Low voltage jog detection circuit for digital output devices

Abstract

The utility model provides a kind of low voltage jolt detection circuit of digital output equipment, the connection mode of the circuit includes: the DO channel of the circuit is connected with at least first loop and second loop;The first loop at least has MOS tube K1, the MOS tube K1 is connected with load;The second loop at least has MOS tube K2 and operational amplifier U1, the MOS tube K2 is connected with the operational amplifier U1, the MOS tube K2 is connected with the load, the circuit involved in the utility model can be low cost and efficiently realize the detection of load circuit short-circuit condition, while it can also avoid relay or other load misoperation.

Description

Technical Field

[0001] This utility model relates to a low-voltage jog detection circuit for a digital output device, and the technical field it relates to is industrial control. Background Technology

[0002] In a PLC control system, the digital output device (DO) module outputs 24V and 0V voltages. During the output process, the load status, such as short circuit or open circuit, provides crucial feedback information for the control system and is an important indicator of its health. When the DO channel outputs a high level of 24V, a short circuit in the load can be detected simply by checking if the feedback output signal is high; this detection will not cause malfunctions in the load. However, when outputting a low level of 0V, the load voltage is normally around 0V, and it is also 0V when the load is short-circuited. Therefore, whether the load is short-circuited cannot be directly determined by the feedback circuit.

[0003] In existing technologies, a short-circuit detection method is generally used, which involves outputting a brief high-level pulse and then checking whether a high level is detected across the load terminals to determine if a short circuit has occurred. For example, a DO output self-test circuit for a hydraulic RTU is disclosed on the Chinese patent website, with application number 201922363852.8. This method of detecting short-circuit loads by outputting brief high-level pulses may cause relay malfunctions or other malfunctions of controlled objects in certain precision control scenarios, which is extremely serious and unacceptable in many situations. Utility Model Content

[0004] The purpose of this invention is to enable the detection of load short circuits when the digital output is at a low level, without causing relays or other controlled objects to malfunction, thereby improving the stability of system control.

[0005] To achieve the above objectives, this utility model provides a low-voltage jog detection circuit for a digital output device. 1. The circuit is connected in the following manner: the DO channel of the circuit is connected to at least a first circuit and a second circuit; the first circuit has at least a MOS transistor K1, which is connected to the load; the second circuit has at least a MOS transistor K2 and an operational amplifier U1, which is connected to the operational amplifier U1 and the load.

[0006] Preferably, the circuit is connected in the following manner: the DO channel is connected to the first end of the MOS transistor K1, and the second ends of both the MOS transistor K1 and the MOS transistor K2 are connected to the load.

[0007] Preferably, the circuit is connected in such a way that the second circuit has at least a Zener diode, and pin 2 of the operational amplifier U1 is connected to the first end of the Zener diode.

[0008] Preferably, the circuit is connected in such a way that the second circuit has at least a resistor R1, and the second end of the resistor R1 is connected to the first end of the Zener diode.

[0009] Preferably, the circuit is connected in the following manner: the operational amplifier U1 is connected to the optocoupler U2, and pin 1 of the operational amplifier U1 is connected to pin 1 of the optocoupler U2.

[0010] Preferably, the circuit is connected in such a way that pin 4 of the optocoupler U2 is connected to the MCU circuit.

[0011] Preferably, the circuit is connected in such a way that both pin 2 and pin 3 of the optocoupler U2 are grounded.

[0012] Preferably, the circuit is connected in such a way that pin 3 of the operational amplifier U1 is connected to the DO channel.

[0013] The beneficial effect of this utility model is that it can realize the detection of short circuit conditions in the load circuit at low cost and high efficiency, while avoiding malfunction of relays or other loads. Attached Figure Description

[0014] Figure 1 This is a connection diagram of the circuit involved in this utility model.

[0015] Figure 2 This is a schematic diagram of the working principle of the circuit involved in this utility model. Detailed Implementation

[0016] It should be noted that when an electronic component has connection points in both the upper and lower directions, the upper end is referred to as the first end and the lower end as the second end.

[0017] Example 1: This example discloses a circuit connection method related to this utility model. See details below. Figure 1 .

[0018] In this embodiment, the circuit connection method is as follows.

[0019] The DO channel is connected to the first circuit and the second circuit.

[0020] The first circuit includes: MOSFET K1. The first terminal of MOSFET K1 is connected to the DO channel, and the second terminal of MOSFET K2 is connected to the load.

[0021] The second circuit includes: resistor R1, operational amplifier U1, Zener diode, and MOSFET K2. Pin 3 of operational amplifier U1 and the first terminal of resistor R1 are both connected to the DO channel. The second terminal of resistor R1 and pin 2 of operational amplifier U1 are both connected to the first terminal of the Zener diode. Resistor R1 and operational amplifier U1 are connected in parallel between the DO channel and the second terminal of the Zener diode. The second terminal of the Zener diode is connected to the first terminal of MOSFET K2, and the second terminal of MOSFET K2 is connected to the load.

[0022] This dual-loop system achieves interlocking functionality through level control: When the DO channel outputs a high level, the MOSFET K1 in the first loop is fully turned on due to sufficient gate drive voltage. Simultaneously, the operational amplifier U1 in the second loop outputs a saturated high level because its non-inverting input potential is higher than its inverting input, causing the optocoupler U2 to enter the cutoff state, thus putting the MOSFET K2 in the off mode. When the DO outputs a low level, K1 in the first loop is turned off due to gate undervoltage. At this time, the comparator function of the operational amplifier U1 turns on the second loop, transmitting the status signal to the MCU through opto-isolation.

[0023] Pin 1 of operational amplifier U1 is connected to pin 1 of optocoupler U2, and pin 4 of optocoupler U2 is connected to the MCU circuit.

[0024] Both pin 2 and pin 3 of the optocoupler U2 are grounded.

[0025] With the circuit connection described above, when the DO channel outputs a high level, the first circuit is turned on and the second circuit is turned off; when the DO channel outputs a low level, the second circuit is turned on and the first circuit is turned off, thus ensuring that jogging is only performed when the DO channel outputs a low level, ensuring that relays or other loads will not be triggered malfunctions.

[0026] Example 2: This example discloses the working process of a circuit related to this utility model. See details below. Figure 2 .

[0027] When the digital output channel is in a high-level output state, the circuit forms a specific conduction path. At this time, the first current loop is fully activated and conducts, while the second detection loop is electrically isolated. The specific current transmission path is as follows: starting from the DO channel output port, flowing through MOSFET K1, and finally reaching the load terminal to form a complete loop. It should be noted that in this operating mode, the system does not have real-time jogging detection function and cannot effectively monitor potential short-circuit faults at the load end.

[0028] When the DO channel switches to a low-level output state, the circuit topology undergoes a structural change. At this time, the first power loop is reliably shut off, and the second detection loop enters the working state. The current conduction path is reconstructed as follows: starting from the DO channel, it flows sequentially through the precision sampling resistor R1, the reference unit composed of the Zener diode, the controlled channel of the detection MOSFET K2, and finally reaches the load terminal.

[0029] In this configuration, when the system performs periodic jogging operations (such as the DO channel intermittently outputting a 24V pulse voltage), the circuit enters the load condition diagnostic mode.

[0030] If the load impedance exceeds the 150-ohm threshold, the differential voltage across the sampling resistor R1 will be lower than the 2.057V reference value. After processing by the precision amplification circuit composed of operational amplifier U1, the output voltage of this analog signal is strictly limited to below the 3.3V threshold. This voltage level is insufficient to trigger the conduction threshold (3.3V) of the optocoupler U2, causing the optocoupler to remain in the off state, thereby keeping the I / O port of the MCU circuit low-level signal output.

[0031] This electrical status indicates that the load circuit impedance is within the normal range and no short-circuit fault has occurred.

[0032] When the system detects that the load impedance is below the critical value of 150 ohms in low-level jogging mode, the circuit will trigger the abnormal state response mechanism.

[0033] At this point, the voltage difference across sampling resistor R1 exceeds the design value of 2.057V. After being amplified by operational amplifier U1, the output voltage jumps to over 3.3V. This voltage value reaches the precise conduction threshold of optocoupler U2, causing the optocoupler to enter a saturated conduction state. The conduction effect of the optocoupler's secondary winding pulls the potential of the corresponding I / O port of the MCU to a logic high level. This signal change is captured and interpreted by the microcontroller in real time as a load short-circuit alarm signal.

[0034] When the MCU circuit's I / O output is high, it indicates that there is an abnormality in the load state, and a short circuit has occurred.

[0035] It should also be noted that in the optocoupler U2, the electronic components include a light-emitting diode (LED) and a photosensitive element. When the output voltage of the operational amplifier U1 is less than 3.3V, the light generated by the LED is insufficient to cause the photosensitive element to generate current, or the current generated by the photosensitive element is low, resulting in a low level I / O output of the MCU circuit. When the output voltage of the operational amplifier U2 is greater than 3.3V, the light generated by the LED can cause the photoresistor to generate current, resulting in a high level I / O output of the MCU circuit.

[0036] Example 3: This example discloses the working process of a circuit related to this utility model. See details below. Figure 2 .

[0037] In this embodiment, the resistance value of resistor R1 is 150 ohms. When the resistance value of the load is less than 150 ohms, the channel is considered short-circuited. The conduction voltage of the optocoupler is 3.6V, the amplification factor of operational amplifier U1 is 2, and the operating voltage of Zener diode is 20.4V.

[0038] When the DO channel is in a high-level output state, the circuit forms a specific conduction path. At this time, the first current loop is fully activated and conducts, while the second detection loop is in an electrically isolated state. The specific current transmission path is as follows: starting from the DO channel output port, flowing through MOSFET K1, and finally reaching the load terminal to form a complete loop.

[0039] It should be noted that in this operating mode, the system does not have real-time jog detection function and cannot effectively monitor potential short-circuit faults at the load end.

[0040] When the DO channel switches to a low-level output state, the circuit's conduction path undergoes a structural change. At this time, the first power loop is reliably shut off, and the second detection loop enters the working state. The current conduction path is reconstructed as follows: starting from the DO channel, it flows sequentially through resistor R1, the reference unit composed of the Zener diode, the controlled channel of the detection MOSFET K2, and finally reaches the load terminal.

[0041] When the DO channel outputs a low level for jogging, such as when the DO channel periodically and briefly outputs a 24V voltage, if the load resistance is greater than 150 ohms, the current flowing through resistor R1 is less than 12mA. Therefore, the voltage difference across resistor R1 is less than 1.8V. The voltage across resistor R1 is amplified by operational amplifier U1 and the output voltage is less than 3.6V. At this time, since the voltage difference across optocoupler U2 is less than 3.6V, the conduction voltage has not been reached. Therefore, optocoupler U2 is not conducting, and the MCU circuit's IO output is low.

[0042] When the MCU circuit's I / O output is low, it indicates that the load is in normal condition and there is no short circuit.

[0043] When the DO channel outputs a low level for jogging, such as when the DO channel periodically and briefly outputs a 24V voltage, if the load resistance is less than 150 ohms, the current flowing through resistor R1 is greater than 12mA. Therefore, the voltage difference across resistor R1 is greater than 1.8V. The voltage across resistor R1 is amplified by operational amplifier U1 and the output voltage is greater than 3.6V. At this time, since the voltage difference across optocoupler U2 is greater than 3.6V, the conduction voltage is reached. Therefore, optocoupler U2 is turned on, and the MCU current IO output is high.

[0044] When the MCU current I / O output is high, it indicates that the load is in an abnormal state and a short circuit has occurred.

[0045] Example 4: This example discloses a working process of the present invention involving electric current. See details below. Figure 2 .

[0046] In this embodiment, the resistance value of resistor R1 is 100 ohms. When the resistance value of the load is less than 150 ohms, the channel is considered short-circuited. The conduction voltage of the optocoupler is 4.32V, the amplification factor of operational amplifier U1 is 3, and the operating voltage of Zener diode is 20.4V.

[0047] When the DO channel is in a high-level output state, the circuit forms a specific conduction path. At this time, the first current loop is fully activated and conducts, while the second detection loop is in an electrically isolated state. The specific current transmission path is as follows: starting from the DO channel output port, flowing through MOSFET K1, and finally reaching the load terminal to form a complete loop.

[0048] When the DO channel switches to a low-level output state, the circuit's conduction path undergoes a structural change. At this time, the first power loop is reliably shut off, and the second detection loop enters the working state. The current conduction path is reconstructed as follows: starting from the DO channel, it flows sequentially through resistor R1, the reference unit composed of the Zener diode, the controlled channel of the detection MOSFET K2, and finally reaches the load terminal.

[0049] When the DO channel outputs a low level for jogging, such as when the DO channel periodically and briefly outputs a 24V voltage, if the load resistance is greater than 150 ohms, the current flowing through resistor R1 is less than 14.4mA. Therefore, the voltage difference across resistor R1 is less than 1.44V. The voltage across resistor R1 is amplified by operational amplifier U1 and the output voltage is less than 4.32V. At this time, since the voltage difference across optocoupler U2 is less than 4.32V, the conduction voltage has not been reached. Therefore, optocoupler U2 is not conducting, and the MCU circuit's IO output is low.

[0050] When the MCU circuit's I / O output is low, it indicates that the load is in normal condition and there is no short circuit.

[0051] When the DO channel outputs a low level for jogging, such as when the DO channel periodically and briefly outputs a 24V voltage, if the load resistance is less than 150 ohms, the current flowing through resistor R1 is greater than 14.4mA. Therefore, the voltage difference across resistor R1 is greater than 1.44V. The voltage across resistor R1 is amplified by operational amplifier U1 and the output voltage is greater than 4.32V. At this time, since the voltage difference across optocoupler U2 is greater than 4.32V, the conduction voltage is reached. Therefore, optocoupler U2 is turned on, and the MCU current IO output is high.

[0052] When the MCU circuit's I / O output is high, it indicates that the load is in an abnormal state and a short circuit has occurred.

[0053] Example 5: This example discloses a connection method for the circuit involved in this utility model.

[0054] In this embodiment, the circuit connection method is as follows.

[0055] The DO channel is connected to the first circuit and the second circuit.

[0056] The first circuit includes: MOSFET K1. The first terminal of MOSFET K1 is connected to the DO channel, and the second terminal of MOSFET K2 is connected to the load.

[0057] The second circuit includes: resistor R1, operational amplifier U1, Zener diode, and MOSFET K2. Pin 3 of operational amplifier U1 and the first terminal of resistor R1 are both connected to the DO channel. The second terminal of resistor R1 and pin 2 of operational amplifier U1 are both connected to the first terminal of the Zener diode. Resistor R1 and operational amplifier U1 are connected in parallel between the DO channel and the second terminal of the Zener diode. The second terminal of the Zener diode is connected to the first terminal of MOSFET K2, and the second terminal of MOSFET K2 is connected to the load.

[0058] Pin 1 of operational amplifier U1 is connected to a relay, and the relay is connected to the MCU circuit.

[0059] Example 6 discloses the working process of the circuit involved in Example 5, based on Example 5.

[0060] In this embodiment, the resistance of resistor R1 is 200 ohms. When the resistance of the load is less than 200 ohms, the channel is considered short-circuited. The relay's on-state voltage is 4.4V, the operational amplifier U1's amplification factor is 2.2, and the Zener diode's operating voltage is 20V.

[0061] When the DO channel is in a high-level output state, the circuit forms a specific conduction path. At this time, the first current loop is fully activated and conducts, while the second detection loop is in an electrically isolated state. The specific current transmission path is as follows: starting from the DO channel output port, flowing through MOSFET K1, and finally reaching the load terminal to form a complete loop.

[0062] When the DO channel switches to a low-level output state, the circuit's conduction path undergoes a structural change. At this time, the first power loop is reliably shut off, and the second detection loop enters the working state. The current conduction path is reconstructed as follows: starting from the DO channel, it flows sequentially through resistor R1, the reference unit composed of the Zener diode, the controlled channel of the detection MOSFET K2, and finally reaches the load terminal.

[0063] When the DO channel outputs a low level for jogging, such as when the DO channel periodically and briefly outputs a 24V voltage, if the load resistance is greater than 200 ohms, the current flowing through resistor R1 is less than 10mA. Therefore, the voltage difference across resistor R1 is less than 2V. The voltage across resistor R1 is amplified by operational amplifier U1 and the output voltage is less than 4.4V. At this time, since the voltage difference across optocoupler U2 is less than 4.4V, the conduction voltage has not been reached. Therefore, optocoupler U2 is not conducting, and the MCU circuit's IO output is low.

[0064] When the MCU circuit's I / O output is low, it indicates that the load is in normal condition and there is no short circuit.

[0065] When the DO channel outputs a low level for jogging, such as when the DO channel periodically and briefly outputs a 24V voltage, if the load resistance is less than 200 ohms, the current flowing through resistor R1 is greater than 10mA. Therefore, the voltage difference across resistor R1 is greater than 2V. The voltage across resistor R1 is amplified by operational amplifier U1 and the output voltage is greater than 4.32V. At this time, since the voltage difference across optocoupler U2 is greater than 4.4V, the conduction voltage is reached. Therefore, optocoupler U2 is turned on, and the MCU current IO output is high.

[0066] When the MCU circuit's I / O output is high, it indicates that the load is in an abnormal state and a short circuit has occurred.

[0067] This utility model illustrates its purpose, technical solution, and beneficial effects through specific embodiments. However, these embodiments are merely examples to demonstrate the application of the invention and do not constitute a limitation on the scope of protection of this utility model. We explicitly state that any reasonable modifications, equivalent substitutions, or technical improvements guided by the spirit and principles of this utility model should be included within its scope of protection. This means that as long as these changes do not deviate from the core idea and basic function of the invention, they should be protected by patent rights. The scope of protection of this utility model should be broad, including all directly obvious variations as well as non-obvious innovations that a technical expert can reasonably deduce from the disclosure of this utility model. This broad protection aims to promote further research and development based on this utility model, while ensuring that its innovativeness and practicality receive comprehensive legal protection.

Claims

1. A low voltage jog detection circuit for a digital output device, characterized by, The circuit connection methods include: The DO channel of the circuit is connected to at least the first circuit and the second circuit; The first circuit has at least one MOSFET K1, which is connected to the load; The second circuit has at least a MOSFET K2 and an operational amplifier U1, wherein the MOSFET K2 is connected to the operational amplifier U1 and the load is connected to the load.

2. A low voltage jog detection circuit for a digital output device according to claim 1, wherein, The circuit connection methods include: The DO channel is connected to the first end of the MOS transistor K1, and the second ends of both the MOS transistor K1 and the MOS transistor K2 are connected to the load.

3. The low-voltage jog detection circuit for a digital output device according to claim 1, characterized in that, The circuit connection methods include: The second circuit has at least a Zener diode, and pin 2 of the operational amplifier U1 is connected to the first end of the Zener diode.

4. The low-voltage jog detection circuit for a digital output device according to claim 3, characterized in that, The circuit connection methods include: The second circuit has at least a resistor R1, and the second end of the resistor R1 is connected to the first end of the Zener diode.

5. The low-voltage jog detection circuit for a digital output device according to claim 1, characterized in that, The circuit connection methods include: The operational amplifier U1 is connected to the optocoupler U2, and pin 1 of the operational amplifier U1 is connected to pin 1 of the optocoupler U2.

6. The low-voltage jog detection circuit for a digital output device according to claim 5, characterized in that, The circuit connection methods include: Pin 4 of the optocoupler U2 is connected to the MCU circuit.

7. A low-voltage jog detection circuit for a digital output device according to claim 5 or 6, characterized in that, The circuit connection methods include: Both pin 2 and pin 3 of the optocoupler U2 are grounded.

8. A low-voltage jog detection circuit for a digital output device according to any one of claims 1 to 6, characterized in that, The circuit connection methods include: Pin 3 of the operational amplifier U1 is connected to the DO channel.

Images