Printer communication and scram multiplexing circuit

Abstract

The invention discloses a printer communication and scram multiplexing circuit which comprises a scram switch circuit arranged at the input end of a differential communication circuit and a scram signal detection circuit, so that the scram switch circuit and the scram signal detection circuit multiplex a communication line of the differential communication circuit. The differential communication circuit is used for outputting a communication signal according to a preset communication protocol; the emergency stop switch circuit is connected with the input end of the differential communication circuit in parallel, the other end of the emergency stop switch circuit is connected with a grounding end, the emergency stop signal detection circuit is connected with the output end of the differential communication circuit in parallel, and the other end of the emergency stop signal detection circuit is connected with the cut-off switch. The emergency stop signal detection circuit is used for receiving a to-be-detected signal of the output end of the differential communication circuit and generating an emergency stop signal when it is judged that a low-level data bit continuously output in the to-be-detected signal is larger than a data bit threshold value. According to the invention, printer communication and sudden stop signal detection are realized, and low-delay and high-reliability braking requirements are met.

Description

Technical Field

[0001] The invention belongs to the field of industrial control, and in particular relates to a printer communication and emergency stop multiplexing circuit. Background Art

[0002] At present, when a printer fails during use, the driver circuit is usually powered off directly. This operation is prone to two hidden dangers: first, it is difficult for the internal mechanical parts of the printer to stop quickly; second, the driver circuit of the printer is easily damaged in an instant due to huge current changes, causing failures and safety hazards.

[0003] The emergency stop circuit is a safety circuit used to stop the operation of equipment in an emergency. It can immediately cut off the power supply and stop the operation of the equipment through a special switch or button to protect the safety of personnel and equipment. Usually the emergency stop switch is directly connected to the power supply end, and the emergency control power supply can be disconnected through the emergency stop button to avoid accidents. In order to facilitate remote control, traditional emergency stop buttons are usually equipped with independent signal transceiver mechanisms. In order to simplify the structure, some emergency stop circuits even share a set of transceiver mechanisms with the power supply of the equipment itself.

[0004] The Chinese patent "A Printer Emergency Stop Circuit" with application number 201920168056.6 controls the voltage transmission from the power supply device to the control circuit through the first emergency stop switch, and controls the voltage transmitted from the control circuit to the drive circuit through the second emergency stop switch. As long as either the first emergency stop switch or the second emergency stop switch is disconnected, the drive circuit cannot be turned on, and the printer cannot be driven, thereby achieving the purpose of emergency stop, making the emergency stop operation of the printer safer and more stable, thereby optimizing the emergency stop performance of the printer. However, this method is only used for the local machine and cannot adapt to the remote operation printing system with a long distance between the sending end and the receiving end, especially when an error in data transmission is found and emergency braking is required, the traditional emergency stop circuit cannot meet the low-latency and high-reliability braking time control. Summary of the invention

[0005] In order to solve the above problems existing in the prior art, the present invention provides a printer communication and emergency stop multiplexing circuit. The technical problem to be solved by the present invention is achieved through the following technical solutions:

[0006] A printer communication and emergency stop multiplexing circuit, comprising:

[0007] An emergency stop switch circuit is arranged at the input end of the differential communication circuit, and an emergency stop signal detection circuit is arranged at the output end of the differential communication circuit, so that the emergency stop switch circuit and the emergency stop signal detection circuit reuse the communication line of the differential communication circuit, and the differential communication circuit is used to output a communication signal according to a preset communication protocol;

[0008] The emergency stop switch circuit is connected in parallel with the input end of the differential communication circuit, and the other end of the emergency stop switch circuit is connected to the ground end, so that when the emergency stop switch circuit is closed, the communication signal at the input end of the differential communication circuit is output to the ground end, or when the emergency stop trigger circuit is disconnected, the communication signal at the input end of the differential communication circuit is output to the output end of the differential communication circuit;

[0009] The emergency stop signal detection circuit is connected in parallel with the output end of the differential communication circuit, and the other end of the emergency stop signal detection circuit is connected to a circuit breaker. The emergency stop signal detection circuit is used to receive the signal to be detected at the output end of the differential communication circuit. When it is determined that the continuously output low-level data bits in the signal to be detected are greater than the data bit threshold, an emergency stop signal is generated to drive the circuit breaker to work according to the emergency stop signal.

[0010] In a specific embodiment, the emergency stop signal detection circuit includes a level signal input pin, a clock input pin, a detection state indication pin and an emergency stop signal output pin;

[0011] The clock input pin is used to input a clock signal;

[0012] The level signal input pin is used to receive the signal to be detected;

[0013] The detection status indication pin is used to compare the level of the signal to be detected with the clock signal in each clock cycle. When the signal to be detected is judged to be at a low level, the detection status indication pin outputs a high level, and the counter records the number of consecutive high level outputs. Alternatively, when the signal to be detected is judged to be at a high level, the detection status indication pin outputs a low level, and the counter is reset to zero. When it is judged that the number of times recorded by the counter reaches a data bit threshold, the detection status indication pin generates an emergency stop signal, and outputs the emergency stop signal to the emergency stop signal output pin;

[0014] The emergency stop signal output pin is used to control the pin to output a high level when receiving an emergency stop signal, so as to drive the circuit breaker to work.

[0015] In a specific embodiment, a reset pin is also included, and the reset pin is used to control the detection status indication pin to stop detection and control the emergency stop switch circuit to an open state when it is detected that the emergency stop signal output pin is at a high level and the emergency stop switch circuit is in a closed state.

[0016] In a specific implementation, the data bit threshold is determined according to the maximum continuous number of low levels of the data stream in a preset communication protocol.

[0017] In a specific implementation, the preset communication protocol is a differential signal communication protocol.

[0018] In a specific implementation, the data bit threshold is 10.

[0019] In a specific implementation, the communication line is a USB / ETHERNET differential cable.

[0020] Beneficial effects of the present invention:

[0021] The printer communication and emergency stop multiplexing circuit of the present invention multiplexes the communication line of the differential communication circuit through an emergency stop switch circuit arranged at the input end of the printer differential communication circuit and an emergency stop signal detection circuit arranged at the output end of the differential communication circuit, wherein the differential communication circuit is used to output a communication signal according to a preset communication protocol; the emergency stop switch circuit is connected in parallel with the input end of the differential communication circuit, and the other end of the emergency stop switch circuit is connected to the ground end, so that when the emergency stop switch circuit is closed, the communication signal at the input end of the differential communication circuit is output to the ground end, or when the emergency stop trigger circuit is disconnected, the communication signal at the input end of the differential communication circuit is output to the output end of the differential communication circuit; the emergency stop signal detection circuit is connected in parallel with the output end of the differential communication circuit, and the other end of the emergency stop signal detection circuit is connected to a circuit breaker, and the emergency stop signal detection circuit is used to receive a signal to be detected at the output end of the differential communication circuit, and when it is determined that the continuously output low-level data bits in the signal to be detected are greater than the data bit threshold, an emergency stop signal is generated to drive the circuit breaker to work according to the emergency stop signal. In this way, the communication and emergency stop signal detection can be achieved by multiplexing the communication circuit. There is no need to set up a separate lead for the emergency stop function, and the working condition of the communication line can be monitored at the same time to meet the low-latency and high-reliability braking requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of a communication and emergency stop multiplexing circuit provided by an embodiment of the present invention;

[0023] Figure 2 is a schematic diagram of an emergency stop signal detection circuit provided by an embodiment of the present invention;

[0024] Figure 3 It is a schematic diagram of an emergency stop differential multiplexing circuit structure provided by an embodiment of the present invention;

[0025] Figure 4 It is a differential signal communication protocol data bit illustration diagram provided by an embodiment of the present invention;

[0026] Figure 5 It is a waveform diagram of a Keyin signal inputted by a receiving end during communication provided by an embodiment of the present invention;

[0027] Figure 6 is a waveform diagram of a Clk clock signal during communication provided by an embodiment of the present invention;

[0028] Figure 7 It is an output waveform diagram of a Key_state detection circuit working state indication during communication provided by an embodiment of the present invention, and a detection is performed once;

[0029] Figure 8 It is an output waveform diagram of Key_flag outputting a low level during communication provided by an embodiment of the present invention, and no emergency stop signal is detected;

[0030] Fig. 9 It is a waveform diagram of a Keyin signal inputted by a receiving end when an emergency stop is pressed provided by an embodiment of the present invention;

[0031] Fig.10 It is a Clk clock signal waveform diagram when the emergency stop is pressed provided by an embodiment of the present invention;

[0032] Fig.11 It is an output waveform diagram of a detection when the emergency stop is pressed, indicating the working state of the Key_state detection circuit provided by the embodiment of the present invention;

[0033] Fig.12 It is an output waveform diagram of the emergency stop signal detected when Key_flag outputs a high level when the emergency stop is pressed provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0034] The present invention is further described in detail below with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.

[0035] Embodiment 1

[0036] See also Figure 1 , Figure 1 The present invention provides a printer communication and emergency stop multiplexing circuit schematic diagram, including:

[0037] An emergency stop switch circuit is arranged at the input end of the differential communication circuit, and an emergency stop signal detection circuit is arranged at the output end of the differential communication circuit, so that the emergency stop switch circuit and the emergency stop signal detection circuit reuse the communication line of the differential communication circuit, and the differential communication circuit is used to output a communication signal according to a preset communication protocol;

[0038] The emergency stop switch circuit is connected in parallel with the input end of the differential communication circuit, and the other end of the emergency stop switch circuit is connected to the ground end, so that when the emergency stop switch circuit is closed, the communication signal at the input end of the differential communication circuit is output to the ground end, or when the emergency stop trigger circuit is disconnected, the communication signal at the input end of the differential communication circuit is output to the output end of the differential communication circuit;

[0039] That is, since the differential communication circuit is multiplexed, when the emergency stop switch circuit is disconnected (ie, not working), the communication circuit works normally and transmits data normally. When the emergency stop switch circuit is closed, the communication circuit stops working immediately.

[0040] The emergency stop signal detection circuit is connected in parallel with the output end of the differential communication circuit, and the other end of the emergency stop signal detection circuit is connected to the circuit breaker. The emergency stop signal detection circuit is used to receive the signal to be detected at the output end of the differential communication circuit. When it is judged that the continuously output low-level data bits in the signal to be detected are greater than the data bit threshold, an emergency stop signal is generated to drive the circuit breaker to work according to the emergency stop signal. Since the communication signal cannot be sent to the output end normally when the emergency stop circuit is working, the output end cannot receive valid information at this time, so it can only output low-level data.

[0041] In one specific embodiment, see Figure 2 , Figure 2 1 is a schematic diagram of a printer emergency stop signal detection circuit provided by an embodiment of the present invention, wherein the emergency stop signal detection circuit comprises a level signal input pin Key_in, a clock input pin Clk, a detection state indication pin Key_state and an emergency stop signal output pin Key_flag;

[0042] The clock input pin Clk is used to input a clock signal, the clock signal is generated by a crystal oscillator or other clock components, and the clock signal continuously outputs square wave information, each square wave represents a clock cycle;

[0043] The level signal input pin Key_in is used to receive the signal to be detected. It should be noted that, when communication is normal, the signal to be detected is the communication signal sent by the output end of the differential communication circuit. When the communication is interrupted due to the closure of the emergency stop switch circuit, the communication signal cannot be output to the level signal input pin Key_in, so the pin continues to be at a low level. In addition, it should be noted that if the communication is abnormal, such as an error in the transmission of the communication data frame, even if the emergency stop switch circuit is not closed, it may cause the pin to continue to be at a low level. Therefore, the low level detection is not necessarily caused by the emergency stop switch circuit. In this scenario, an emergency stop signal will also be generated due to the communication abnormality, thereby avoiding data security risks caused by the communication abnormality.

[0044] The detection state indication pin Key_state is used to compare the level of the signal to be detected with the level of the clock signal in each clock cycle. When the signal to be detected is judged to be a low level, the detection state indication pin Key_state outputs a high level, and the counter records the number of consecutive high level outputs, or when the signal to be detected is judged to be a high level, the detection state indication pin Key_state outputs a low level, and the counter is reset to zero, until it is judged that the number of times recorded by the counter reaches the data bit threshold, the detection state indication pin Key_state generates an emergency stop signal, and outputs the emergency stop signal to the emergency stop signal output pin Key_flag; since the clock input pin Clk continuously outputs a high level signal, by performing a logical operation (such as an AND operation) on the high level signal and the signal to be detected, it can be judged that the signal to be detected corresponds to a high level signal or a low level signal. In order for the operation result to simultaneously reflect the abnormality of the communication data, the present application compares the signal of at least one data frame length, so as to simultaneously judge the transmission error caused by the emergency stop switch circuit or other communication data abnormalities. The present embodiment is described with the preset communication protocol as the differential communication protocol. The data frame of the protocol includes 1 start bit, 7 valid data bits, 1 parity bit, 1 stop bit and 1 idle bit, wherein the stop bit and the idle bit are both 1 (i.e., high level). In extreme cases, the first 10 bits may all be 0 (i.e., low level). Therefore, the data bit threshold value set in the present embodiment is 10. Of course, different data transmission protocols are also different. Specifically, the data bit threshold value is determined according to the maximum continuous number of low levels of the data stream in the preset communication protocol. In other words, when the communication signal is transmitted normally, there will be no situation where 10 consecutive clock cycles are all low levels. Otherwise, either the emergency stop switch circuit causes the communication signal to be unable to be transmitted, or the signal has a transmission anomaly during transmission, and both situations require an emergency stop operation. If a high level appears when less than ten low levels occur, this indicates that the data is transmitted normally, and it is necessary to re-accumulate the count.

[0045] The emergency stop signal output pin Key_flag is used to control the pin to output a high level when receiving an emergency stop signal, so as to drive the circuit breaker to work.

[0046] In a specific embodiment, a reset pin is also included. The reset pin is used to control the detection state indication pin Key_state to stop detection and control the emergency stop switch circuit to be in an open state when the emergency stop signal output pin Key_flag is detected to be at a high level and the emergency stop switch circuit is in a closed state. When the emergency stop signal output pin Key_flag is at a high level, it indicates that an emergency stop has been made. At this time, the level signal input pin Key_in will always output a low level. Therefore, there is no need for detection, so the detection is stopped. The emergency stop may be caused by the closure of the emergency stop switch circuit, or it may be caused by transmission abnormality in the signal transmission. If it is the latter, the emergency stop switch circuit is still in an open state, and there is no need to reset the emergency stop switch circuit. If it is the former, the emergency stop switch circuit is in a closed state, and it is necessary to reset the emergency stop switch circuit, thereby avoiding the problem that the emergency stop signal cannot be canceled when the circuit is connected again.

[0047] The communication and emergency stop multiplexing circuit of this embodiment can use the communication circuit at the same time to realize the detection of communication and emergency stop signals. There is no need to set up leads for the emergency stop function separately, and it can monitor the working conditions of the communication lines at the same time to meet the braking requirements of low latency and high reliability.

[0048] Embodiment 2

[0049] Circuit based on USB / ETHERNET differential line Figure 3 As shown, Vcc is the voltage source, GND is the ground terminal, R and D represent the signal receiving and sending terminals respectively. At the sending terminal of the emergency stop circuit, the emergency stop button is connected in parallel with the sending pin of the processor communication interface. The emergency stop button is usually in an open circuit state and does not affect the processor communication. When the emergency stop button is pressed, the button is connected to the ground, so that the sending pin of the communication interface is connected to the ground, and the receiving end also receives a continuous low level. At the receiving end of the emergency stop circuit, the receiving pin of the USB / ETHERNET interface is connected to a low-level detection circuit. This circuit detects whether it is communication data or an emergency stop signal from the communication data stream. The communication data is a high and low level that changes bit by bit. The emergency stop signal detection circuit detects that the received signal is at a low level for more than 10 units, then it is judged as an emergency stop signal, triggering the output of a low level. The low level connects the emergency stop switch circuit to achieve an emergency stop. During normal communication, please refer to Figure 4 , Figure 4This is a differential signal communication protocol data bit illustration diagram provided by an embodiment of the present invention. The receiving circuit outputs high and low levels according to the USB / ETHERNET protocol. The low level duration does not exceed 10 data bits (only when sending 0x00), and does not exceed 9 data bits when there is no check. According to the USB communication 12Mbps baud rate, the low level time does not exceed 10*(1 / 12000000)=8ns. That is, the emergency stop signal detection delay does not exceed 8ns. The receiving signal low level detection circuit triggers the detection at a low level, continuously detects 10 CLK cycles as a low level, and outputs an emergency stop signal.

[0050] For details, see Figure 5 and Fig. 9 , Keyin is the waveform signal input to the receiving end, and the detection circuit detects whether the signal is an emergency stop signal.

[0051] For details, see Figure 6 and Fig.10 , Clk is the clock input for the detection circuit, which is generated by a crystal oscillator or other clock components, or can be generated inside the detection circuit.

[0052] Rst_n is the forced reset pin of the emergency stop signal detection circuit, which forces the circuit to reset and obtain the initialization state.

[0053] For details, see Figure 7 and Fig.11 , Key_state is the working status indication of the emergency stop signal detection circuit. Output 0 means no detection, no low-level signal is detected. Output 1 means a low-level signal is detected and it is determining whether to make an emergency stop. It takes 10 clock cycles to detect the emergency stop signal.

[0054] For details, see Figure 8 and Fig.12 , Key_flag is the emergency stop signal. If the emergency stop signal detection circuit detects an emergency stop, it outputs a high level 1 and maintains a high level, which can drive the circuit breaker. If no emergency stop signal is detected, it maintains a low level and outputs 0.

[0055] After emergency stop, the emergency stop signal can be cancelled only when a low level is input to Rst_n to force the circuit to reset, and Key_flag outputs a low level. Otherwise, Key_flag maintains the original trigger state and outputs a high level.

[0056] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. A printer communication and emergency stop multiplexing circuit, characterized in that: include: An emergency stop switch circuit is arranged at the input end of the differential communication circuit, and an emergency stop signal detection circuit is arranged at the output end of the differential communication circuit, so that the emergency stop switch circuit and the emergency stop signal detection circuit reuse the communication line of the differential communication circuit, and the differential communication circuit is used to output a communication signal according to a preset communication protocol; The emergency stop switch circuit is connected in parallel with the input end of the differential communication circuit, and the other end of the emergency stop switch circuit is connected to the ground end, so that when the emergency stop switch circuit is closed, the communication signal at the input end of the differential communication circuit is output to the ground end, or when the emergency stop trigger circuit is disconnected, the communication signal at the input end of the differential communication circuit is output to the output end of the differential communication circuit; The emergency stop signal detection circuit is connected in parallel with the output end of the differential communication circuit, and the other end of the emergency stop signal detection circuit is connected to a circuit breaker. The emergency stop signal detection circuit is used to receive the signal to be detected at the output end of the differential communication circuit. When it is determined that the continuously output low-level data bits in the signal to be detected are greater than the data bit threshold, an emergency stop signal is generated to drive the circuit breaker to work according to the emergency stop signal.

2. The printer communication and emergency stop multiplexing circuit according to claim 1, characterized in that: The emergency stop signal detection circuit includes a level signal input pin, a clock input pin, a detection state indication pin and an emergency stop signal output pin; The clock input pin is used to input a clock signal; The level signal input pin is used to receive the signal to be detected; The detection status indication pin is used to compare the level of the signal to be detected with the clock signal in each clock cycle. When the signal to be detected is judged to be at a low level, the detection status indication pin outputs a high level, and the counter records the number of consecutive high level outputs. Alternatively, when the signal to be detected is judged to be at a high level, the detection status indication pin outputs a low level, and the counter is reset to zero. When it is judged that the number of times recorded by the counter reaches a data bit threshold, the detection status indication pin generates an emergency stop signal, and outputs the emergency stop signal to the emergency stop signal output pin; The emergency stop signal output pin is used to control the pin to output a high level when receiving an emergency stop signal, so as to drive the circuit breaker to work.

3. The printer communication and emergency stop multiplexing circuit according to claim 1, characterized in that: It also includes a reset pin, which is used to control the detection status indication pin to stop detection and control the emergency stop switch circuit to an open state when it is detected that the emergency stop signal output pin is at a high level and the emergency stop switch circuit is in a closed state.

4. The printer communication and emergency stop multiplexing circuit according to claim 1, characterized in that: The data bit threshold is determined according to the maximum continuous number of low-level data streams in a preset communication protocol.

5. The printer communication and emergency stop multiplexing circuit according to claim 4, characterized in that: The preset communication protocol is a differential signal communication protocol.

6. The printer communication and emergency stop multiplexing circuit according to claim 5, characterized in that: The data bit threshold is 10.

7. The printer communication and emergency stop multiplexing circuit according to claim 1, characterized in that: The communication line is a USB / ETHERNET differential cable.

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