I / O expansion circuit board for PLC

Abstract

An I / O expansion circuit board for a PLC comprises a PCB, the PCB is provided with a front-end signal terminal, a front-end signal shaping unit, a signal amplitude adjusting unit, an input signal indicating unit, a relay array unit, a signal anti-channeling circuit and an eight-bit output port, the upper end of the front-end signal shaping unit is connected with the front-end signal terminal, and the lower end of the front-end signal shaping unit is connected with the signal amplitude adjusting unit; the upper end of the relay array unit is connected with the input signal indication unit, and the lower end is connected with the signal anti-channeling circuit; the signal amplitude adjusting unit is connected with the relay array unit through the input signal indicating unit; according to the utility model, the number of expanded I / O ports is large, the cost is low, the circuit is simple, and a plurality of PLC hosts do not need to be used at the same time.

Description

Technical Field

[0001] The utility model relates to the technical field of PLC control, in particular to an I / O expansion circuit board for PLC. Background Art

[0002] In PLC automation control, the PLC host's I / O ports are fixed and limited. To increase the number of I / O ports, dedicated I / O expansion modules must be purchased. Furthermore, the number of I / O expansion modules available for a PLC host is also very limited. When a PLC host is fully populated with I / O expansion modules, but the I / O count still falls short of project requirements, it's necessary to consider connecting multiple PLC hosts in parallel. This significantly increases the cost of building the system and complicates the wiring between ports. These shortcomings are particularly pronounced for projects with up to a thousand I / O ports. Summary of the Invention

[0003] To address the problems of increased costs, complex parallel wiring, and impracticality for projects with thousands of I / O ports caused by the need to use dedicated I / O expansion modules for expansion due to the insufficient number of I / O ports in existing PLC hosts, the present invention provides an I / O expansion circuit board for PLCs. This board aims to address the technical defects caused by the fixed number of I / O ports in existing PLCs. It features a large number of I / O port expansions, low cost, easy expansion, simple wiring, and does not require the use of multiple PLC hosts. This is achieved through the following technical solutions:

[0004] A PLC I / O expansion circuit board comprises a PCB board, wherein the PCB board is designed with a front-end signal terminal, a front-end signal shaping unit, a signal amplitude adjustment unit, an input signal indication unit, a relay array unit, an anti-signal backflow circuit, and an 8-bit output port. The upper end of the front-end signal shaping unit is connected to the front-end signal terminal, and the lower end is connected to the signal amplitude adjustment unit; the upper end of the relay array unit is connected to the input signal indication unit, and the lower end is connected to the anti-signal backflow circuit; the signal amplitude adjustment unit is connected to the relay array unit via the input signal indication unit; and the lower end of the anti-signal backflow circuit is connected to the 8-bit output port.

[0005] Preferably, the front-end signal terminal is designed with port 1, port 2, ..., port 9, the ports 1 to 8 are used to connect to external device terminals, and the port 9 is used to connect to a power ground wire.

[0006] Preferably, eight groups of front-end signal shaping circuits are designed in the front-end signal shaping unit, and the front-end signal shaping circuits are connected to eight adjacent ports in the front-end signal terminal.

[0007] Preferably, the signal amplitude adjustment unit includes a chip ULN2803ADW.

[0008] Preferably, a light emitting diode and a resistor are designed in the input signal indicating unit, and the light emitting diode and the resistor are connected in parallel.

[0009] Preferably, 8 groups of relays are designed in the relay array unit, and the 8 groups of relays are connected in sequence.

[0010] Preferably, the 8-bit output port is designed with an output port and a 24V positive power supply port, and the output port is connected to an anti-signal backflow circuit.

[0011] Preferably, the model of the relay is NY24W-K.

[0012] Preferably, the chip ULN2803ADW is provided with pin terminals 1, pin terminal 2, ..., pin terminal 18; the pin terminals 1-8 are used to connect 8 shaped external input signals, the pin terminal 9 is the neutral terminal, and is connected to the power ground; the pin terminal 10 is the COM terminal, and is connected to the positive pole of the power supply; the pin terminals 11-18 are connected to the input signal indication unit.

[0013] Preferably, a capacitor is further connected between the pin terminal 9 and the pin terminal 10, and the capacitor is a power supply high-frequency bypass capacitor.

[0014] Beneficial effects of the utility model:

[0015] The utility model has a simple circuit structure and low manufacturing cost. It has a large number of I / O port expansions and is easy to connect. It effectively solves the technical defects caused by the fixed number of I / O ports of existing PLCs and does not require the use of multiple PLC hosts. It is suitable for projects with thousands of ports. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of the circuit structure of the circuit board of the utility model;

[0017] Figure 2 This is a schematic diagram of the circuit board of the utility model;

[0018] Figure 3 This is a product structure diagram of the circuit board of this utility model.

[0019] In the figure: 1. Front-end signal terminal; 2. Front-end signal shaping unit; 3. Signal amplitude adjustment unit; 4. Input signal indication unit; 5. Relay array unit; 6. Anti-signal backflow circuit; 7. 8-bit output port. DETAILED DESCRIPTION

[0020] To facilitate understanding of the present invention, a more comprehensive description of the present invention will be provided below with reference to the accompanying drawings. The drawings illustrate preferred embodiments of the present invention. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the present invention.

[0021] Below, the present invention is further described with reference to the accompanying drawings and specific embodiments:

[0022] I / O stands for "input / output." In computer science, I / O describes the movement of data between internal memory and external memory or other peripheral devices. Input is the signal or data received by a system, while output is the signal or data sent from it.

[0023] Example 1:

[0024] like Figure 1 As shown, a PLC I / O expansion circuit board includes a PCB board, on which a front-end signal terminal 1, a front-end signal shaping unit 2, a signal amplitude adjustment unit 3, an input signal indication unit 4, a relay array unit 5, an anti-signal backflow circuit 6 and an 8-bit output port 7 are designed, thereby forming a circuit board with an extended PLC interface; wherein, the upper end of the front-end signal shaping unit 2 is connected to the front-end signal terminal 1, and the lower end is connected to the signal amplitude adjustment unit 3; the upper end of the relay array unit 5 is connected to the input signal indication unit 4, and the lower end is connected to the anti-signal backflow circuit 6; the signal amplitude adjustment unit 2 is further connected to the relay array unit 5 through the input signal indication unit 3, and the lower end of the anti-signal backflow circuit 6 is connected to the 8-bit output port 7, thereby forming a logic circuit with an extended PLC interface.

[0025] Specifically, the front-end signal terminal 1 of this circuit board is designed with 9 ports, namely port 1, port 2, port 3, port 4, port 5, port 6, port 7, port 8 and port 9, among which ports 1 to port 8 are used to connect to external device ends, and port 9 is used to connect to the power ground wire.

[0026] Specifically, 8 groups of front-end signal shaping circuits are designed in the front-end signal shaping unit 2 of this circuit board. The front-end signal shaping circuits are connected to the 8 adjacent ports in the front-end signal terminal. When the input signal from the external device is an AC signal, the front-end signal shaping unit is used to trim it into a DC signal to ensure that both AC and DC input signals can be recognized.

[0027] Specifically, because the amplitudes of input signals from different external devices may vary, a signal amplitude adjustment unit 3 is used to uniformly adjust the 3V to 24V input signal to 24V, thereby facilitating the input signal driving the relay in the subsequent circuit. When a signal is input, the corresponding relay is energized, and vice versa. Whether the relay is energized corresponds to the presence or absence of the input signal. The signal amplitude adjustment unit 3 includes a ULN2803ADW chip, which has 18 groups of pin terminals, namely pin terminal 1, pin terminal 2, ..., pin terminal 17, and pin terminal 18. Pin terminals 1-8 are used to connect the eight shaped external input signals, pin terminal 9 is the neutral terminal and is connected to the power ground line; pin terminal 10 is the COM terminal, typically connected to the positive terminal of the power supply, and pin terminals 11-18 are connected to the input signal indication unit 4. In addition, the capacitor provided between pin terminals 9 and 10 is a high-frequency bypass capacitor for the power supply.

[0028] Specifically, the input signal indication unit 4 is designed with a light-emitting diode and a resistor, which are connected in parallel. When a signal is input, the corresponding light-emitting diode is lit. Specifically, the logic control method of the relay array unit 5 is that when a signal is input, the normally open contact of the corresponding relay is closed. If a signal is added to one end of the normally open contact, the other end of the normally open contact of the relay that is attracted will output a signal, and the other end of the normally open contact of the relay that is not attracted will not output a signal. The relay array unit 5 used is designed with 8 groups of relays, and the relay model is NY24W-K. The 8 groups of relays are connected in sequence. Specifically, the 8 terminals of the 8 relay normally open contacts that add signals are connected in parallel to form one terminal, which is named "output control terminal"; the other 8 terminals are 8 output ports; only when there is a signal input to the "output control" terminal, the output of the output port is valid, otherwise the output port is invalid, that is, the output port is in a high-impedance state.

[0029] Specifically, the anti-signal backflow circuit is used to block the signal backflow of the parallel circuit when there is a parallel circuit at the output port; the 8-bit output port is designed with an output port and a 24V positive power supply port, and the output port is connected to the anti-signal backflow circuit.

[0030] like Figure 2 and Figure 3 The figure shows the principle diagram of the circuit board and a physical structure diagram of the circuit board. The physical structure diagram is not a specific structure diagram of the circuit board. The shape can be improved according to the specific application. The 8-bit expansion port at the front end is used to connect external devices; the 8-bit output port at the back end is connected to the PLC output port; usually 8x2 nBasic unit combinations are used in control systems, where n is a natural number, such as 8 units, 16 units, 32 units, or 64 units. Each port on the front end functions independently, while the back end uses the bit-select ports to multiplex the ports in an 8n fashion. For example, when eight units are used together, each port on the front end functions independently, resulting in 8 x 8 = 64 independent ports that can be connected to external devices. The back end uses the 8n-multiplexed ports, which is equivalent to connecting eight units in parallel. In other words, the eight ports of the eight units are connected in parallel. These 8 x 8 = 64 independent ports become eight multiplexed ports, which are then connected to the eight input ports of the PLC. Furthermore, the output ports of each expansion board connect to the PLC's eight output ports, receiving control signals from the PLC. This allows the PLC to achieve 64 input points using only eight input points. Of course, other combinations are possible to achieve even greater I / O expansion.

[0031] To better understand the technical principles of this utility, specifically, the 64 points at the front end, namely the input terminals, are connected to 64 points of peripheral devices respectively. When the peripheral input signal reaches the corresponding relay coil after shaping and amplitude modulation, if there is a high-level signal input at the input port, the corresponding relay will be energized; in this way, the 64 relays will have their own states of energization or not. To know whether there is an input signal at the 64 input ports, just check the corresponding relay status.

[0032] The 64 relays are divided into 8 groups, and each group of 8 bits shares an "output control" terminal in the byte. If you want to read the data of a certain byte, just add a signal to the "output control" terminal of this byte, such as high or low level. If the relay in the corresponding byte is energized, there will be output, and if it is not energized, there will be no output. In this way, the data of the byte will be output to the PLC. Other bytes that do not have the "output control" signal will not be output and will not affect the existing output.

[0033] Those skilled in the art can make various other corresponding changes and deformations based on the technical solutions and concepts described above, and all of these changes and deformations should fall within the scope of protection of the claims of the present utility model.

Claims

1. A PLC I / O expansion circuit board, comprising a PCB board, wherein the PCB board is designed with a front-end signal terminal, a front-end signal shaping unit, a signal amplitude adjustment unit, an input signal indication unit, a relay array unit, an anti-signal backflow circuit, and an 8-bit output port, characterized in that: The upper end of the front-end signal shaping unit is connected to the front-end signal terminal, and the lower end is connected to the signal amplitude adjustment unit; the upper end of the relay array unit is connected to the input signal indication unit, and the lower end is connected to the anti-signal backflow circuit; the signal amplitude adjustment unit is connected to the relay array unit through the input signal indication unit; the lower end of the anti-signal backflow circuit is connected to the 8-bit output port.

2. A PLC I / O expansion circuit board according to claim 1, characterized in that: The front-end signal terminal is designed with port 1, port 2, ..., port 9, wherein the ports 1 to 8 are used to connect to external device terminals, and the port 9 is used to connect to a power ground wire.

3. The I / O expansion circuit board for PLC according to claim 1, characterized in that: The front-end signal shaping unit is designed with 8 groups of front-end signal shaping circuits, and the front-end signal shaping circuits are connected to 8 adjacent ports in the front-end signal terminal.

4. The I / O expansion circuit board for PLC according to claim 1, characterized in that: The signal amplitude adjustment unit includes a chip ULN2803ADW.

5. The I / O expansion circuit board for PLC according to claim 1, characterized in that: A light emitting diode and a resistor are designed in the input signal indicating unit, and the light emitting diode and the resistor are connected in parallel.

6. The I / O expansion circuit board for PLC according to claim 1, characterized in that: The relay array unit is designed with 8 groups of relays, and the 8 groups of relays are connected in sequence.

7. The I / O expansion circuit board for PLC according to claim 1, characterized in that: The 8-bit output port is designed with an output port and a 24V positive power supply port, and the output port is connected to an anti-signal backflow circuit.

8. The I / O expansion circuit board for PLC according to claim 6, characterized in that: The model of the relay is NY24W-K.

9. The I / O expansion circuit board for PLC according to claim 4, characterized in that: The chip ULN2803ADW is provided with pin terminals 1, pin terminal 2, ..., pin terminal 18; the pin terminals 1-8 are used to connect 8 shaped external input signals, the pin terminal 9 is the neutral terminal and is connected to the power ground; the pin terminal 10 is the COM terminal and is connected to the positive pole of the power supply; the pin terminals 11-18 are connected to the input signal indication unit.

10. The I / O expansion circuit board for PLC according to claim 9, characterized in that: A capacitor is further connected between the pin terminal 9 and the pin terminal 10 , and the capacitor is a power supply high-frequency bypass capacitor.

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