A printer communication and emergency stop multiplexing circuit

Abstract

This invention discloses a printer communication and emergency stop multiplexing circuit, including an emergency stop switch circuit disposed at the input terminal of a differential communication circuit, and an emergency stop signal detection circuit. The emergency stop switch circuit and the emergency stop signal detection circuit multiplex the communication lines of the differential communication circuit. The differential communication circuit outputs communication signals according to a preset communication protocol. The emergency stop switch circuit is connected in parallel to the input terminal of the differential communication circuit, and its other end is connected to a ground terminal. The emergency stop signal detection circuit is connected in parallel to the output terminal of the differential communication circuit, and its other end is connected to a circuit breaker. The emergency stop signal detection circuit receives the signal to be detected from the output terminal of the differential communication circuit. When it is determined that the number of consecutively output low-level data bits in the signal to be detected is greater than a data bit threshold, an emergency stop signal is generated. This invention realizes printer communication and emergency stop signal detection, meeting the braking requirements of low latency and high reliability.

Description

Technical Field

[0001] This invention belongs to the field of industrial control, specifically relating to a printer communication and emergency stop multiplexing circuit. Background Technology

[0002] Currently, when a printer malfunctions, the common approach is to directly cut off the power to the drive circuit. This operation can easily lead to two potential problems: firstly, it's difficult for the printer's internal mechanical components to stop quickly; and secondly, the printer's drive circuit is susceptible to damage from sudden, large current changes, resulting in malfunctions and safety hazards.

[0003] An emergency stop circuit is a safety circuit used to stop equipment operation in an emergency. It uses a special switch or button to immediately cut off power and stop the equipment, protecting personnel and equipment. Typically, the emergency stop switch is directly connected to the power supply, while the emergency stop button disconnects the emergency control power, thus preventing accidents. For convenient remote control, traditional emergency stop buttons usually have an independent signal transceiver mechanism; to simplify the structure, some emergency stop circuits even share a transceiver mechanism with the equipment's power supply.

[0004] Chinese patent application number 201920168056.6, entitled "A Printer Emergency Stop Circuit," uses a first emergency stop switch to control the voltage supply from the power supply device to the control circuit, and a second emergency stop switch to control the voltage supplied from the control circuit to the drive circuit. If either the first or second emergency stop switch is disconnected, the drive circuit cannot conduct, thus preventing the printer from being driven and achieving an emergency stop. This makes the printer's emergency stop operation safer and more stable, thereby optimizing the printer's emergency stop performance. However, this method is only applicable to the local machine and cannot be adapted to remote printing systems where the sending and receiving ends are far apart. Especially when an error in data transmission requires emergency braking, traditional emergency stop circuits cannot meet the requirements of low-latency, high-reliability braking time control. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, this invention provides a printer communication and emergency stop multiplexing circuit. The technical problem to be solved by this invention is achieved through the following technical solution:

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

[0007] An emergency stop switch circuit located at the input terminal of the differential communication circuit and an emergency stop signal detection circuit located at the output terminal of the differential communication circuit are provided such that the emergency stop switch circuit and the emergency stop signal detection circuit reuse the communication line of the differential communication circuit. The differential communication circuit is used to output communication signals according to a preset communication protocol.

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

[0009] The emergency stop signal detection circuit is connected in parallel with the output 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 from the output of the differential communication circuit. When it is determined that the number of consecutive low-level data bits in the signal to be detected is 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 one specific embodiment, the emergency stop signal detection circuit includes a level signal input pin, a clock input pin, a detection status indicator pin, and an emergency stop signal output pin;

[0011] The clock input pin is used to input clock signals;

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

[0013] The detection status indicator pin 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 determined to be low, the detection status indicator pin outputs a high level, and the counter records the number of consecutive high-level outputs. Alternatively, when the signal to be detected is determined to be high, the detection status indicator pin outputs a low level, and the counter count is reset to zero. When the count recorded by the counter reaches the data bit threshold, the detection status indicator 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 its pin to output a high level when an emergency stop signal is received, so as to drive the circuit breaker to work.

[0015] In one specific embodiment, a reset pin is also included, which is used to control the detection status indicator pin to stop detection and control the emergency stop switch circuit to open when the emergency stop signal output pin is detected to be high and the emergency stop switch circuit is closed.

[0016] In one specific implementation, the data bit threshold is determined based on the maximum duration of a low-level data stream in a preset communication protocol.

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

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

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

[0020] The beneficial effects of this invention are:

[0021] The printer communication and emergency stop multiplexing circuit of the present invention uses an emergency stop switch circuit located at the input terminal of the printer differential communication circuit and an emergency stop signal detection circuit located at the output terminal of the differential communication circuit. This allows the emergency stop switch circuit and the emergency stop signal detection circuit to multiplex the communication lines of the differential communication circuit. The differential communication circuit outputs communication signals according to a preset communication protocol. The emergency stop switch circuit is connected in parallel to the input terminal of the differential communication circuit, and the other end of the emergency stop switch circuit is connected to a ground terminal. This ensures that when the emergency stop switch circuit is closed, the communication signal at the input terminal of the differential communication circuit is output to the ground terminal; or when the emergency stop trigger circuit is open, the communication signal at the input terminal of the differential communication circuit is output to the output terminal of the differential communication circuit. The emergency stop signal detection circuit is connected in parallel to the output terminal 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 receives the signal to be detected at the output terminal of the differential communication circuit. When it is determined that the number of consecutively output low-level data bits in the signal to be detected is greater than a data bit threshold, an emergency stop signal is generated to drive the circuit breaker to operate according to the emergency stop signal. In this way, communication and emergency stop signal detection can be achieved by reusing the communication circuit, eliminating the need to set up separate leads for the emergency stop function, and simultaneously monitoring the operation of the communication line, thus meeting the braking requirements of low latency and high reliability. Attached Figure Description

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

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

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

[0025] Figure 4 This is a diagram illustrating the data bits of a differential signal communication protocol provided in an embodiment of the present invention;

[0026] Figure 5 This is a waveform diagram of the Keyin signal input at the receiving end during communication provided in an embodiment of the present invention;

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

[0028] Figure 7 This is the output waveform diagram of the Key_state detection circuit working status indication during communication provided in the embodiment of the present invention, which is a detection output waveform diagram.

[0029] Figure 8 This is the output waveform diagram of Key_flag being low during communication provided in the embodiment of the present invention, indicating that no emergency stop signal was detected;

[0030] Figure 9 This is a waveform diagram of the Keyin signal input to the receiving end when the emergency stop button is pressed, provided in an embodiment of the present invention.

[0031] Figure 10 This is a waveform diagram of the Clk clock signal when the emergency stop button is pressed, provided in an embodiment of the present invention.

[0032] Figure 11 This is the output waveform diagram of the Key_state detection circuit working status indication when the emergency stop is pressed, provided in the embodiment of the present invention, for a single detection.

[0033] Figure 12 This is the output waveform diagram of Key_flag outputting a high level when the emergency stop is pressed, as provided in the embodiment of the present invention, indicating that an emergency stop signal has been detected. Detailed Implementation

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

[0035] Example 1

[0036] Please see Figure 1 , Figure 1 This is a schematic diagram of a printer communication and emergency stop multiplexing circuit provided in an embodiment of the present invention, including:

[0037] An emergency stop switch circuit located at the input terminal of the differential communication circuit and an emergency stop signal detection circuit located at the output terminal of the differential communication circuit are provided such that the emergency stop switch circuit and the emergency stop signal detection circuit reuse the communication line of the differential communication circuit. The differential communication circuit is used to output communication signals according to a preset communication protocol.

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

[0039] In other words, because the differential communication circuit is multiplexed, the communication circuit operates normally and transmits data normally when the emergency stop switch circuit is open (i.e., not working). However, when the emergency stop switch circuit is closed, the communication circuit immediately stops working.

[0040] The emergency stop signal detection circuit is connected in parallel to the output 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 receives the signal to be detected from the output of the differential communication circuit. When it is determined that the number of consecutive low-level data bits output in the signal to be detected is greater than the data bit threshold, an emergency stop signal is generated to drive the circuit breaker to operate according to the emergency stop signal. Since the communication signal cannot be sent normally to the output when the emergency stop circuit is working, the output cannot receive valid information at this time, so it can only output low-level data.

[0041] In one specific implementation, please refer to Figure 2 , Figure 2 This is a schematic diagram of a printer emergency stop signal detection circuit provided in an embodiment of the present invention. The emergency stop signal detection circuit includes a level signal input pin Key_in, a clock input pin Clk, a detection status indicator 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, which is generated by a crystal oscillator or other clock components. The clock signal continuously outputs square wave information, with each square wave representing one clock cycle.

[0043] The level signal input pin Key_in is used to receive the signal to be detected. It should be noted that during normal communication, the signal to be detected is the communication signal sent by the output of the differential communication circuit. However, when 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 remains at a low level. In addition, it should be noted that if communication is abnormal, such as an error in the transmission of communication data frames, even if the emergency stop switch circuit is not closed, the pin may still remain 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 still be generated due to communication abnormality to avoid data security risks caused by communication abnormality.

[0044] The detection status indicator pin Key_state is used to compare the level of the signal to be detected with that of the clock signal in each clock cycle. When the signal to be detected is determined to be low, the detection status indicator pin Key_state outputs a high level, and a counter records the number of consecutive high-level outputs. Alternatively, when the signal to be detected is determined to be high, the detection status indicator pin Key_state outputs a low level, and the counter count is reset to zero. When the count recorded by the counter reaches the data bit threshold, the detection status indicator 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 (e.g., AND operation) between this high-level signal and the signal to be detected, it can be determined whether 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 communication data abnormality, this application compares a signal of at least one data frame length, thereby being able to simultaneously determine the transmission error caused by the emergency stop switch circuit or other communication data abnormalities. This embodiment uses a differential communication protocol as the preset communication protocol. The data frame of this protocol includes 1 start bit, 7 valid data bits, 1 parity bit, 1 stop bit, and 1 idle bit. The stop bit and idle bit are both 1 (high level). In extreme cases, the first 10 bits may all be 0 (low level). Therefore, the data bit threshold set in this embodiment is 10. Of course, different data transmission protocols will differ. Specifically, the data bit threshold is determined based on the maximum number of consecutive low-level cycles in the preset communication protocol. That is, during normal communication signal transmission, there will not be a situation where 10 consecutive clock cycles are low. Otherwise, either the emergency stop switch circuit prevents the communication signal from transmitting, or there is a transmission abnormality during signal transmission, both of which require an emergency stop operation. If a high level appears after less than ten low-level cycles, it indicates normal data transmission, and the count needs to be reset.

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

[0046] In one specific embodiment, a reset pin is also included. This reset pin is used to control the detection state indicator pin Key_state to stop detection and to 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 high and the emergency stop switch circuit is closed. When the emergency stop signal output pin Key_flag is high, it indicates that an emergency stop has already occurred. At this time, the level signal input pin Key_in will always output a low level, so there is no need for detection, and detection is stopped. Since an emergency stop may be caused by the emergency stop switch circuit being closed or by a transmission abnormality, if it is the latter, the emergency stop switch circuit remains in an open state and does not need to be reset. If it is the former, the emergency stop switch circuit is in a closed state and needs to be reset, thereby avoiding the problem of the emergency stop signal not being canceled when the circuit is reconnected.

[0047] The communication and emergency stop multiplexing circuit in this embodiment can simultaneously use the communication circuit to detect communication and emergency stop signals, without the need to set up separate leads for the emergency stop function, and can simultaneously monitor the operation of the communication line, meeting the braking requirements of low latency and high reliability.

[0048] Example 2

[0049] Circuits based on USB / ETHERNET differential lines, such as Figure 3 As shown, Vcc is the voltage source, GND is the ground terminal, and R and D represent the signal receiving and transmitting terminals, respectively. The emergency stop circuit's transmitting terminal connects the emergency stop button in parallel with the processor's communication interface transmitting pin. The emergency stop button is normally in an open circuit state, not affecting processor communication. When the emergency stop button is pressed, it connects to ground, thus connecting the communication interface transmitting pin to ground, and the receiving terminal receives a continuous low level. The emergency stop circuit's receiving terminal connects the USB / ETHERNET interface's receiving pin to a low-level detection circuit. This circuit detects whether the data stream contains communication data or an emergency stop signal. Communication data consists of bit-varying high and low levels. The emergency stop signal detection circuit detects a received signal that remains low for more than 10 units; if so, it determines it is an emergency stop signal, triggering a low-level output. This low level activates the emergency stop switch circuit, achieving an emergency stop. During normal communication, please refer to [link to relevant documentation]. Figure 4 , Figure 4This is a data bit illustration diagram of a differential signal communication protocol provided in an embodiment of the present invention. The receiving circuit outputs high and low levels according to the USB / ETHERNET protocol. The duration of the low level is no more than 10 data bits (only when sending 0x00), and no more than 9 data bits when there is no checksum. Calculated based on a USB communication baud rate of 12Mbps, 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 detection with a low level. If a low level is detected continuously for 10 CLK cycles, an emergency stop signal is output.

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

[0051] For details, please see Figure 6 and Figure 10 Clk is the clock input used by the detection circuit. It can be generated by a crystal oscillator or other clock components, or it can be generated internally by the detection circuit.

[0052] Rst_n is the forced reset pin of the emergency stop signal detection circuit. The circuit is forced to reset and obtain the initial state.

[0053] For details, please see Figure 7 and Figure 11 Key_state indicates the working status of the emergency stop signal detection circuit. An output of 0 indicates that no detection is being performed and no low-level signal has been detected. An output of 1 indicates that a low-level signal has been detected and the circuit is determining whether to perform an emergency stop. Detecting an emergency stop signal requires 10 clock cycles.

[0054] For details, please see Figure 8 and Figure 12 Key_flag is the emergency stop signal. If the emergency stop signal detection circuit detects an emergency stop, it outputs a high level of 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 an emergency stop, the emergency stop signal can only be canceled by inputting a low level to Rst_n to force the circuit to reset, at which point Key_flag will output a low level. Otherwise, Key_flag will retain its original trigger state and output a high level.

[0056] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A printer communication and emergency stop multiplexing circuit, characterized in that, include: An emergency stop switch circuit located at the input terminal of the differential communication circuit and an emergency stop signal detection circuit located at the output terminal of the differential communication circuit are provided such that the emergency stop switch circuit and the emergency stop signal detection circuit reuse the communication line of the differential communication circuit. The differential communication circuit is used to output communication signals according to a preset communication protocol. The emergency stop switch circuit is connected in parallel with the input terminal of the differential communication circuit, and the other end of the emergency stop switch circuit is connected to the ground terminal, so that when the emergency stop switch circuit is closed, the communication signal of the input terminal of the differential communication circuit is output to the ground terminal, or when the emergency stop switch circuit is open, the communication signal of the input terminal of the differential communication circuit is output to the output terminal of the differential communication circuit. The emergency stop signal detection circuit is connected in parallel with the output 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 of the differential communication circuit. When it is determined that the number of continuously output low-level data bits in the signal to be detected is 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. The emergency stop signal detection circuit includes a level signal input pin, a clock input pin, a detection status indicator pin, and an emergency stop signal output pin. The clock input pin is used to input clock signals; The level signal input pin is used to receive the signal to be detected; The detection status indicator pin 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 determined to be low, the detection status indicator pin outputs a high level, and the counter records the number of consecutive high-level outputs. Alternatively, when the signal to be detected is determined to be high, the detection status indicator pin outputs a low level, and the counter count is reset to zero. When the count recorded by the counter reaches the data bit threshold, the detection status indicator 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 its pin to output a high level when an emergency stop signal is received, so as to drive the circuit breaker to work.

2. 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 indicator pin to stop detection and control the emergency stop switch circuit to open when the emergency stop signal output pin is detected to be high and the emergency stop switch circuit is closed.

3. The printer communication and emergency stop multiplexing circuit according to claim 1, characterized in that, The data bit threshold is determined based on the maximum duration of a low-level data stream in a preset communication protocol.

4. The printer communication and emergency stop multiplexing circuit according to claim 3, characterized in that, The preset communication protocol is a differential signal communication protocol.

5. The printer communication and emergency stop multiplexing circuit according to claim 4, characterized in that, The data bit threshold is 10.

6. 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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