate the digital signal transmitted from the first microprocessor module and couple it to the 4-20mA current signal output by the power management module; The first transceiver module is used to buffer and drive the I2C bus signal of the first microprocessor module and then send it to the display end.

[0007] Preferably, the first signal generating module is further used to decouple the analog signal transmitted on the I2C bus from the power management module, and transmit the analog signal to the first microprocessor module after demodulating it.

[0008] Preferably, the first transceiver module is further used to receive an I2C bus signal from the display end.

[0009] Preferably, the display terminal comprises: A second transceiver module is used to receive the I2C bus signal from the instrument end and transmit it to the second microprocessor module; The second microprocessor module is used to convert the I2C signal from the second transceiver module into a digital signal and transmit it to the display screen module; The display screen module is used for processing the digital signal from the second microprocessor module and then displaying it.

[0010] Preferably, the display terminal comprises: The switch module is used to receive the switch signal input by the user and transmit it to the second microprocessor module; the second microprocessor module is also used to convert the switch signal into an I2C bus signal and transmit it to the second transceiver module; the second transceiver module is also used to buffer and drive the I2C bus signal from the second microprocessor module and send it to the instrument end.

[0011] Preferably, the display terminal comprises: The boost switch power supply module is used to boost the power supply from the instrument end to the voltage required by the display end.

[0012] Preferably, a relay transceiver is included, the instrument end and the display end are both provided with a transceiver, and the relay transceiver is connected to the two transceivers via the shielded wire.

[0013] Preferably, an I2C bus and a control signal line are provided between the instrument end and its transceiver, and between the display end and its transceiver, and the control signal line is used to control the transceiver state.

[0014] Preferably, an APL bus is used for signal transmission between the instrument end and the display end.

[0015] The advantages of the present invention are: 1. Transmitting signals through the I2C bus instead of the power bus can meet the transmission requirements of composite signals and improve the convenience of use; at the same time, the effective transmission distance can reach more than 30 meters, which can be further extended after the relay transceiver, and the reliability is higher; 2. High versatility, applicable to various existing transmitter instruments; 3. The signal is driven by the transceiver, which can strike a balance between driving capability and power consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A configuration block diagram of a wired operable display system for an instrument provided in Example 1 of this specification; Figure 2 A transceiver configuration block diagram provided in Embodiment 2 of this specification; Figure 3 A configuration block diagram of a wired operable display system for another instrument provided in Example 3 of this specification. DETAILED DESCRIPTION

[0017] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0018] Example 1 like Figure 1 As shown, this embodiment provides a wired operable display system for an instrument, including: A power supply, used to supply power to the system; The instrument side is used to measure various parameters of the instrument and convert them into I2C bus signals. After buffering and driving, they are sent to the The display end sends; Shielded wire, used as the transmission wire for I2C bus signal and power supply between the instrument end and the display end; The display end is used to receive the I2C bus signal, convert it into a digital signal, and then display it on the display screen.

[0019] This embodiment transmits signals through the I2C bus instead of the power bus, which can meet the transmission requirements of composite signals and improve the convenience of use; at the same time, the effective transmission distance can reach more than 30 meters, and the reliability is higher. The following is a detailed introduction to each part of the system.

[0020] The power supply can be an independent external power supply or the power cord of the upper computer and the lower computer to provide 24V DC power supply.

[0021] The instrument side includes: A power management module, used for converting the input 24V power supply into a 3.3V power supply available to each module, and outputting a 4-20mA current signal under the control of the first microprocessor module; The sensor module may include a plurality of sensors disposed inside or outside the instrument, which are controlled by the first microprocessor module and are used to measure various physical quantities such as temperature, pressure, and level, and convert them into analog signals and transmit them to the first microprocessor module; The first microprocessor module is used to convert the analog signal measured by the sensor module into a digital signal, on the one hand, control the power management module to output a 4-20mA current signal according to the digital signal, and convert the 4-20mA current signal into an I2C bus signal; on the other hand, transmit the digital signal to the first signal generation module; The first signal generating module is generally used to transmit HART signals. On the one hand, it decouples the analog signal transmitted from the I2C bus from the power management module, demodulates the analog signal and transmits it to the first microprocessor module; on the other hand, it modulates the digital signal transmitted from the first microprocessor module and couples it to the 4-20mA current signal output by the power management module; The first transceiver module leads out a pair of I2C buses on the first microprocessor module, buffers, drives and transmits and receives them, ensures that the I2C signal of the first microprocessor can be completely transmitted to the external display terminal; and can also receive the I2C signal from the display terminal.

[0022] The shielded cable is a four-channel transmission conductor with shielding function. The length is generally 0-30m. The four channels are specifically: Power line, connecting the instrument end and the display end. The power is generated by the power management module of the instrument end. The initial voltage is 3.3V, but it will be lost after being used by multiple modules and transmitted over long distances. SCL clock line, responsible for transmitting bidirectional clock signals; SCL data line, responsible for transmitting bidirectional data signals; Ground wire, the ground wire connecting the reference ground between the instrument end and the display end. This ground wire is not connected to the earth.

[0023] The display terminal includes: The second transceiver module leads out a pair of I2C buses on the second microprocessor module, buffers, drives, and transmits and receives them, ensuring that the I2C signal of the second microprocessor can be fully transmitted to the instrument end; and can also receive the I2C signal from the instrument end; The second microprocessor module is used to convert the I2C signal from the second transceiver module into a digital signal and transmit it to the display module; on the other hand, it receives the switch signal from the switch module, converts the switch signal into an I2C bus signal, and transmits it to the second transceiver module; A display screen module, used for processing the digital signal from the second microprocessor module and displaying it; The switch module is composed of a plurality of touch switches (buttons), which are pressed by the user to generate interactive commands and transmitted to the second microprocessor module; The boost switching power supply module is used to compensate the power supply voltage after long-distance transmission and stabilize it to 3.3V.

[0024] In summary, the working principle of this embodiment is as follows: First, power on the entire system, turn on the 24V power supply, and the power management module starts to operate, converting the 24V input power voltage into a more stable 3.3V voltage for basic power supply to each module. If there are other power requirements, the power module can be used to convert other voltages for power supply.

[0025] After the 3.3V voltage is generated, the first microprocessor module of the center starts to work. The first microprocessor module enables the sensors outside or inside the instrument to start collecting the physical quantities such as temperature, pressure, level, etc. that need to be collected, and then transmit them to the first microprocessor module.

[0026] The first microprocessor module converts it into a digital signal, and transmits it to the signal generator on the one hand. The signal generator (mainly a HART signal generator) modulates the signal into 1200 Hz (representing 1) and 2200 Hz (representing 0) signals, whose amplitude is generally ±0.5mA, and couples it to the 4-20mA current signal of the two-wire output of the power management module to output the signal; on the other hand, the digital signal can be used to control the 4-20mA output of the power management module, and can be further processed into an I2C bus signal inside the first microprocessor module and enter the first transceiver module.

[0027] After the I2C bus signal enters the first transceiver module, the first transceiver module buffers and drives it, and then together with a pair of 3.3V and ground power lines, it passes through a certain length of shielded line and enters the second transceiver module of the external display terminal. The 3.3V power signal line enters the boost switching power supply module for boosting, making it a regulated 3.3V power supply.

[0028] The second transceiver module transmits the I2C bus signal to the second microprocessor module, which performs analog-to-digital conversion on it. Then the digital signal enters the display module for display. The user can observe the temperature, level, pressure and other information measured by the instrument through the display screen, and can also view the measured curves and historical records.

[0029] At the same time, the above signal flows are reversible, so the user can operate through the button on the switch module of the display end. The switch signal will enter the second microprocessor module, which can participate in controlling the display function of the display screen, and can also enter the first microprocessor of the instrument end through the second transceiver module to participate in controlling the acquisition configuration of the sensor module. When the power is provided by the upper / lower computer, the signal transmitted from the display end can be coupled into the power line through the signal generation module to configure the upper / lower computer at a distance.

[0030] Secondly, when the power supply is not only an independent external power supply but the entire industrial control system, when the upper / lower computer wants to change the configuration of the instrument, the signal is directly coupled into the power line of the instrument, and enters the signal generating module after being decoupled by the power management module. The signal generating module demodulates the signal and then transmits it to the first microprocessor module. After receiving it, the first microprocessor module can control the change of the configuration of the sensor module, or transmit the signal through the first transceiver to the external display terminal, enter the second microprocessor module, and then communicate with the display module to change the content displayed on the display or the configuration of the interface.

[0031] Example 2 When the field environment has higher requirements on transmission distance and signal protection, it is necessary to perform incremental design of the transceivers on the instrument and display ends.

[0032] like Figure 2 As shown, the specific configuration of the first transceiver module and the second transceiver module after the external 50m shielded line is connected. At the same time, a relay transceiver is set in the middle of the shielded line to amplify the signal, thereby taking into account the extension of the signal transmission distance and the reliability of the signal transmission.

[0033] The configurations of the first transceiver module and the second transceiver module are exactly the same, and the first transceiver module is used as an example for explanation. The first transceiver module is powered by a 3.3V power supply and ground, and is connected to six signal lines, of which the upper left group of lines are the clock line and data line of the I2C bus, which are pulled high by larger resistors (K level) R1 and R2 respectively, and the lower left group of lines are transmission direction control signal lines, and the two lines correspond to the clock control signal and the data control signal respectively. When the pin input is "0", the transceiver only receives but does not send, and when the pin input is "1", the transceiver only sends but does not receive. The above control signal lines are only for external communication, that is, the communication between the instrument end and the display end; the internal communication is not controlled by the three-state gate, but is freely sent and received, that is, the communication between the first transceiver module and the first microprocessor module. Controlling the transmission and reception is to eliminate the risk and competition of the transmission and reception signals. Here, R3 and R4 are used to pull it down so that it can be stably maintained in a low-level state when there is no control signal input, that is, a state of only receiving but not transmitting, to ensure normal reception of signals; only when the pin inputs "1", it switches to a state of only transmitting but not receiving, and allows signals to be sent to the outside. The group of lines on the right side of the first transceiver module is connected to the relay transceiver, corresponding to the clock signal and data signal respectively, for external communication, and connected with external transmission lines. Because the line is long and has a high parasitic capacitance, smaller resistors (hundreds of ohms) R5 and R6 are required to pull it up.

[0034] There is a set of signal lines on both sides of the repeater transceiver, which are connected to the first transceiver module and the second transceiver module respectively. The connecting lines on the left and right sides are both 25 meters long, so smaller resistors (hundred ohms) R7-R10 are required to pull up for driving. The repeater transceiver is a slave transceiver, and there will be no risk or competition, so there is no need to control its transmission and reception.

[0035] For ease of understanding, two working states are given here: Not long after the circuit was powered on, the sensor module took a measurement and converted the data into an I2C bus signal through the first microprocessor module. At the same time, the first microprocessor module passed the command allowed to be sent to the first transceiver module. After receiving the command and the I2C bus signal, the first transceiver module drove it and passed it to the relay transceiver. The relay transceiver continued to drive and passed the I2C bus signal to the second transceiver module. At this time, the second transceiver module was in a state of receiving only and not sending. Therefore, after receiving the signal, it was passed to the second microprocessor module. The second microprocessor module turned on the display screen and began to display the test results of the sensor.

[0036] When the user operates through the button, the switch data is converted into an I2C bus signal through the second microprocessor module. At the same time, the second microprocessor transmits the command allowed to be sent to the second transceiver module. After receiving the command and the I2C bus signal, the second transceiver module drives it and transmits it to the relay transceiver. The relay transceiver continues to drive and transmits the I2C bus signal to the first transceiver module. At this time, the first transceiver module is in the state of only receiving but not sending. Therefore, after receiving the signal, it is transmitted to the first microprocessor module. At this time, the first microprocessor module can change the configuration of the sensor according to the signal command.

[0037] Example 3 like Figure 3 As shown, if the field end has a transmission requirement of more than 30m and is not suitable for multiple relays, the APL bus can be used to replace the I2C bus for signal transmission. The difference from Example 1 is that the first transceiver module and the second transceiver module are replaced by an APL module that can convert other signals into APL signals, and the four transmission lines connecting the two transceivers are replaced by a Category 4 cable composed of four twisted pairs. Due to the superiority of APL communication, the transmission distance can reach more than 100 meters.

[0038] The above is only a preferred specific embodiment of the present invention, which is an implementation method based on the overall concept of the present invention, and the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A wired operable display system for an instrument, characterized in that: include: A power supply, used to supply power to the system; The instrument side is used to measure various parameters of the instrument and convert them into I2C bus signals. After buffering and driving, they are sent to the The display end sends; Shielded wire, used as the transmission wire for I2C bus signal and power supply between the instrument end and the display end; The display end is used to receive the I2C bus signal, convert it into a digital signal, and then display it on the display screen.

2. A wired operable display system for an instrument according to claim 1, characterized in that: The instrument terminal comprises: A power management module, used for converting the input power into power available to each module, and outputting a 4-20mA current signal under the control of the first microprocessor module; Sensor module, used to measure various parameters of the instrument; The first microprocessor module is used to convert the analog signal measured by the sensor module into a digital signal, control the power management module to output a 4-20mA current signal according to the digital signal, and convert the 4-20mA current signal into an I2C bus signal; and transmit the digital signal to the first signal generating module; A first signal generating module is used to modulate the digital signal transmitted from the first microprocessor module and couple it to the 4-20mA current signal output by the power management module; The first transceiver module is used to buffer and drive the I2C bus signal of the first microprocessor module and then send it to the display end.

3. A wired operable display system for an instrument according to claim 2, characterized in that: The first signal generating module is further used to decouple the analog signal transmitted on the I2C bus from the power management module, and to demodulate the analog signal and transmit it to the first microprocessor module.

4. The wired operable display system for an instrument according to claim 2, characterized in that: The first transceiver module is also used to receive an I2C bus signal from the display end.

5. The wired operable display system for an instrument according to claim 1, characterized in that: The display terminal comprises: A second transceiver module is used to receive the I2C bus signal from the instrument end and transmit it to the second microprocessor module; The second microprocessor module is used to convert the I2C signal from the second transceiver module into a digital signal and transmit it to the display screen module; The display screen module is used for processing the digital signal from the second microprocessor module and then displaying it.

6. A wired operable display system for an instrument according to claim 5, characterized in that: The display terminal comprises: The switch module is used to receive the switch signal input by the user and transmit it to the second microprocessor module; the second microprocessor module is also used to convert the switch signal into an I2C bus signal and transmit it to the second transceiver module; the second transceiver module is also used to buffer and drive the I2C bus signal from the second microprocessor module and send it to the instrument end.

7. The wired operable display system for an instrument according to claim 5, characterized in that: The display terminal comprises: The boost switch power supply module is used to boost the power supply from the instrument end to the voltage required by the display end.

8. The wired operable display system for an instrument according to claim 1, characterized in that: It comprises a relay transceiver, the instrument end and the display end are both provided with transceivers, and the relay transceiver is connected to the two transceivers through the shielded wire.

9. A wired operable display system for an instrument according to claim 8, characterized in that: An I2C bus and a control signal line are provided between the instrument end and its transceiver, and between the display end and its transceiver. The control signal line is used to control the transceiver state.

10. The wired operable display system for an instrument according to claim 1, characterized in that: The APL bus is used for signal transmission between the instrument end and the display end.

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