Relay switch control circuit and relay output type PLC controller

Abstract

The utility model provides a relay switch control circuit and a relay output type PLC controller, and the relay switch control circuit comprises a relay which comprises a coil, a first contact and a second contact, and the coil is used for controlling the opening and closing of the first contact and the second contact; the load loop power supply input terminal is connected with the first contact and is used for being connected with an external power supply through an external load; the load loop power supply common terminal is connected with the second contact and is used for being connected with an external power supply; the voltage division circuit is connected with the load loop power supply input terminal; the isolation circuit is connected with the load loop power supply common terminal; the feedback circuit is respectively connected with the voltage division circuit and the isolation circuit; the external power supply is an alternating current power supply, the first contact and the second contact are closed, and the signal output end of the feedback circuit outputs a first signal; the external power supply is an alternating current power supply, the first contact and the second contact are disconnected, and the signal output end outputs a second signal. According to the utility model, the reliability of AC control is improved.

Description

TECHNICAL FIELD

[0001] The utility model relates to relay control technical field, especially relay switch control circuit and relay output type PLC controller of relay. BACKGROUND

[0002] Relay is used for the control of load loop on-off, and big current operation is controlled through small current. But when relay controls load loop power-on, it is generally directly disconnected or on contact. When relay is used for AC loop control, arc phenomenon is easy to appear. Or in the case of open circuit in AC loop, closing relay may cause personnel to contact live part without knowing, increasing the risk of electric shock. Or misjudgment occurs that relay has been disconnected, while the actual relay is still in the closed state, thereby causing equipment damage, energy waste and electric shock of personnel and other serious consequences. SUMMARY

[0003] The utility model embodiment provides a relay switch control circuit and relay output type PLC controller to at least solve the above part technical problems existing in prior art.

[0004] In a first aspect, the utility model embodiment provides a relay switch control circuit, comprising:

[0005] A relay, the relay comprising a coil, a first contact and a second contact, the coil being used for controlling the disconnection and closure of the first contact and the second contact;

[0006] A load loop power input terminal connected with the first contact, the load loop power input terminal being further used for connecting with external power supply through external load;

[0007] A load loop power common terminal connected with the second contact, the load loop power common terminal being further used for connecting with external power supply;

[0008] A voltage division circuit connected with the load loop power input terminal;

[0009] An isolation circuit connected with the load loop power common terminal, used for isolating DC power supply;

[0010] A feedback circuit comprising a signal output end and two input ends, the two input ends being connected with the voltage division circuit and the isolation circuit respectively;

[0011] The external power supply is AC power supply, and the first contact and the second contact are closed, and the signal output end outputs a first signal;

[0012] The external power supply is an alternating current power supply, the first contact and the second contact are disconnected, the signal output end outputs a second signal, and the second signal is a pulse signal.

[0013] In an optional embodiment, the feedback circuit comprises:

[0014] The bidirectional photoelectric coupler comprises a light emitter and a light receiver, the light emitter has a first input end and a second input end, the first input end is connected to the voltage dividing circuit, the second input end is connected to the isolation circuit, and the collector of the light receiver is connected to a high level through a pull-up resistor to form the signal output end.

[0015] The external power supply is an alternating current power supply, the first contact and the second contact are disconnected, the signal output end outputs a second signal, and the second signal is a pulse signal.

[0016] The external power supply is an alternating current power supply, the first contact and the second contact are disconnected, the signal output end outputs a second signal, and the second signal is a pulse signal.

[0017] In an optional embodiment, the voltage dividing circuit comprises at least two resistors connected in series.

[0018] In an optional embodiment, the isolation circuit comprises a capacitor.

[0019] In an optional embodiment, the isolation circuit and the voltage dividing circuit form a resistance-capacitance absorption circuit for absorbing impact current generated when the relay is attracted and disconnected.

[0020] In a second aspect, the utility model embodiment provides a relay output type PLC controller, comprising:

[0021] A processing unit;

[0022] A plurality of power supply input ends, each power supply input end is connected to an external power supply through an external load;

[0023] A power supply common end connected to an external power supply;

[0024] A plurality of relay switch control circuits according to the utility model embodiments, wherein the signal output end is connected to the processing unit, each load circuit power input terminal is connected to a power supply input end, and the load circuit power common terminal is connected to the power supply common end.

[0025] The processing unit is configured to determine the zero-crossing point of the alternating current power supply according to the second signal and make the instruction for controlling the coil to be powered at the zero-crossing point.

[0026] In an optional embodiment, the processing unit is configured to, after issuing an instruction for controlling the coil to be powered off, if the signal output end outputs a first signal, issue a prompt information.

[0027] In an optional embodiment, the processing unit is configured to, if the first signal is output by the signal output end when the first contact and the second contact of the relay are disconnected, issue a prompt information.

[0028] An embodiment of the utility model has the following advantages or beneficial effects:

[0029] The relay switch control circuit of the embodiment of the utility model comprises: a relay, the relay comprises a coil, a first contact and a second contact, the coil is used for controlling the disconnection and closure of the first contact and the second contact; a load loop power input terminal connected with the first contact, the load loop power input terminal is also used for connecting with an external power supply through an external load; a load loop power common terminal connected with the second contact, the load loop power common terminal is also used for connecting with the external power supply; a voltage dividing circuit connected with the load loop power input terminal; an isolation circuit connected with the load loop power common terminal and used for isolating a direct current power supply; a feedback circuit comprising a signal output end and two input ends, the two input ends are connected with the voltage dividing circuit and the isolation circuit respectively; the external power supply is an alternating current power supply, and the first contact and the second contact are closed, the signal output end outputs a first signal; the external power supply is an alternating current power supply, and the first contact and the second contact are disconnected, the signal output end outputs a second signal, the second signal is a pulse signal. The feedback circuit can output different signals when the contacts of the relay are closed or disconnected, so that the actual situation of the alternating current loop can be fed back, so that the user can make a response according to the actual situation, and the problem caused by the direct control of the loop by the relay switch control circuit without a feedback mechanism is improved. BRIEF DESCRIPTION OF DRAWINGS

[0030] The above and other features and advantages of the utility model will become more apparent by describing in detail example embodiments thereof with reference to the attached drawings.

[0031] Figure 1 It is a structural schematic diagram of a relay switch control circuit according to an example embodiment;

[0032] Figure 2 It is an electric principle structural schematic diagram of a relay switch control circuit according to an example embodiment;

[0033] Figure 3 It is a principle schematic diagram of a relay output type PLC controller according to an example embodiment.

[0034] Wherein, the reference signs are explained as follows: 1-relay, 11-coil, 12-first contact, 13-second contact, 2-load loop power input terminal, 3-load loop power common terminal, 4-voltage dividing circuit, 5-isolation circuit, 6-feedback circuit, 61-signal output end, 62-light emitter, 63-light receiver, 64-pull-up resistor, 7-processing unit, 8-power input end, 9-power common, 200-external load, 300-external power supply. DETAILED DESCRIPTION

[0035] Example embodiments now will be described more fully hereinafter with reference to the accompanying drawings; however, the example embodiments can be implemented in many different forms and should not be construed as limited to the implementations set forth herein; rather, these implementations are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the example embodiments to those skilled in the art. Like reference numerals refer to like elements throughout the figures, and thus a detailed description of them will not be repeated.

[0036] The terms "a", "an", "the", "said", "at least one" are used to denote one or more elements / components / etc.; the terms "including" and "having" are used to mean that there are additions to the elements / components / etc. listed are also possible.

[0037] Referring to Figures 1 to 3 The relay 1 switching control circuit provided by the embodiment of the present application includes a relay 1, a load loop power input terminal 8, a load loop power common terminal 9, a voltage dividing circuit 4, an isolation circuit 5 and a feedback circuit 6. The relay 1 includes a coil 11, a first contact 12 and a second contact 13. The coil 11 is used to control the opening and closing of the first contact 12 and the second contact 13. The load loop power input terminal 8 is connected with the first contact 12. The load loop power input terminal 8 is also used to be connected with an external power supply 300 through an external load 200. The load loop power common terminal 9 is connected with the second contact 13. The load loop power common terminal 9 is also used to be connected with the external power supply 300. The voltage dividing circuit 4 is connected with the load loop power input terminal 8. The isolation circuit 5 is connected with the load loop power common terminal 9 and is used to isolate a direct current power supply. The feedback circuit 6 includes a signal output end 61 and two input ends. The two input ends are connected with the voltage dividing circuit 4 and the isolation circuit 5 respectively.

[0038] The external power supply 300 is an alternating current power supply. The first contact 12 and the second contact 13 are closed. The signal output end 61 outputs a first signal.

[0039] The external power supply 300 is an alternating current power supply. The first contact 12 and the second contact 13 are opened. The signal output end 61 outputs a second signal.

[0040] In the embodiment of the utility model, when the external power supply 300 is an alternating current power supply, if the first contact 12 and the second contact 13 are closed, the signal output end 61 of the feedback circuit 6 outputs a first signal, if the first contact 12 and the second contact 13 are disconnected, the signal output end 61 of the feedback circuit 6 outputs a second signal, according to different control states of the relay 1, the feedback circuit 6 outputs different signals, so that the actual situation of the alternating current loop can be fed back, so that the user can make response according to the actual situation, and the problem that the relay 1 switch control circuit has no feedback mechanism and directly controls the loop is improved.

[0041] In the exemplary embodiment, the second signal is a pulse signal. The pulse signal can realize detection of the zero crossing point of the alternating current power supply, and the first contact 12 and the second contact 13 can be closed based on the zero crossing point, so that the generation of sparks and arcs can be reduced.

[0042] In the relay 1 switch control circuit of the embodiment of the utility model, one end of the external power supply 300 is connected with the load loop power supply input end 8 sub 2 through the external load 200, the load loop power supply input end 8 sub 2 is divided into two paths, one path is connected with the first contact 12 of the relay 1, when the first contact 12 and the second contact 13 of the relay 1 are closed, it is connected to the load loop power supply common end 9 sub 3 through the second contact 13, the load loop power supply common end 9 sub 3 is directly connected with the other end of the external power supply 300 to form a load loop one, the other path is connected with the voltage dividing circuit 4, the voltage dividing circuit 4 is connected with one input end of the feedback circuit 6 through the photoelectric coupler U1, the other input end of the voltage dividing circuit 4 of the photoelectric coupler U1 is connected with the isolation circuit 5, the isolation circuit 5 is connected with the load loop power supply common end 9 sub 3, and the load loop power supply common end 9 sub 3 is connected to the other end of the power supply to constitute a load loop two.

[0043] The isolation circuit 5 is connected in series in the load loop two, can isolate the direct current power supply, so that the relay 1 switch control circuit of the embodiment of the utility model can be compatible with the control of the direct current load loop formed by introducing the external direct current power supply. The relay 1 switch control circuit of the embodiment of the utility model can be used for the control of the alternating current load loop and the control of the direct current load loop.

[0044] When the external power supply 300 is an alternating current power supply, the load loop power supply input end 8 sub 2 is connected with the live wire of the external alternating current power supply through the external load 200, and the load loop power supply common end 9 sub 3 is directly connected with the zero line of the external alternating current power supply. When the external power supply 300 is a direct current power supply, the load loop power supply input end 8 sub 2 is connected with the positive electrode of the external direct current power supply through the external load 200, and the load loop power supply common end 9 sub 3 is directly connected with the negative electrode of the external direct current power supply.

[0045] When the external power supply 300 is an AC power supply, when the first contact 12 and the second contact 13 of the relay 1 are disconnected, the load circuit one is not conductive, the load circuit two is conductive to the external AC power supply, and the feedback circuit 6 in the load circuit two outputs a second signal. When the first contact 12 and the second contact 13 of the relay 1 are closed, the load circuit one is conductive, the external AC power supply provides stable power supply for the external load 200 through the load circuit one, ensures the normal operation of the load, the load circuit two is not conductive, and the feedback circuit 6 in the load circuit two outputs a first signal. When the external power supply 300 is an AC power supply, the signals output by the feedback circuit 6 in different control states of the relay 1 are different, and the signals output by the feedback circuit 6 can be used to judge the control state of the relay 1.

[0046] In the example embodiment, when the feedback circuit 6 outputs the first signal, the control state of the relay 1 is that the first contact 12 and the second contact 13 are closed, the load circuit one is conductive, and the external AC power supply provides stable power supply for the external load 200 through the load circuit one. When the feedback circuit 6 outputs the second signal, the control state of the relay 1 is that the first contact 12 and the second contact 13 are disconnected, the load circuit one is not conductive, and the external AC power supply cannot provide power supply for the external load 200. If the signal output by the feedback circuit 6 does not correspond to the control state of the relay 1, it indicates that there may be a fault in the load circuit or the control circuit, and a warning can be issued to prompt the user to check.

[0047] In the example embodiment, when the coil 11 of the relay 1 is powered off, the contact opening operation is performed, the first contact 12 and the second contact 13 should be disconnected, the load circuit one is not conductive, and the load circuit two is conductive. At this time, the feedback circuit 6 should output the second signal. If the feedback circuit 6 outputs the first signal, there may be a situation that the first contact 12 and the second contact 13 are not correctly disconnected, and a warning can be issued to prompt the user to check, so as to avoid equipment damage, energy waste, and consequences such as electric shock of personnel.

[0048] Alternatively, in the case that the first contact 12 and the second contact 13 are disconnected, the load circuit one is not conductive, and the load circuit two is conductive. At this time, the feedback circuit 6 should output the second signal. If the feedback circuit 6 outputs the first signal, there may be an open circuit in the load circuit, and a warning can be issued to prompt the user to check, so as to avoid the risk of electric shock of personnel caused by performing the closing operation of the relay 1.

[0049] When the load circuit two is conducting, the external power supply 300 is an AC power supply, the input feedback circuit 6 is an AC voltage, and the second signal output by the feedback circuit 6 can be a pulse signal that is transformed with the positive and negative half waves of the AC power supply. According to the pulse signal, the zero-crossing point of the AC power supply can be obtained, the coil 11 of the relay 1 is controlled to be energized near the zero-crossing point, the first contact 12 and the second contact 13 are conducting, and the phenomenon that the relay 1 generates sparks and arcs when being closed can be improved. The pulse signal can also be used for time synchronization and timing functions.

[0050] When the external power supply 300 is a DC power supply, when the first contact 12 and the second contact 13 of the relay 1 are open, the load circuit one is not conducting, and the load circuit two has the isolation circuit 5 in series, so the load circuit two is isolated from the DC power supply. Therefore, the load circuit two is not conducting to the external DC power supply. When the first contact 12 and the second contact 13 of the relay 1 are closed, the load circuit one is conducting, and the load circuit two is not conducting. The external DC power supply provides stable power supply for the external load 200 through the load circuit one, and normal operation of the load is ensured.

[0051] One of the first contact 12 and the second contact 13 can be a moving contact, and the other can be a stationary contact. For example, the first contact 12 can be a moving contact, and the second contact 13 can be a stationary contact. When the coil 11 is energized, the first contact 12 and the second contact 13 are closed. When the coil 11 is de-energized, the first contact 12 and the second contact 13 are open.

[0052] In the embodiment of the utility model, the first signal can be a high level.

[0053] In some embodiments, referring to Figure 2 The feedback circuit 6 includes a photoelectric coupler U1, the photoelectric coupler U1 includes a light emitter 62 and a light receiver 63, two ends of the light emitter 62 are connected with the voltage dividing circuit 4 and the isolation circuit 5 respectively, a collector of the light receiver 63 is connected with a high level through a pull-up resistor 64, and a signal output end 61 is formed. When the load circuit two is not conducting, the collector of the light receiver 63 is connected with the high level through the pull-up resistor 64, and thus a high level is output. When the load circuit two is conducting, because the input voltage is an AC voltage, the zero-crossing point of the positive and negative half waves of the AC voltage that flows through the input end of the photoelectric coupler U1 can be obtained according to the conduction threshold of the photoelectric coupler U1. The AC voltage is not conducting when the positive and negative half waves are near the zero point, the photoelectric coupler U1 outputs a high level signal, the AC voltage is conducting when the positive and negative half waves are far from the zero point, the photoelectric coupler U1 outputs a low level signal, and thus a pulse signal is output at the signal output end 61 when the photoelectric coupler U1 has an AC current. The input and output are electrically isolated through optical coupling, and the influence of high voltage or noise on the downstream circuit is effectively prevented. In a specific implementation, the high level VCC to which the collector is connected through the pull-up resistor 64 can adopt a DC 3.3V power supply voltage. The pull-up resistor 64 can provide a default high level signal for the signal output end 61.

[0054] In some embodiments, referring to Figure 2 , the optocoupler U1 can be a bidirectional optocoupler U1. In exemplary embodiments, the feedback circuit 6 comprises the bidirectional optocoupler U1, the bidirectional optocoupler U1 comprises a light emitter 62 and a light receiver 63, the light emitter 62 has a first input end connected to the voltage dividing circuit 4 and a second input end connected to the isolation circuit 5, the collector of the light receiver 63 is connected to a high level through a pull-up resistor 64 to form a signal output end 61; when the external power supply 300 is an alternating current power supply and the first contact 12 and the second contact 13 are closed, the signal output end 61 outputs a high level; when the external power supply 300 is an alternating current power supply and the first contact 12 and the second contact 13 are open, the signal output end 61 outputs a pulse signal. Because the input voltage is an alternating voltage, the conduction threshold of the bidirectional optocoupler U1 can obtain the zero-crossing point of the positive and negative half-wave transformation of the alternating current flowing through its input end, the alternating current does not conduct when the positive and negative half-waves are close to zero, the bidirectional optocoupler U1 outputs a high level signal, and the bidirectional optocoupler U1 conducts when the positive and negative half-waves are far away from zero, the bidirectional optocoupler U1 outputs a low level signal, so when the bidirectional optocoupler U1 has an alternating current, a narrow pulse alternating zero-crossing signal waveform with a frequency twice that of the alternating current will be output at the signal output end 61. By detecting the signal output at the signal output end 61, functions such as alternating current zero-crossing detection, open circuit detection, and relay 1 control feedback can be realized. The narrow pulse zero-crossing signal waveform can be further used for time synchronization and timing functions, and can also be used for applications that control the conduction angle of the alternating current. The use of the bidirectional optocoupler U1 can improve the zero-crossing detection efficiency by 2 times, and better meet the needs of real-time control.

[0055] In some embodiments, referring to Figure 2 , the voltage dividing circuit 4 can be a resistor voltage dividing circuit 4 comprising resistors.

[0056] In exemplary embodiments, referring to Figure 2 , the voltage dividing circuit 4 comprises at least two resistors R1, R2 connected in series. Connecting two resistors of the same resistance value in series can avoid losing the protection of the subsequent circuit when one resistor fails, reduce the risk of complete circuit failure, and also disperse the heat generated by the same current flowing through the resistors, greatly improving the reliability and service life of the circuit. The resistance values of the two resistors R1 and R2 can be, for example, 60K.

[0057] In some embodiments, referring to Figure 2 , the isolation circuit 5 can be, for example, a capacitor isolation circuit 5. The capacitor isolation circuit 5 can isolate the direct current power supply. In exemplary embodiments, referring to Figure 2The isolation circuit 5 includes a capacitor Cl. The capacitor Cl can be a high-voltage ceramic capacitor, which can isolate the DC power supply, so that the relay 1 switching control circuit can be compatible with the DC load loop formed by introducing an external DC power supply, and increase the practicability of the circuit in various applications.

[0058] In some embodiments, referring to Figure 2 The isolation circuit 5 and the voltage dividing circuit 4 form a resistance-capacitance absorption circuit for absorbing the impact current generated when the relay 1 is attracted and disconnected. The capacitor in the isolation circuit and the resistor in the voltage dividing circuit 4 can form an RC resistance-capacitance absorption circuit, which can effectively absorb and weaken the impact current generated when the relay 1 is attracted and disconnected, and reduce the generation of sparks and arcs.

[0059] One end of the external power supply 300 is connected to the load loop power supply input end 8sub2 through the external load 200. The load loop power supply input end 8sub2 is divided into two paths. One path is connected to the first contact 12 of the relay 1. When the first contact 12 and the second contact 13 of the relay 1 are closed, it is connected to the load loop power supply common end 9sub3 through the second contact 13, and the load loop power supply common end 9sub3 is directly connected to the other end of the external power supply 300 to form a load loop one. The other path is connected to the resistor R1, the other end of the resistor R1 is connected to the resistor R2, the resistor R2 is connected to the first input end of the bidirectional optocoupler U1, the second input end of the bidirectional optocoupler U1 is connected to the capacitor Cl, and the capacitor Cl is connected to the second contact 13 of the relay 1, and then connected to the other end of the power supply through the load loop power supply common end 9sub3 to form a load loop two.

[0060] According to the external power supply 300, different load loops can be formed. When the external power supply 300 is an AC power supply, an AC load loop is formed. When the external power supply 300 is a DC power supply, a DC load loop is formed.

[0061] When the first contact 12 and the second contact 13 of the relay 1 are disconnected, any external power supply 300, load circuit one is not conductive, load circuit two is conductive to the external AC power supply, and is not conductive to the external DC power supply. The external AC power supply is divided by R1 and R2 to provide an appropriate input voltage for the opto-coupler U1. Since the input voltage is an AC voltage, the zero-crossing point of the positive and negative half-wave of the AC current flowing through the input of the opto-coupler U1 can be obtained by matching the conduction threshold of the opto-coupler U1. The AC current is not conductive when the positive and negative half-wave is close to zero, and the opto-coupler U1 outputs a high-level signal. When the positive and negative half-wave is far from zero, the opto-coupler U1 outputs a low-level signal. Therefore, when the opto-coupler U1 has an AC current, a narrow pulse AC zero-crossing signal waveform with a frequency twice that of the AC current will be output at the signal output end 61. The AC zero-crossing detection, open circuit detection, and relay 1 control feedback functions can be realized by detecting this pulse signal. The narrow pulse zero-crossing signal waveform can be further used for time synchronization and timing functions, and can also be used for applications that control the conduction angle of the AC current.

[0062] When the first contact 12 and the second contact 13 of the relay 1 are closed, load circuit one is conductive, load circuit two is not conductive, and the external power supply 300 provides stable power supply for the external load 200 through load circuit one, ensuring normal operation of the load.

[0063] By controlling the closing and conduction of the relay 1 near the AC zero-crossing point, i.e. between the rising edge and the falling edge of the AC zero-crossing signal waveform, the arc phenomenon that occurs when the relay 1 controls a high-power load or an inductive load can be effectively suppressed. In addition, the RC resistance-capacitance absorption circuit composed of resistors R1 and R2 and capacitor C1 in the circuit can fully absorb the large current that occurs when the relay 1 is disconnected and closed, thereby improving the spark and arc problems that occur when the relay 1 is controlled.

[0064] When the relay 1 is disconnected, load circuit two is conductive to the external AC power supply, and the signal output end 61 will generate a narrow pulse AC zero-crossing signal waveform. When the load circuit is open, the signal output end 61 will maintain a high level. By detecting the level signal state of the signal output end 61 before the relay 1 is closed, it can be determined whether the load circuit has an open circuit.

[0065] When the control relay 1 is disconnected, the actual relay 1 is disconnected, and the load circuit two is conductive to the external AC power supply. At this time, the signal output end 61 will generate a narrow pulse AC zero-crossing signal waveform. If the actual relay 1 is still in the closed state, the load circuit two is not conductive, and the signal output end 61 outputs a continuous high-level signal. By detecting the signal state output by the feedback circuit 6, the real-time feedback of the relay 1 control can be obtained.

[0066] Referring toFigure 3 The utility model embodiment provides a relay 1 output type PLC controller, including processing unit 7, a plurality of power input 8, a power common end 9 and at least one relay 1 switch control circuit of the utility model embodiment, through setting a plurality of relay 1 switch control circuit, the relay 1 output type PLC controller of the utility model embodiment can realize the control of multiple load loop.

[0067] Each power input 8 in a plurality of power inputs 8 is connected with external power supply 300 through external load 200, power common end 9 is connected with external power supply 300, signal output end 61 in the relay 1 switch control circuit of the utility model embodiment is connected with processing unit 7, each load loop power input 8 sub 2 is connected with one power input 8, and load loop power common end 9 sub 3 of all relay 1 switch control circuit is connected with power common end 9.

[0068] Processing unit 7 is configured to determine the zero-crossing point of the alternating current power supply according to the second signal, and to issue a command to energize the control coil 11 at the zero-crossing point.

[0069] In some embodiments, processing unit 7 is configured to issue a prompt message if signal output end 61 outputs a first signal after issuing a command to de-energize control coil 11. At this time, there may be a situation where first contact 12 and second contact 13 are not properly disconnected, and the user can check according to the prompt message to avoid equipment damage, energy waste, and the consequences of electric shock.

[0070] In some embodiments, processing unit 7 is configured to issue a prompt message if signal output end 61 outputs a first signal in the event that first contact 12 and second contact 13 of relay 1 are disconnected. At this time, there may be a situation where the load loop is open, and the user can check according to the prompt message to avoid the risk of electric shock caused by performing relay 1 closing operation.

[0071] In the utility model embodiment, processing unit 7 is mainly used to receive and process control instructions from the host computer software, send PLC operation and alarm status, execute control logic, detect output signals of relay 1 switch control circuit, determine whether there is an AC zero-crossing point, whether there is an open circuit in the AC loop, and whether relay 1 is completely disconnected. Processing unit 7 is also used to output control signals to control whether relay 1 coil 11 in relay 1 switch control circuit is energized, and further control whether relay 1 is open or closed.

[0072] The relay 1 output type PLC controller of the utility model embodiment has a plurality of power inputs 8, for example Figure 3The eight power input terminals 8 shown in the figure are connected to one end of the external power source 300 through the external load 200, and the power common terminal 9 is connected to the other end of the external power source 300. Figure 3 The relay 1 output type PLC controller shown in the figure can realize an 8-port output control module, and can control the working state of up to 8 loads.

[0073] The external power source 300 can be a direct current power source or an alternating current power source. When the direct current power source is used, the positive electrode of the power source is connected to the power input terminal 8 through the external load 200, and the negative electrode of the direct current power source is directly connected to the power common terminal 9. When the alternating current power source is used, the live wire of the power source is connected to the load and then connected to the power input terminal 8, and the zero line of the power source is directly connected to the power common terminal 9.

[0074] The external load 200 is connected to a direct current load when the external power source 300 is a direct current power source, and is connected to an alternating current load when the external power source 300 is an alternating current power source.

[0075] The working process of the relay 1 output type PLC controller in the embodiment of the utility model is as follows:

[0076] When the PLC controller is powered on and works, the external load 200 and the external power source 300 are also connected. When the alternating current load and the alternating current external power source 300 are connected, and the first contact 12 and the second contact 13 of the relay 1 are disconnected, the signal output end 61 of the relay 1 switch control circuit is connected to the processing unit 7, and the processing unit 7 can determine whether the alternating current loop is open by detecting the level signal output by the signal output end 61, and can also detect the alternating current zero-crossing point signal. When the relay 1 in the relay 1 switch control circuit is closed at the alternating current zero-crossing point, the influence of the load power-on transient current can be effectively suppressed. After the relay 1 in the relay 1 switch control circuit is closed, the signal output by the signal output end 61 is in a high level state. If the processing unit 7 sends a relay 1 disconnection signal at this time, the signal state output by the signal output end 61 of the relay 1 switch control circuit can be detected to determine whether the relay 1 is correctly disconnected. When the relay 1 is correctly disconnected, the signal output by the signal output end 61 is a narrow pulse signal waveform. Through the relay 1 switch control circuit, the safe and stable operation of the PLC controller and the load can be effectively guaranteed, and the service life of the module and the equipment can be improved.

[0077] In the embodiment of the utility model, the term "a plurality of" refers to two or more, unless otherwise explicitly limited. The terms "mounting", "connecting", "fixing" and the like should be understood in a broad sense, for example, "connecting" can be fixed connection, or detachable connection, or integral connection. For those skilled in the art, the specific meaning of the above terms in the embodiment of the utility model can be understood according to the specific circumstances.

[0078] In the description of the embodiments of the present application, it should be understood that the terms "upper", "lower" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the embodiments of the present application and simplify the description, and do not indicate or imply that the device or unit referred to must have a particular direction, be constructed and operated in a particular orientation, therefore, it should not be understood as a limitation on the embodiments of the present application.

[0079] In the description of the present application, the terms "one embodiment", "one preferred embodiment" and the like mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In the present application, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0080] The above is only the preferred embodiment of the present application, and is not intended to limit the embodiments of the present application. For those skilled in the art, the embodiments of the present application can be variously changed and modified. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the embodiments of the present application should be included in the protection scope of the embodiments of the present application.

Claims

1. A relay switch control circuit, characterized in that, include: A relay, comprising a coil, a first contact, and a second contact, wherein the coil is used to control the opening and closing of the first contact and the second contact; A load circuit power input terminal is connected to the first contact, and the load circuit power input terminal is also used to connect to an external power source through an external load. A common power supply terminal for the load circuit is connected to the second contact, and the common power supply terminal for the load circuit is also used to connect to an external power source. The voltage divider circuit is connected to the power input terminal of the load circuit. An isolation circuit is connected to the common terminal of the load circuit power supply to isolate DC power. The feedback circuit includes a signal output terminal and two input terminals, the two input terminals being respectively connected to the voltage divider circuit and the isolation circuit; The external power supply is AC power, and the first contact and the second contact are closed, and the signal output terminal outputs the first signal; The external power supply is AC power, and the first contact and the second contact are disconnected. The signal output terminal outputs a second signal, which is a pulse signal.

2. The relay switch control circuit according to claim 1, characterized in that, The feedback circuit includes: A bidirectional optocoupler includes a emitter and a receiver. The emitter has a first input terminal and a second input terminal. The first input terminal is connected to the voltage divider circuit, and the second input terminal is connected to the isolation circuit. The collector of the receiver is connected to a high level through a pull-up resistor to form the signal output terminal. The external power supply is AC power, and the first contact and the second contact are closed, and the signal output terminal outputs a high level; The external power supply is AC power, and the first contact and the second contact are disconnected, and the signal output terminal outputs a pulse signal.

3. The relay switch control circuit according to claim 2, characterized in that, The voltage divider circuit includes at least two resistors connected in series.

4. The relay switch control circuit according to claim 3, characterized in that, The isolation circuit includes a capacitor.

5. The relay switch control circuit according to claim 4, characterized in that, The isolation circuit and the voltage divider circuit form a resistor-capacitor absorption circuit, which is used to absorb the inrush current generated when the relay is turned on and off.

6. A relay output type PLC controller, characterized in that, include: Processing unit; Multiple power input terminals, each of which is connected to an external power source via an external load; One common power terminal connects to an external power source; The relay switch control circuit according to any one of claims 1-5, wherein the signal output terminal is connected to the processing unit, each load circuit power input terminal is connected to a power input terminal, and the load circuit power common terminal is connected to the power common terminal. The processing unit is configured to determine the zero-crossing point of the AC power supply based on the second signal, and to issue a command to energize the coil at the zero-crossing point.

7. The relay output type PLC controller according to claim 6, characterized in that, The processing unit is configured to issue a prompt message if the signal output terminal outputs a first signal after issuing a command to control the coil to be de-energized.

8. The relay output type PLC controller according to claim 6, characterized in that, The processing unit is configured to issue a prompt message if the signal output terminal outputs the first signal when the first contact and the second contact of the relay are disconnected.

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