Output diagnostic control circuit of a transmitter and transmitter

Abstract

The present invention discloses an output diagnostic control circuit of a transmitter and a transmitter. The output diagnostic control circuit of the transmitter includes: a power supply current limiting circuit, the first end and the second end of the power supply current limiting circuit are respectively connected to a first connection terminal and the input end of a DC / DC module, and the output end of the DC / DC module outputs a power supply to supply power to the transmitter; a power supply control circuit is used to control whether to bypass the power supply current limiting circuit according to a first control signal input at a control terminal; an output control circuit is used to control an adjusted current output according to the first control signal; the input end of a current output circuit is connected to the output end of the output control circuit, and generates an output current of the transmitter according to a second control signal corresponding to a measurement signal received at the control terminal. The present invention can achieve rapid detection of faults of the transmitter and safely output a fault current, thereby helping to ensure that the safety system can be repaired in time.

Description

Technical Field

[0001] The present invention relates to the technical field of transmitters, and particularly to an output diagnostic control circuit and a transmitter for a transmitter. Background Art

[0002] In recent years, with the development of the petroleum, chemical, and machinery industries, industrial instruments not only need to meet functional requirements but also safety requirements. The functional safety design of industrial instruments has become the goal that domestic instrument manufacturers have been constantly pursuing. The function of industrial instruments is to measure signals such as on-site temperature and pressure, and linearly convert them into 4-20 mA current signals and send them to the backend safety system. The safety system of industrial on-site instruments includes an output diagnostic control circuit containing a transmitter. The output diagnostic control circuit determines whether there is a fault in the on-site measurement signal or inside the industrial instrument by detecting the magnitude of the 4-20 mA output current, so as to achieve the purposes of timely maintenance, safe shutdown, etc.

[0003] Existing output diagnostic control circuits of transmitters often define the 4-20 mA current range as the normal signal range, and currents less than or equal to 3.6 mA or greater than or equal to 21.5 mA as fault currents. When the output diagnostic control circuit of the transmitter detects a fault current, it triggers an alarm signal and issues a shutdown action or an alarm for maintenance through the control unit.

[0004] Existing output diagnostic control circuits of transmitters cannot detect fault signals in a timely manner, are difficult to output fault currents, and cannot ensure that the safety system can be repaired in a timely manner. Summary of the Invention

[0005] The present invention provides an output diagnostic control circuit and a transmitter for a transmitter. The output diagnostic control circuit of the transmitter can achieve rapid detection of transmitter faults and safely output fault currents, thereby helping to ensure that the safety system can be repaired in a timely manner.

[0006] In a first aspect, an output diagnostic control circuit for a transmitter provided by an embodiment of the present invention includes: a power supply current limiting circuit, the power supply current limiting circuit includes a first end and a second end, the first end and the second end of the power supply current limiting circuit are respectively connected to a first terminal and the input end of a DC / DC module, and the output end of the DC / DC module outputs a power supply to supply power to the transmitter; a power supply control circuit, the power supply control circuit includes a control end, a first end and a second end, the first end and the second end of the power supply control circuit are respectively connected to the first end and the second end of the power supply current limiting circuit; the power supply control circuit is used to control whether the power supply current limiting circuit is bypassed according to a first control signal input at the control end; an output control circuit, the control end of the output control circuit is used to input the first control signal, and the output control circuit is used to control the regulated current output according to the first control signal; a current output circuit, the current output circuit includes a control end and an input end, the input end of the current output circuit is connected to the output end of the output control circuit, and generates an output current of the transmitter according to a second control signal corresponding to the measurement signal received at the control end.

[0007] Optionally, it further includes a power supply monitoring circuit, the input end of the power supply monitoring circuit is connected to the output end of the DC / DC module, and the output end of the power supply monitoring circuit is connected to the control end of the power supply control circuit and the control end of the output control circuit, and is used to control the power supply control circuit and the output control circuit to turn off when the power supply output by the DC / DC module is abnormal.

[0008] Optionally, it further includes a control module, a V / I conversion circuit and a sampling circuit; the control signal output end of the control module is connected to the input end of the V / I conversion circuit, and the output end of the V / I conversion circuit is connected to the control end of the current output circuit; the V / I conversion circuit is used to convert a voltage signal into a current signal to output a second control signal to the current output circuit; the sampling circuit is connected between the current output circuit and a second terminal, and the output end of the sampling circuit is connected to the control module, and is used to collect the output current; wherein, the first terminal is used as the positive power supply input, and the second terminal is used as the negative power supply input.

[0009] Optionally, it further includes a reset latch circuit and an AND gate circuit; the reset latch circuit is connected to the reset end of the control module, and is used to detect a jump signal at the reset end of the control module and latch it as a fixed level; the first input end of the AND gate circuit is connected to the output end of the reset latch circuit, the second input end of the AND gate circuit is connected to the second control signal output end of the control module, and the output end of the AND gate circuit is connected to the control end of the power supply control circuit and the control end of the output control circuit.

[0010] Optionally, the power current limiting circuit includes a first resistor, a second resistor, a zener diode, and a first triode; the collector of the first triode is connected to the first terminal, the first end of the second resistor is connected to the first terminal, the second end of the second resistor is connected to the base of the first triode and the cathode of the zener diode, the reference signal terminal of the zener diode is connected to the emitter of the first triode and the first end of the first resistor, and the anode of the zener diode and the second end of the first resistor are connected to the input terminal of the DC / DC module.

[0011] Optionally, the power control circuit includes a third resistor, a fourth resistor, a fifth resistor, a second triode, and a first MOS transistor; the first and second poles of the first MOS transistor are respectively connected to the first and second terminals of the power current limiting circuit; the first end of the third resistor is connected to the first pole of the first MOS transistor, and the second end of the third resistor is connected to the gate of the first MOS transistor; the first end of the fourth resistor is connected to the gate of the first MOS transistor, the second end of the fourth resistor is connected to the collector of the second triode, the emitter of the second triode is grounded, and the base of the second triode is connected to the control terminal of the power control circuit; the first end of the fifth resistor is connected to the base of the second triode, and the second end of the fifth resistor is connected to the first terminal.

[0012] Optionally, the output control circuit includes a sixth resistor, a seventh resistor, a third triode, and a second MOS transistor; the first end of the sixth resistor and the first pole of the second MOS transistor are connected to the first terminal, the second end of the sixth resistor is connected to the gate of the second MOS transistor, and the second pole of the second MOS transistor is connected to the input terminal of the current output circuit; the first end of the seventh resistor is connected to the gate of the second MOS transistor, the second end of the seventh resistor is connected to the collector of the third triode, the emitter of the third triode is grounded, and the base of the third triode is connected to the control terminal of the output control circuit.

[0013] Optionally, the current output circuit includes a fourth triode and an eighth resistor; the base of the fourth triode is connected to the control terminal of the current output circuit, the collector of the fourth triode is connected to the output terminal of the output control circuit, the first end of the eighth resistor is connected to the emitter of the fourth triode and grounded, and the second end of the eighth resistor is connected to the output terminal of the current output circuit.

[0014] Optionally, the sampling circuit includes a ninth resistor, the first end of the ninth resistor is connected to the output terminal of the current output circuit, and the second end of the ninth resistor is connected to the second terminal.

[0015] In a second aspect, an embodiment of the present invention further provides a transmitter, and the transmitter includes the output diagnostic control circuit of the transmitter provided in the first aspect.

[0016] The output diagnostic control circuit of the transmitter provided by the embodiment of the present invention includes a power supply current limiting circuit, a power supply control circuit, an output control circuit, and a current output circuit. The first control signal input through the output control circuit can control the regulated current output; the second control signal corresponding to the measurement signal received at the control terminal of the current output circuit can generate the output current of the transmitter. By detecting the output current of the transmitter, rapid detection of the transmitter failure can be achieved, and the fault current can be safely output, thereby helping to ensure that the safety system can be repaired in a timely manner.

[0017] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the present invention, nor is it used to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. Brief Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for use in the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0019] Figure 1 It is a schematic structural diagram of an output diagnostic control circuit of a transmitter provided by an embodiment of the present invention;

[0020] Figure 2 It is a schematic structural diagram of another output diagnostic control circuit of a transmitter provided by an embodiment of the present invention;

[0021] Figure 3 It is a schematic structural diagram of another output diagnostic control circuit of a transmitter provided by an embodiment of the present invention;

[0022] Figure 4 It is a power-on working timing diagram of an output diagnostic control circuit of a transmitter provided by an embodiment of the present invention. Detailed Embodiments

[0023] In order to enable those skilled in the art to better understand the solution of the present invention, the following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0024] It should be noted that in the description of the present invention, the terms "first", "second", etc. in the specification, claims and the above drawings are used to distinguish similar objects, and do not necessarily describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present invention described here can be implemented in an order other than those illustrated or described here. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device comprising a series of steps or units does not necessarily limit to those clearly listed steps or units, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0025] As described in the background art, when the independent power supply type transmitter detects an output current fault, it can generally directly cut off the power supply of the output circuit to achieve the purpose of outputting a current less than 3.6 mA. Different from the independent power supply type transmitter, the output loop power supply type transmitter directly intercepts current on the 4-20 mA output current to provide energy for the entire circuit. The 4-20 mA output current includes two parts: the regulated current and the power consumption current. Based on this, for the diagnosis of the output current of the output loop power supply type transmitter, various faults that cause the power consumption current to become larger or smaller also need to be considered. Different from the independent power supply instrument, when directly cutting off the power supply of the output circuit, it is often impossible to output a fault current less than 3.6 mA at this time, so that the safety system cannot detect the fault signal in time, resulting in additional losses.

[0026] Based on the above problems, the embodiment of the present invention provides an output diagnostic control circuit for a transmitter, and this embodiment is applicable to the situation of detecting transmitter faults. Figure 1 It is a schematic structural diagram of an output diagnostic control circuit for a transmitter provided by an embodiment of the present invention. As Figure 1 shown, the output diagnostic control circuit of this transmitter includes:

[0027] A power supply current limiting circuit 10, the power supply current limiting circuit 10 includes a first terminal AIN and a second terminal AOUT. The first terminal AIN and the second terminal AOUT of the power supply current limiting circuit 10 are respectively connected to the first terminal POWER+ and the input terminal IN of the DC / DC module. The output terminal OUT of the DC / DC module U1 outputs a power supply VCC to supply power to the transmitter.

[0028] Power control circuit 20, the power control circuit 20 includes a control terminal CE1, a first terminal CIN1 and a second terminal CIN2. The first terminal CIN1 and the second terminal CIN2 of the power control circuit 20 are respectively connected to the first terminal AIN and the second terminal AOUT of the power current limiting circuit 10. The power control circuit 20 is used to control whether to bypass the power current limiting circuit 10 according to the first control signal OUTPUT_CTRL input by the control terminal CE1.

[0029] Output control circuit 30, the control terminal CE2 of the output control circuit 30 is used to input the first control signal OUTPUT_CTRL, and the output control circuit 30 is used to control the regulated current output according to the first control signal OUTPUT_CTRL.

[0030] Current output circuit 40, the current output circuit 40 includes a control terminal CE3 and an input terminal BIN. The input terminal BIN of the current output circuit 40 is connected to the output terminal COUT of the output control circuit 30, and generates the output current of the transmitter according to the second control signal corresponding to the measurement signal received by the control terminal CE3. The output current of the transmitter is the actual output current i of the transmitter.

[0031] The actual output current i of the transmitter consists of two parts. One part is the regulated current i1, and the other part is the power consumption current i2 of the power current limiting circuit 10. That is, the actual output current i = regulated current i1 + power consumption current i2, where the regulated current i1 is greater than or equal to 0, and the power consumption current i2 should be less than 3.6 mA during design. The specific size of the power consumption current i2 varies according to the manufacturer's circuit design. Only in this way can the regulated current i1 be changed according to the size of the input signal when there is no fault, ensuring that the actual output current i can be adjusted within the range of 4 - 20 mA. And when there is a fault, when the regulated current i1 is minimized to 0, the actual output current i is equal to the power consumption current i2, that is, the actual output current of the transmitter is made less than 3.6 mA through the power current limiting circuit 10.

[0032] Among them, the power current limiting circuit 10 is a circuit capable of limiting current. When the current limiting circuit 10 works, it limits the power consumption of the power supply within 3.6 mA. The power current limiting circuit is also used to prevent the DC - DC module U1 from being damaged due to excessive input current. The structure of the power current limiting circuit 10 can be various.

[0033] The output control circuit 30 further includes an input terminal CIN, and the input terminal CIN of the output control circuit 30 is connected to the first terminal POWER +.

[0034] The first control signal OUTPUT_CTRL can be a signal output by a power supply monitoring chip for monitoring the magnitude of the output power VCC at the output terminal OUT of the DC / DC module U1. Exemplarily, when the output power VCC of the DC / DC module U1 is under-voltage or over-voltage, the first control signal OUTPUT_CTRL output by the power supply monitoring chip is at a low level. When the output power VCC of the DC / DC module U1 is normal, the first control signal OUTPUT_CTRL output by the power supply monitoring chip is at a high level.

[0035] The second control signal can be a 4-20 mA current signal corresponding to the measurement signal. After the collected measurement signal is processed by the microprocessor, it is transmitted to the conversion circuit. The conversion circuit converts the voltage signal into a current signal to output the second control signal to the current output circuit 40.

[0036] The working principle of the output diagnostic control circuit of the transmitter is as follows:

[0037] When the output power VCC of the DC / DC module U1 is under-voltage or over-voltage, the first control signal OUTPUT_CTRL is at an invalid level, the power supply control circuit 20 and the output control circuit 30 are turned off, and the power supply current limiting circuit 10 works. At this time, the regulated current i1 output by the output control circuit 30 is equal to 0, and the power supply current limiting circuit 10 limits the power consumption current i2 of the power supply current limiting circuit to be less than 3.6 mA. At this time, the actual output current i of the transmitter is equal to the power consumption current i2 of the power supply current limiting circuit. By detecting the output current of the transmitter, a quick detection of the transmitter fault can be achieved. When the power supply monitoring circuit 50 detects that the output power VCC of the DC / DC module U1 is normal, the first control signal OUTPUT_CTRL is at an effective level, the power supply control circuit 20 is turned on, bypassing the power supply current limiting circuit 10. In other words, when the power supply control circuit 20 is turned on, the power supply current limiting circuit 10 is short-circuited. At the same time, when the output power VCC of the DC / DC module U1 is normal, the output control circuit 30 is turned on. At this time, the actual output current i of the transmitter = regulated current i1 + power consumption current i2 of the power supply current limiting circuit. The current output circuit 40 normally outputs the output current of the transmitter according to the second control signal corresponding to the measurement signal received at the control terminal CE3.

[0038] The output diagnostic control circuit of the transmitter provided by the embodiment of the present invention includes a power supply current limiting circuit, a power supply control circuit, an output control circuit, and a current output circuit. The regulated current output can be controlled by the first control signal input to the output control circuit; the output current of the transmitter can be generated by the second control signal corresponding to the measurement signal received at the control terminal of the current output circuit. By detecting the output current of the transmitter, a quick detection of the transmitter fault can be achieved, and the fault current can be safely output, thus helping to ensure that the safety system can be repaired in time.

[0039] Figure 2 This is a schematic diagram of the output diagnostic control circuit of another transmitter provided by an embodiment of the present invention, which is further optimized and extended based on the above embodiment.

[0040] As Figure 2 shown, optionally, the output diagnostic control circuit of the transmitter further includes a power supply monitoring circuit 50. The input end IN1 of the power supply monitoring circuit 50 is connected to the output end OUT of the DC / DC module U1. The output end OUT1 of the power supply monitoring circuit 50 is connected to the control end CE1 of the power supply control circuit 20 and the control end CE2 of the output control circuit 30, and is used to control the power supply control circuit 20 and the output control circuit 30 to turn off when the power supply output by the DC / DC module U1 is abnormal.

[0041] The power supply terminal of the power supply monitoring circuit 50 is connected to the first terminal POWER+, and the external power supply provides the working power supply for the power supply monitoring circuit 50.

[0042] The power supply VCC output by the DC / DC module U1 serves as the working power supply for the control module U2, the V / I conversion circuit 60, the sampling circuit 70, the reset latch circuit 80, and the AND gate circuit 90.

[0043] The power supply monitoring circuit 50 includes a power supply monitoring chip, and the output pin of the power supply monitoring chip is the output end OUT1 of the power supply monitoring circuit 50.

[0044] The output diagnostic control circuit of the transmitter further includes a control module U2, a V / I conversion circuit 60, and a sampling circuit 70.

[0045] The control signal output terminal PWM of the control module U2 is connected to the input end IN2 of the V / I conversion circuit 60. The output end OUT2 of the V / I conversion circuit 60 is connected to the control end CE3 of the current output circuit 40. The V / I conversion circuit 60 is used to convert the voltage signal into a current signal to output a second control signal to the current output circuit 40.

[0046] The sampling circuit 70 is connected between the current output circuit 40 and the second terminal POWER-. The output end OUT3 of the sampling circuit 70 is connected to the control module U2, and is used to collect the actual output current i.

[0047] Among them, the first terminal POWER+ serves as the positive power input terminal, and the second terminal POWER- serves as the negative power input terminal.

[0048] The control module U2 may include a micro control unit. Optionally, the control module U2 may include a single-chip microcomputer, and may also include a Digital Signal Processor (DSP) or a Field Programmable Gate Array (FPGA). The control module U2 precisely controls the actual output current i of the transmitter by changing the duty cycle of the pulse width modulation signal (voltage signal).

[0049] The V / I conversion circuit 60 converts the voltage signal (pulse width modulation signal) output by the control module U2 into a 4 - 20 mA current signal.

[0050] The output diagnostic control circuit of the transmitter further includes a reset latch circuit 80 and an AND gate circuit 90.

[0051] The reset latch circuit 80 is connected to the reset terminal / NRST of the control module U2, and is used to detect the jump signal of the reset terminal / NEST of the control module U2 and latch it into a fixed level.

[0052] The first input terminal RIN1 of the AND gate circuit 90 is connected to the output terminal NRST of the reset latch circuit 80, the second input terminal RIN2 of the AND gate circuit 90 is connected to the second control signal output terminal GPIO of the control module U2, and the output terminal ROUT of the AND gate circuit 90 is connected to the control terminal CE1 of the power control circuit 20 and the control terminal CE2 of the output control circuit 30.

[0053] Among them, the reset latch circuit 80 is a storage unit circuit sensitive to pulse levels, and can change its state under the action of a specific input pulse level. The reset latch circuit 80 detects the falling edge signal of the output signal of the control module U2 and latches it into a low level output.

[0054] The AND gate circuit 90 is a basic logic gate circuit that performs the "AND" operation. The AND gate circuit 90 has two input terminals and one output terminal. When all the inputs of the AND gate circuit 90 are simultaneously at a high level (logic 1), the output is at a high level; otherwise, the output is at a low level (logic 0).

[0055] In the embodiment of the present invention, the working principle of the output diagnostic control circuit of the transmitter is as follows:

[0056] The power supply VCC output from the output terminal OUT of the DC / DC module U1 is transmitted to the input terminal IN1 of the power supply monitoring circuit 50. When the power supply monitoring circuit 50 detects an abnormality (undervoltage or overvoltage) in the power supply VCC output by the DC-DC module U1, the power supply monitoring circuit 50 outputs an invalid level, causing the power supply control circuit 20 and the output control circuit 30 to turn off. The power supply current limiting circuit 10 operates. At this time, the regulated current i1 output by the output control circuit 30 is equal to 0, and the power supply current limiting circuit 10 limits the power consumption current i2 of the power supply current limiting circuit to less than 3.6 mA. At this time, the actual output current i of the transmitter is equal to the power consumption current i2 of the power supply current limiting circuit, that is, the actual output current i of the transmitter is less than 3.6 mA. By detecting the output current of the transmitter, rapid detection of transmitter faults can be achieved.

[0057] When the power supply VCC output by the DC / DC module U1 is normal and the control module U2 fails, due to the failure of the control module U2, that is, the counter in the control module U2 cannot be reset, so its count will exceed a certain value. The watchdog in the control module U2 attempts to reset the control module U2 by outputting a low-level pulse from the reset terminal / NEST. This low-level pulse is transmitted to the reset latching circuit 80. The reset latching circuit 80 detects the transition signal of the reset terminal / NEST of the control module U2 and latches and outputs a low-level signal. The AND gate circuit 90 outputs a low level, the power supply control circuit 20 and the output control circuit 30 turn off, and the power supply current limiting circuit operates. At this time, the actual output current i of the transmitter is equal to the power consumption current i2 of the power supply current limiting circuit, less than 3.6 mA, which is the fault current, completing the fault diagnosis and output control in this situation.

[0058] When the power supply VCC output by the DC / DC module U1 is normal and the control module U2 works normally, when the actual output current i of the transmitter is too large due to a failure of the V / I conversion circuit 60, a failure of the control signal output terminal PWM of the control module U2, or an increase in the power consumption current of the power supply current limiting circuit 10. The analog input terminal AIN of the control module U2 collects the current of the current output circuit 40 in real time through the sampling circuit 70 to obtain the actual output current i. The control module U2 obtains the theoretical output current iref of the input measurement value according to the functional relationship between the input measurement value and the theoretical output current iref. When the control module U2 detects that the current difference between the actual output current minus the theoretical output current exceeds the preset threshold. Exemplarily, the set preset threshold is 0.32 mA, the actual output current i is 13 mA, and the theoretical output current iref is 12 mA. At this time, the actual output current i - the theoretical output current iref = 1 mA, which is greater than the preset threshold of 0.32 mA. The control module U2 changes the duty cycle of the pulse width modulation signal (voltage signal) so that the theoretical output current output by the control signal output terminal PWM is 21.5 mA. At this time, the actual output current i sampled back through the sampling circuit 70 is a current greater than 21.5 mA.

[0059] When the power supply VCC output by the DC / DC module U1 is normal and the control module U2 works normally, when the actual output current i of the transmitter is too small due to a failure of the V / I conversion circuit 60, a failure of the control signal output terminal PWM of the control module U2, etc. The analog input terminal AIN of the control module U2 collects the current of the current output circuit 40 in real time through the sampling circuit 70 to obtain the actual output current i. The control module U2 obtains the theoretical output current iref of the input measurement value according to the functional relationship between the input measurement value and the theoretical output current iref. When the control module U2 detects that the current difference between the theoretical output current iref minus the actual output current i exceeds the preset threshold, the control module U2 changes the duty cycle of the pulse width modulation signal (voltage signal) so that the theoretical output current iref output by the control signal output terminal PWM is 3.6 mA. At this time, the actual output current i sampled back through the sampling circuit 70 is a current less than 3.6 mA.

[0060] When the power supply VCC output by the DC / DC module U1 is normal and the control module U2 works properly, the actual output current i remains fixed and is any value within the range of 4 - 20 mA due to faults such as the V / I conversion circuit 60 failure, the PWM failure of the control signal output terminal of the control module U2, etc. Specifically, the analog input terminal AIN of the control module U2 samples the actual output current i for the first time through the sampling circuit 70. When the absolute value of the current difference between the detected actual output current i and the theoretical output current iref is higher than the preset threshold, at this time, the theoretical output current iref of the control signal output terminal of the control module U2 is 21.5 mA or 3.6 mA, but the actual output current i sampled back by the sampling circuit 70 is a fixed current. At this time, the analog input terminal AIN of the control module U2 samples the actual output current i for the second time through the sampling circuit 70. When the control module U2 detects that the second actual output current i is not greater than 21.5 mA or less than 3.6 mA, the control module U2 controls the second control signal output terminal GPIO to output an invalid level (low level), the AND gate circuit 90 outputs an invalid level, the first control signal OUTPUT_CTRL is an invalid level, the power supply control circuit 20 and the output control circuit 30 are turned off, and the power supply current limiting circuit 10 works. At this time, the regulated current i1 output by the output control circuit 30 is equal to 0, and the power supply current limiting circuit 10 limits the power consumption current i2 of the power supply current limiting circuit to less than 3.6 mA. At this time, the actual output current i of the transmitter is equal to the power consumption current i2 of the power supply current limiting circuit. By detecting the output current of the transmitter, the rapid detection of the transmitter fault can be realized.

[0061] The output diagnostic control circuit of the transmitter provided by the embodiment of the present invention can detect various faults that cause abnormal actual output current through a combination of hardware and software, and can safely output a fault current less than or equal to 3.6 mA or greater than or equal to 21.5 mA, which helps to ensure that the safety system can be repaired in time and can provide a high-level diagnostic coverage rate.

[0062] Figure 3 It is a schematic structural diagram of another output diagnostic control circuit of the transmitter provided by the embodiment of the present invention, which is further optimized and extended based on the above embodiment.

[0063] As Figure 3 shown, the power supply current limiting circuit 10 includes a first resistor R1, a second resistor R2, a zener diode D1, and a first triode Q1.

[0064] The collector of the first triode Q1 is connected to the first terminal POWER+. The first end of the second resistor R2 is connected to the first terminal POWER+. The second end of the second resistor R2 is connected to the base of the first triode Q1 and the cathode of the voltage regulator diode D1. The reference signal terminal of the voltage regulator diode D1 is connected to the emitter of the first triode Q1 and the first end of the first resistor R1. The anode of the voltage regulator diode D1 and the second end of the first resistor R1 are connected to the input terminal IN of the DC / DC module U1.

[0065] The anode of the voltage regulator diode D1 and the second end of the first resistor R1 are the second end AOUT of the power supply current limiting circuit 10. The first end of the second resistor R2 is the first end AIN of the power supply current limiting circuit 10.

[0066] The power supply control circuit 20 includes a third resistor R3, a fourth resistor R4, a fifth resistor R5, a second triode Q2, and a first MOS transistor M1.

[0067] The first pole and the second pole of the first MOS transistor M1 are respectively connected to the first end AIN and the second end AOUT of the power supply current limiting circuit 10.

[0068] The first end of the third resistor R3 is connected to the first pole of the first MOS transistor M1, and the second end of the third resistor R3 is connected to the gate of the first MOS transistor M1; the first end of the fourth resistor R4 is connected to the gate of the first MOS transistor M1, the second end of the fourth resistor R4 is connected to the collector of the second triode Q2, the emitter of the second triode Q2 is grounded to GND, and the base of the second triode Q2 is connected to the control terminal CE1 of the power supply control circuit 20; the first end of the fifth resistor R5 is connected to the base of the second triode Q2, and the second end of the fifth resistor R5 is connected to the first terminal POWER+.

[0069] The power supply control circuit 20 further includes a first capacitor C1. The first end of the first capacitor C1 is connected to the base of the second triode Q2, and the second end of the first capacitor C1 is connected to the emitter of the second triode Q2.

[0070] The first pole of the first MOS transistor M1 is the first end CIN1 of the power supply control circuit 20, and the second pole of the first MOS transistor M1 is the second end CIN2 of the power supply control circuit 20.

[0071] The output control circuit 30 includes a sixth resistor R6, a seventh resistor R7, a third triode Q3, and a second MOS transistor M2.

[0072] The first end of the sixth resistor R6 and the first pole of the second MOS transistor M2 are connected to the first terminal POWER+. The second end of the sixth resistor R6 is connected to the gate of the second MOS transistor M2. The second pole of the second MOS transistor M2 is connected to the input terminal BIN of the current output circuit 40. The first end of the seventh resistor R7 is connected to the gate of the second MOS transistor M2. The second end of the seventh resistor R7 is connected to the collector of the third triode Q3. The emitter of the third triode Q3 is grounded to GND. The base of the third triode Q3 is connected to the control terminal CE2 of the output control circuit 30.

[0073] The first end of the sixth resistor R6 and the first pole of the second MOS transistor M2 are the input terminal CIN of the output control circuit 30. The second pole of the second MOS transistor M2 is the output terminal COUT of the output control circuit 30.

[0074] The current output circuit 40 includes a fourth triode Q4 and an eighth resistor R8.

[0075] The base of the fourth triode Q4 is connected to the control terminal CE3 of the current output circuit 40. The collector of the fourth triode Q4 is connected to the output terminal COUT of the output control circuit 30. The first end of the eighth resistor R8 is connected to the emitter of the fourth triode Q4 and grounded to GND. The second end of the eighth resistor R8 is connected to the output terminal of the current output circuit 40.

[0076] The collector of the fourth triode Q4 is the input terminal BIN of the current output circuit 40.

[0077] The sampling circuit 70 includes a ninth resistor R9. The first end of the ninth resistor R9 is connected to the output terminal of the current output circuit 40. The second end of the ninth resistor R9 is connected to the second terminal POWER-.

[0078] The sampling circuit 70 further includes an output current feedback circuit 710. The first end of the output current feedback circuit 710 is connected to the second end of the ninth resistor R9. The second end of the amplifier module U3 is connected to the V / I conversion circuit 60. The output terminal of the output current feedback circuit 710 is connected to the output terminal OUT3 of the sampling circuit 70. The output current feedback circuit 710 is used to amplify the current signal collected by the ninth resistor R9 into a voltage signal and filter the voltage signal. The output terminal OUT3 of the sampling circuit 70 is connected to the control module U2 and is used to collect the actual output current i of the transmitter.

[0079] The control module U2 further includes a tenth resistor R10, an eleventh resistor R11, and a second capacitor C2.

[0080] The first end of the tenth resistor R10 is connected to the reset terminal / NRST of the control module U2, and the second end of the tenth resistor R10 is connected to the power supply VCC output by the DC / DC module U1. The first end of the second capacitor C2 is connected to the reset terminal / NRST of the control module U2, and the second end of the second capacitor C2 is grounded to GND. The first end of the eleventh resistor R11 is connected to the second control signal output terminal GPIO of the control module U2, and the second end of the eleventh resistor R11 is connected to the power supply VCC output by the DC / DC module U1.

[0081] The specific connection manners of the power supply current limiting circuit 10, the power supply control circuit 20, the output control circuit 30, the current output circuit 40, the power supply monitoring circuit 50, the V / I conversion circuit 60, the sampling circuit 70, the reset latching circuit 80, the AND gate circuit 90, the DC - DC module U1 and the control module U3 are the same as Figure 2 the connection manner of the output diagnostic control circuit of the transmitter in

[0082] In this embodiment, the working principle of the output diagnostic control circuit of the transmitter is as follows:

[0083] When the power supply VCC output by the DC / DC module U1 is under - voltage or over - voltage, the first control signal OUTPUT_CTRL is at a low level, the second triode Q2 and the third triode Q3 are turned off. When the second triode Q2 and the third triode Q3 are turned off, the first MOS transistor M1 and the second MOS transistor M2 are cut off, that is, the power supply control circuit 20 and the output control circuit 30 are turned off, and the first triode Q1 is turned on, that is, the power supply current limiting circuit 10 works. At this time, the regulated current i1 output by the output control circuit 30 is equal to 0, and the power supply current limiting circuit 10 limits the power consumption current i2 of the power supply current limiting circuit to less than 3.6 mA. At this time, the actual output current i of the transmitter is equal to the power consumption current i2 of the power supply current limiting circuit. By detecting the output current of the transmitter, the rapid detection of the transmitter fault can be realized. When the power supply monitoring circuit 50 detects that the power supply VCC output by the DC / DC module U1 is normal, the first control signal OUTPUT_CTRL is at a high level, the second triode Q2 is turned on, and the first MOS transistor M1 is turned on, that is, the power supply control circuit 20 is turned on, bypassing the power supply current limiting circuit 10. In other words, when the power supply control circuit 20 is turned on, the power supply current limiting circuit 10 is short - circuited. At the same time, when the power supply VCC output by the DC / DC module U1 is normal, the third triode Q3 is turned on, and the second MOS transistor M2 is turned on, that is, the output control circuit 30 is turned on. At this time, the actual output current i of the transmitter = regulated current i1+power consumption current i2 of the power supply current limiting circuit. The current output circuit 40 normally outputs the 4 - 20 mA current signal output by the V / I conversion circuit 60.

[0084] Figure 4It is the power-on working timing diagram of an output diagnostic control circuit of a transmitter provided by an embodiment of the present invention.

[0085] The external power supply is connected to the output diagnostic control circuit through the first terminal POWER+ and the second terminal POWER-. At this time, the first power supply POWER is established. The first terminal POWER+ of the first power supply POWER is connected to the power supply monitoring circuit 50 to supply power to the power supply monitoring circuit 50. The power supply VCC output by the DC-DC module U1 is 0. At this time, the input terminal of the power supply monitoring circuit 50 detects that the power supply VCC output by the DC-DC module U1 is under voltage, and the output terminal OUT1 of the power supply monitoring circuit 50 outputs a low level; the working power supply of the control module U2 is the power supply VCC output by the DC-DC module U1. At this time, the control module U2 has not worked yet, so its second control signal output terminal GPIO and the reset terminal / NRST are both at a low level. The working power supply of the reset latch circuit 80 and the AND gate circuit 90 is the power supply VCC output by the DC-DC module U1. At this time, the reset latch circuit 80 has not worked yet, and the output terminal NRST of the reset latch circuit 80 is at a low level. The AND gate circuit 90 outputs a low level signal, that is, the first control signal OUTPUT_CTRL is a low level signal, and the second triode Q2 and the third triode Q3 are turned off. The power supply control circuit 20 and the output control circuit 30 are turned off, and the power supply current limiting circuit 10 works. At this time, the regulated current i1 output by the output control circuit 30 is equal to 0. The power supply current limiting circuit 10 limits the power supply current limiting circuit power consumption current i2 to less than 3.6 mA. At this time, the actual output current i of the transmitter is equal to the power supply current limiting circuit power consumption current i2. By detecting the output current of the transmitter, the rapid detection of the transmitter fault can be realized.

[0086] After the power supply VCC output by the DC-DC module U1 is established, the power supply monitoring circuit 50 monitors that the power supply VCC output by the DC-DC module U1 is within the normal range. The output terminal OUT1 of the power supply monitoring circuit 50 outputs a high level through the fifth resistor R5; at the same time, the reset terminal / NRST of the control module U2 rises to a high level; the reset latch circuit 80 works, and the output terminal NRST of the reset latch circuit 80 outputs a high level; both the first input terminal RIN1 and the second input terminal RIN2 of the AND gate circuit 90 are at a high level, and the output terminal ROUT of the AND gate circuit 90 outputs a high level through the fifth resistor R5; finally, the first control signal OUTPUT_CRTL is at a high level; the power supply control circuit 20 is turned on to bypass the power supply current limiting circuit 10. The output control circuit 30 is turned on. At this time, the actual output current i = regulated current i1 + power consumption current i2. The transmitter converts the measurement signal into a 4-20 mA current and outputs it normally according to the magnitude of the measurement signal.

[0087] An embodiment of the present invention further provides a transmitter, including the output diagnostic control circuit of the transmitter in any of the above embodiments, and having a functional circuit and beneficial effects corresponding to the output diagnostic control circuit of the transmitter.

[0088] The above specific embodiments do not constitute a limitation to the protection scope of the present invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. An output diagnostic control circuit for a transmitter, characterized in that, Comprising: A power supply current limiting circuit, the power supply current limiting circuit includes a first end and a second end, the first end and the second end of the power supply current limiting circuit are respectively connected to a first wiring terminal and the input end of a DC / DC module, and the output end of the DC / DC module outputs a power supply to supply power to the transmitter; A power supply control circuit, the power supply control circuit includes a control end, a first end and a second end, the first end and the second end of the power supply control circuit are respectively connected to the first end and the second end of the power supply current limiting circuit; the power supply control circuit is used to control whether the power supply current limiting circuit is bypassed according to a first control signal input at the control end; An output control circuit, the control end of the output control circuit is used to input the first control signal, and the output control circuit is used to control the regulated current output according to the first control signal; A current output circuit, the current output circuit includes a control end and an input end, the input end of the current output circuit is connected to the output end of the output control circuit, and generates the output current of the transmitter according to a second control signal corresponding to the measurement signal received at the control end; The first control signal is a signal output by a power supply monitoring chip for monitoring the magnitude of the power supply output by the output end of the DC / DC module.

2. The circuit according to claim 1, wherein It further includes a power supply monitoring circuit, the input end of the power supply monitoring circuit is connected to the output end of the DC / DC module, and the output end of the power supply monitoring circuit is connected to the control end of the power supply control circuit and the control end of the output control circuit, and is used to control the power supply control circuit and the output control circuit to turn off when the power supply output by the DC / DC module is abnormal.

3. The circuit according to claim 1, wherein It further includes a control module, a V / I conversion circuit and a sampling circuit; The control signal output end of the control module is connected to the input end of the V / I conversion circuit, and the output end of the V / I conversion circuit is connected to the control end of the current output circuit; the V / I conversion circuit is used to convert a voltage signal into a current signal to output a second control signal to the current output circuit; The sampling circuit is connected between the current output circuit and a second wiring terminal, and the output end of the sampling circuit is connected to the control module, and is used to collect the output current; Wherein, the first wiring terminal is used as the positive power input, and the second wiring terminal is used as the negative power input.

4. The circuit according to claim 3, wherein, It further includes a reset latching circuit and an AND gate circuit; The reset latching circuit is connected to the reset end of the control module, and is used to detect the jump signal of the reset end of the control module and latch it as a fixed level; The first input end of the AND gate circuit is connected to the output end of the reset latching circuit, the second input end of the AND gate circuit is connected to the second control signal output end of the control module, and the output end of the AND gate circuit is connected to the control end of the power supply control circuit and the control end of the output control circuit.

5. The circuit according to any one of claims 1-4, characterized in that, The power supply current limiting circuit includes a first resistor, a second resistor, a voltage stabilizing diode and a first triode; The collector of the first triode is connected to the first terminal; the first end of the second resistor is connected to the first terminal; the second end of the second resistor is connected to the base of the first triode and the cathode of the voltage regulator diode; the reference signal terminal of the voltage regulator diode is connected to the emitter of the first triode and the first end of the first resistor; the anode of the voltage regulator diode and the second end of the first resistor are connected to the input end of the DC / DC module.

6. The circuit according to any one of claims 1-4, characterized in that, The power control circuit includes a third resistor, a fourth resistor, a fifth resistor, a second triode, and a first MOS transistor. The first and second poles of the first MOS transistor are respectively connected to the first and second ends of the power current limiting circuit. The first end of the third resistor is connected to the first pole of the first MOS transistor, and the second end of the third resistor is connected to the gate of the first MOS transistor; the first end of the fourth resistor is connected to the gate of the first MOS transistor, and the second end of the fourth resistor is connected to the collector of the second triode. The emitter of the second triode is grounded, and the base of the second triode is connected to the control terminal of the power control circuit; the first end of the fifth resistor is connected to the base of the second triode, and the second end of the fifth resistor is connected to the first terminal.

7. The circuit according to any one of claims 1-4, characterized in that, The output control circuit includes a sixth resistor, a seventh resistor, a third triode, and a second MOS transistor. The first end of the sixth resistor and the first pole of the second MOS transistor are connected to the first terminal. The second end of the sixth resistor is connected to the gate of the second MOS transistor. The second pole of the second MOS transistor is connected to the input end of the current output circuit; the first end of the seventh resistor is connected to the gate of the second MOS transistor, and the second end of the seventh resistor is connected to the collector of the third triode. The emitter of the third triode is grounded, and the base of the third triode is connected to the control terminal of the output control circuit.

8. The circuit according to any one of claims 1 to 4, characterized in that, The current output circuit includes a fourth triode and an eighth resistor. The base of the fourth triode is connected to the control terminal of the current output circuit. The collector of the fourth triode is connected to the output end of the output control circuit. The first end of the eighth resistor is connected to the emitter of the fourth triode and grounded, and the second end of the eighth resistor is connected to the output end of the current output circuit.

9. The circuit according to claim 3 or 4, characterized in that, The sampling circuit includes a ninth resistor. The first end of the ninth resistor is connected to the output end of the current output circuit, and the second end of the ninth resistor is connected to the second terminal.

10. A transmitter, characterized in that, An output diagnostic control circuit of the transmitter according to any one of claims 1-9 is included.

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