TWI761850B - Bus control method and system thereof - Google Patents

Abstract

A bus control method applied to a bus connected to a master device and a plurality of slave devices is disclosed. The bus control method includes steps of: setting an arbitration value and different baud rates to the plurality of slave devices, and storing the arbitration value, and information of baud rates set in the plurality of slave devices in the master device; in the master device, selecting one, which is to be communicated, of the plurality of slave devices, and modulating the arbitration value according to the baud rate of the selected slave device, and transmitting the modulated arbitration value through the bus; in each of the plurality of slave devices, receiving the modulated arbitration value, and using the set baud rate to demodulate the modulated arbitration value, wherein the slave device correctly demodulating the arbitration value response to the master device.

Description

Busbar control method and system thereof

The present invention relates to a control method and system thereof, in particular, to a busbar control method and system under multi-channel transmission of asynchronous serial signals.

Generally, asynchronous serial transmission specifications are mostly set to one-to-one transmission (as shown in Figure 1). In addition, because the bus cannot be shared, the lines are relatively complicated and expensive (as shown in Figure 2). In addition, some systems use a ring structure for transmission. Although it can reduce the hardware and wire requirements, it has the shortcomings of data transmission delay and the damage of a single component will cause the entire system to shut down (as shown in Figure 3). Therefore, the present invention proposes a A feasible solution can be applied to the busbar structure, so that all components can be connected to a busbar at the same time, which can reduce the demand for components and wires at the same time, and also reduce the difficulty of debugging when a single component is damaged. The packet delay and single component damage caused by the ring transmission is the disadvantage that the entire system is shut down.

Therefore, in order to solve the above-mentioned problems, the purpose of the present invention is to provide a bus control method and a system thereof. There is only one slave device with the same baud rate to obtain the bus of the transmission channel, and the only arbitration use right , used to form the signal transfer between the master device and only one selected slave device. The channel arbitration usage right can also be specifically applied to a Universal Asynchronous Receiver/Transmitter (UART).

The technical means adopted by the present invention to solve the problems of the prior art is to provide a busbar control method for connecting a busbar of a master control device and a plurality of slave devices, the busbar control method comprising: A plurality of slave devices set an arbitration value and different baud rates, and the master control device stores the arbitration value and the information of the baud rate set by the plurality of slave devices; in the master control device, from the plurality of A slave device to be communicated is selected from the slave devices, and the arbitration value is modulated with the baud rate of the selected slave device, and the modulated arbitration value is sent to the bus; and in each of the A plurality of slave devices receive the modulated arbitration value through the bus, and respectively use the set baud rate to demodulate the modulated arbitration value, wherein the correct arbitration value is obtained by demodulation The slave of the value responds to the master.

In an embodiment of the present invention, a method for controlling a bus bar is provided, wherein the step of using a first signal transmission line and a second signal transmission line formed by the bus bar to connect the master device and the plurality of slave devices includes: : use the first signal transmission line to electrically connect the transmitter of the master device and the receiver of the slave device; and use the second signal transmission line to electrically connect the receiver of the master device and the transmitter of the slave device .

In an embodiment of the present invention, a method for controlling a bus bar is provided, further comprising the following steps: the master device transmits a stop signal to the selected slave device via the bus bar; the slave device and the master device The control device stops transmitting and receiving signals; then, the master control device reselects a slave device to communicate with from the plurality of slave devices, and modulates the arbitration value with the baud rate of the selected slave device , transmit the modulated arbitration value to the bus; at each of the plurality of slave devices, receive the modulated arbitration value through the bus, and respectively use the set baud rate to modulate the modulated value The arbitration value is demodulated, wherein the slave device that demodulates the correct arbitration value retrieves the master device.

In an embodiment of the present invention, a method for controlling a bus bar is provided, wherein the transmission type of the stop signal is used to stop the transmission and reception of signals between the slave device and the master device, and the bus bar is used The first signal transmission line of the master device, through the transmitter of the master device, transmits a frame that keeps the low level at least longer than the time that the receivers of the plurality of slave devices can receive the longest frame. Enter the transmission type of the abort signal.

In an embodiment of the present invention, a bus control method is provided, wherein the receiver and the transmitter are universal asynchronous receivers and transmitters (Universal Asynchronous Receiver/Transmitter, UART). The type of the baud rate is composed of single or multiple packets.

The technical means adopted by the present invention to solve the problems of the prior art is to provide a bus control system, which obtains the use right of transmission for transmitting asynchronous serial signals, comprising: a bus, a plurality of slave devices, and a master control device. The plurality of slave devices are electrically connected to the bus bar, and the slave devices have a set arbitration value and different baud rates; and the master control device is electrically connected to the bus bar, and the master control device stores the arbitration value , and the information of the baud rate set by the plurality of slave devices, the master device has a modulation module, the modulation module selects a slave device to be communicated from the plurality of slave devices, and uses The baud rate of the selected slave device modulates the arbitration value, and transmits the modulated arbitration value to the bus; wherein each of the plurality of slave devices receives the modulated value through the bus For the arbitration value, the slave device has a demodulation module, and the demodulation module uses the set baud rate to demodulate the modulated arbitration value, wherein the correct one is obtained by demodulation. The slave device of the arbitration value responds to the master device.

In an embodiment of the present invention, a busbar control system is provided, wherein the busbar includes: a first signal transmission line electrically connected to the transmitter of the master control device and the slave a receiver of the slave device; and a second signal transmission line electrically connecting the receiver of the master device and the transmitter of the slave device.

In an embodiment of the present invention, a bus control system is provided, wherein the master device has a reset module, which transmits a stop signal to the selected slave device, and stops the transmission of the slave device and the master device. And receive the signal to regain the right to use the bus.

In an embodiment of the present invention, a bus control system is provided, wherein the transmission mode of the stop signal of the reset module is that the first signal transmission line of the bus passes through the transmitter of the main control device, The time of transmitting a frame to keep the low level is at least longer than the longest time that can be received by the receivers of the plurality of slave devices, and then entering the transmission mode of the abort signal of the reset module.

RX: Receiver

TX: Transmitter

10: Busbar

11: Main control device

12: Slave device

13: The first signal transmission line

14: The second signal transmission line

Start: start bit

Stop: stop bit

PAR: parity check bit

D0~D7: data bits

ID1: First slave device

ID2: Second slave device

ID3: Third slave device

ID4: Fourth slave device

DATA1~DATAn: The first data bit ~ the nth data bit

T1: Session 1

T2: Session 2

T3: Session 3

T4: Session 4

T5: Session 5

FIG. 1 is a schematic diagram of a point-to-point transmission signal in the prior art.

FIG. 2 is a schematic diagram of the prior art star and mesh network transmission signals.

FIG. 3 is a schematic diagram of a ring network transmission signal in the prior art.

FIG. 4 shows a schematic diagram of transmission signals of a bus control method and a system thereof according to an embodiment of the present invention.

FIG. 5 shows a schematic diagram of a stop command of a busbar control method and a system thereof according to an embodiment of the present invention.

FIG. 6 shows a schematic diagram of a bus control method and a system thereof according to an embodiment of the present invention, without parity bits and with parity bits.

FIG. 7 shows a schematic diagram of a control method and a system thereof according to an embodiment of the present invention. The second slave device (ID2) responds to the master device and obtains a unique bus usage right through the master device.

FIG. 8 shows a bus control method and system according to an embodiment of the present invention. The third slave device (ID3) responds to the master device and obtains a unique bus use right through the master device.

FIG. 9 shows a bus control method and a system thereof according to an embodiment of the present invention, using abort command to generate and re-select a slave device to be communicated, so as to respond to the master device and obtain a unique bus through the master device Diagram of usage rights.

FIG. 10 shows a step diagram of a busbar control method according to an embodiment of the present invention.

FIG. 11 shows a step diagram of a busbar control method according to an embodiment of the present invention.

FIG. 12 shows a step diagram of a busbar control method according to an embodiment of the present invention.

Embodiments of the present invention will be described below with reference to FIGS. 4 to 12 . This description is not intended to limit the embodiments of the present invention, but is an example of the present invention.

As shown in FIG. 4 and FIG. 10, an embodiment of the present invention provides a bus control method, wherein a bus 10 for connecting a master device 11 and a plurality of slave devices 12 is used, the bus 10. The control method includes: Step 101: respectively setting an arbitration value and different baud rates to the plurality of slave devices 12, and storing the arbitration value and the plurality of slave devices in the master control device 11 The information of the baud rate set by the slave device 12; Step 102: In the master control device 11, select a slave device 12 to be communicated with from the plurality of slave devices 12, and use the selected slave device 12. The baud rate modulates the arbitration value, and transmits the modulated arbitration value to the bus 10 ; and Step 103 : at each of the plurality of slave devices 12 , receives the modulated arbitration value through the bus 10 . Arbitration value, and respectively use the set baud rate to demodulate the modulated arbitration value, wherein the slave device 12 that demodulates the correct arbitration value responds to the master device 11 via The main control device 11 obtains the right to use the bus bar 10 .

As shown in Fig. 4, Fig. 7 and Fig. 8, the baud rate (K bits)/second of the commonly used bus bar 10 is 300, 1200, 2400, 9600, 19200, 115200 (K bits)/second. The receiver and the transmitter are universal asynchronous receivers and transmitters (Universal Asynchronous Receiver/Transmitter, UART). The type of the baud rate is composed of single or multiple packets.

As shown in FIG. 4 and FIG. 11, an embodiment of the present invention provides a method and system for controlling the bus bar 10, wherein, step 201: use a first signal transmission line 13 to electrically connect the main control device 11 The transmitter and the receiver of the slave device 12 ; and Step 202 : use a second signal transmission line 14 to transmit and electrically connect the receiver of the master device 11 and the transmitter of the slave device 12 . Using a specific baud rate through the bus bar 10, among a plurality of transmission signal channels, select a channel with only one specific transmission signal to transmit the asynchronous serial signal. In FIG. 4, a main The control device 11 is electrically connected to a bus bar 10, and a first signal transmission line 13 and a second signal transmission line 14 are used to form the bus bar 10 for dual-signal transmission, wherein the first signal transmission line 13 is electrically connected to the main controller The transmitter TX of the device 11 and the receiver RX of the slave device 12 are connected, and the second signal transmission line 14 is electrically connected to the connection of the master device 11 . The receiver RX and the transmitter TX connected to the slave device 12 . Setting the unique channel selection baud rate is to use at least two slave devices 12 to electrically connect the bus bar 10 to form a plurality of channels for transmitting asynchronous serial signals. In order to avoid a plurality of slave devices 12 sharing the bus bar 10, signal conflict when a plurality of slave devices 12 transmit signals at the same time, therefore, the receiver RX of each of the slave devices 12 is respectively set to receive only the specially selected and unique receiver RX. Asynchronous serial signals with a Baud rate, when the receiver RX of each slave device 12 receives a uniquely selected Baud rate that is not the same, no simultaneous transmission signals will be generated. signal conflict. In the present invention, each of the plurality of slave devices 12 receives the modulated arbitration value via the bus 10, and uses the set baud rate to demodulate the modulated arbitration value. A unique baud rate is selected. Therefore, the slave device 12 that modulates the correct arbitration value through demodulation responds to the master device 11, and obtains the use right of the bus 10 through the master device 11. The only right to use is to avoid signal conflicts when transmitting signals. As shown in FIG. 4 , in the master device 11 , a slave device 12 to be communicated is selected from the plurality of slave devices 12 , and the arbitration value is modulated by the baud rate of the selected slave device 12 , to transmit the modulated arbitration value to the bus 10, using the transmitter TX of the master control device 11 to transmit the modulated signal of the arbitration value to the first signal transmission line 13 of the bus 10, when After the receivers RX of all the slave devices 12 receive the modulated signals of the arbitration value, only one of the slave devices 12 demodulates the correct arbitration value, and responds to the master device 11 through the master The device 11 obtains the right to use the bus 10 , and the other slave devices 12 demodulate the incorrect arbitration value and cannot respond to the master device 11 , so the master device 11 cannot obtain the right to use the bus 10 .

As shown in FIGS. 4 and 7, a plurality of slave devices 12 are connected to the bus bar 10, and the slave devices 12 include a first slave device (ID1), a second slave device (ID2), and a third slave device (ID3), the fourth slave device (ID4). The master device 11 transmits the modulated arbitration value to the bus 10, the receiver (RX) of each slave device (12) receives the demodulated signal of the arbitration value, each of the slave devices (12) Demodulate the correct arbitration value, and respond to the master control device 11. The use rights of the bus bar 10 obtained through the master control device 11 are not the same. If the first slave device (ID1) has the first The selected channel baud rate (Baud rate 1) is 2400 (K bits)/second, the second channel selected baud rate (Baud rate 2) of the second slave device (ID2) is 1600 (K bits)/second, the third channel selected baud rate (Baud rate 2) is 1600 (K bits)/second The third channel selection baud rate (Baud rate 3) of the slave device (ID3) is 1200 (K bits)/sec. In the master device 11, the second slave device to be communicated is selected from the plurality of slave devices 12 The second channel baud rate (Baud rate2) of (ID2) is 1600 (K bits)/sec, and the second channel baud rate (Baud rate2) of the selected slave device 12 is 1600 (K bits) )/sec to modulate the arbitration value, and transmit the modulated arbitration value to the bus 10, then, for each of the plurality of slave devices 12, a first slave device (ID1), a second slave device (ID2), the third slave device (ID3), and the fourth slave device (ID4), the baud rate (Baud rate2) of the second channel selection received via the bus 10 is 1600 (K bits)/sec for the The arbitration value is modulated by the arbitration value, and respectively uses the set baud rate to demodulate the modulated arbitration value, wherein the second slave device (ID2) modulates the correct arbitration value by demodulation In response to the master control device 11 , the use right of the bus bar 10 is obtained through the master control device 11 . The second channel selection baud rate (Baud rate2) by the second slave device (ID2) is 1600 (K bits)/sec, different from other transmission baud rates (Baud rate), 2400 (K bits)/sec, 1200 (K bits)/sec, so the second slave device ( ID2 ) responds to the master device 11 and obtains a unique and specific arbitration use right through the master device 11 . In the present invention, a unique slave device 12 is selected and set in the shared bus bar 10 to perform signal transmission with the master device 11 under the modulation and demodulation of different baud rates.

As shown in Fig. 4, Fig. 5, Fig. 7, Fig. 8, Fig. 9, Fig. 11 and Fig. 12, in an embodiment of the present invention, a method for controlling a bus bar 10 and a system thereof are provided, The slave device 12 responds to the master device 11 again, and obtains the bus bar 10 through the master device 11 The steps of obtaining the right to use include: Step 301 : the master device 11 transmits a stop signal to the selected slave device 12 via the bus 10 ; Step 302 : the slave device 12 and the master device 11 Stop transmitting and receiving signals; Step 303 : In the master device 11 , re-select a slave device 12 to be communicated with from the plurality of slave devices 12 , and use the baud rate of the selected slave device 12 to communicate with the slave device 12 . The arbitration value is modulated, and the modulated arbitration value is sent to the bus 10 ; and Step 304 : at each of the plurality of slave devices 12 , the modulated arbitration value is received via the bus 10 , and respectively use the set baud rate to demodulate the modulated arbitration value, wherein the slave device 12 that obtains the correct arbitration value by demodulation responds to the master control device 11 via the master control device 11 Obtain the right to use the bus bar 10 . As shown in FIG. 11 , the step of re-selecting the arbitration use right of a specific channel is generated by using a break command, and the break command is transmitted through the first signal transmission line 13 using the transmitter TX of the master control device 11 . ) to the receivers RX of the plurality of slave devices 12, after each of the plurality of the slave devices 12 determines that the abort command is received, the transmitters TX of the plurality of the slave devices 12 stop transmitting asynchronous serial signals to the master The receiver RX of the control device 11. Then, the master control device 11 is responded to again, and the master control device 11 obtains the arbitration use right of a specific transmission channel. After the receivers RX of a plurality of the slave devices 12, the master device 11 is re-selected from the plurality of slave devices 12 to select a slave device 12 to be communicated, for example, a third slave device (ID3) to be communicated is selected. , and modulate the arbitration value with the baud rate 1200 (K bits)/sec of the selected third slave device (ID3), and transmit the modulated arbitration value to the bus 10, Fig. 4 , as shown in FIG. 11, the modulated arbitration value is sent to the receiver RX of the slave device 12 via the first signal transmission line 13 of the bus bar 10. The slave device 12 has a first slave device (ID1), a second slave device device (ID2), third slave device (ID3), fourth slave device (ID4). In each of the plurality of slave devices 12, the arbitration value modulated by the baud rate 1200 (K bits)/sec of the third slave device (ID3) is received via the bus 10, and the arbitration value is respectively used The baud rate set to the The overmodulated arbitration value is demodulated. The first channel selection baud rate (Baud rate 1) of the first slave device (ID1) is 2400 (K bits)/sec. The second slave device ( The second channel selected baud rate (Baud rate 2) of ID2) is 1600 (K bits)/sec for demodulation, and the third channel selected baud rate (Baud rate 3) of the third slave device (ID3) is demodulated The variable is 1200 (K bits)/second, and the correct arbitration value transformed by demodulation is 1200 (K bits)/second of the third selected channel baud rate (Baud rate 3), so the third slave device ( ID3) responds to the master control device 11, and obtains the use right of the bus bar 10 through the master control device 11. The rest of the first slave device (ID1) and the second slave device (ID2) demodulate the incorrect arbitration value and cannot respond to the master device 11. Therefore, the first slave device ( ID1), the right to use the bus 10 of the second slave device (ID2). As shown in Figure 11, the correct arbitration value obtained by demodulation is 1200 (K bits)/sec of the third channel selection baud rate (Baud rate 3), and the retransmission of the asynchronous serial signal is the first data bit Element DATA1~nth data bit DATAn, data bits D0~D7. The master control device 11 of the present invention has a reset module, which transmits a stop signal to the selected slave device 12, and the slave device 12 and the master control device 11 stop transmitting and receiving signals for re-acquiring the bus bar 10 Rights of Use.

As shown in FIG. 9 , the first time period T1 is when the transmitter (TX) of the master device 11 transmits a stop signal generated by a stop command to the bus bar 10 , and the second time period T2 is when all the slave devices 12 connected to the bus bar 10 are After receiving the abort signal of the abort command, stop transmitting the signal to the bus bar 10. The third time period T3 is when the third slave device (ID3) obtains the right to use the bus bar 10, and the remaining first slave device (ID1), the second slave device (ID1), the second slave device The device (ID2) demodulates the incorrect arbitration value and cannot obtain the right to use the bus bar 10. Therefore, the demodulation converts the correct arbitration value to be 1200 (Baud rate 3). K bits)/sec, retransmit the asynchronous serial signal, which is the first data bit DATA1 ~ the nth data bit DATAn, and finally reset the module 15 (not shown) and then transmit the abort signal generated by the abort command to bus bar 10. The fourth period T4 is when all the slave devices 12 connected to the bus bar 10 receive the abort signal of the abort command and stop transmitting signals to the bus bar 10 , and the fifth period T5 is when the first slave device (ID1) obtains the use of the bus bar 10 right, the remaining second slave (ID2), the third slave device (ID3) demodulates the incorrect arbitration value and cannot obtain the right to use the bus 10, so the correct arbitration value obtained by demodulation is the first channel baud rate ( Baud rate 1) is 2400 (K bits)/sec, and the asynchronous serial signal is retransmitted, which is the first data bit DATA1 to the nth data bit DATAn.

As shown in FIG. 4 , FIG. 5 , and FIG. 11 , in an embodiment of the present invention, a method for controlling a bus bar 10 and a system thereof are provided, wherein the slave device 12 and the master device 11 stop transmitting and receiving The signal, through a transmission type of a stop signal, is transmitted by the first signal transmission line 13 of the bus bar 10 through the transmitter of the master device 11, and the time for a frame to maintain a low level is at least longer than the transmission of a plurality of the slaves. The receiver of the device 12 enters the transmission mode of the abort signal of the reset module 15 (not shown) after receiving the longest frame time. As shown in Figure 5, from top to bottom are the standard stop signal baud rates. The stop bit (stop bit) of the digital logic high level is normally 1. When the stop command is generated, the stop bit Stop is from 1 to 0. As shown in Figure 5, from top to bottom, there are two stop signals with a faster transmission baud rate. The bottom layer is a stop signal with the slowest transmission baud rate. The stop bit Stop is greater than the transmission complex number. Among the receivers of the slave device 12, the longest one frame time can be received, so it enters the transmission mode of the abort signal. Among them, the two stop signals with a faster baud rate, the stop bit Stop with a faster baud rate, and the time of transmitting a frame to keep the low level are less than the receivers that transmit a plurality of the slave devices 12 can accept. The time of the longest frame, so it cannot enter the transmission mode of the abort signal of the reset module (not shown).

As shown in FIG. 6, the transmitter TX of the main control device 11 transmits the frame with the low level of the digital logic as the start bit, then transmits at least one data bit, and finally at least one digital bit Logic high level stop bit Stop, the parity bit There is a direct connection between PAR (data bit) and the stop bit Stop for transmission/or a parity check bit PAR (parity check bit) between the data bit and the stop bit Stop.

As shown in FIG. 4 and FIG. 9, in an embodiment of the present invention, a method and system for controlling the bus bar 10 are provided, wherein when there is only one slave device 12, the correct one is converted by demodulation. The slave device 12 of the arbitration value obtains the use right of the bus 10, and the transmitter TX of the other slave devices 12 that cannot obtain the use right of the specific bus 10 only enters the state of listening (LISTEN) the asynchronous serial signal , instead of entering the state of receiving the asynchronous serial signal, the receiver RX of the slave device 12 that cannot obtain the arbitration use right of the specified channel in the state of listening (LISTEN) the asynchronous serial signal stops passing through the second The signal transmission line 14 receives the asynchronous serial signal transmitted from the transmitter TX of the master device 11 . In addition, in the state of listening (LISTEN) the asynchronous serial signal, only after listening (LISTEN) the abort command, enter the use abort command to generate the arbitration use right to re-select the specific channel.

The above description and description according to an embodiment of the present invention are only the description of the preferred embodiment of the present invention, and those with ordinary knowledge in the art can make other claims based on the scope of the patent application defined below and the above description. Modifications, but these modifications should still be within the scope of the right of the present invention for the inventive spirit of the present invention.

RX: Receiver

TX: Transmitter

10: Busbar

11: Main control device

12: Slave device

13: The first signal transmission line

14: The second signal transmission line

ID1: First slave device

ID2: Second slave device

ID3: Third slave device

ID4: Fourth slave device

Claims (10)

A busbar control method is used to connect a busbar of a master control device and a plurality of slave devices, the busbar control method comprising: respectively setting an arbitration value and a different baud rate to the plurality of slave devices, and The master device stores the arbitration value and the information of the baud rate set by the plurality of slave devices; in the master device, a slave device to be communicated is selected from the plurality of slave devices, and the selected slave device is used The baud rate of the slave device modulates the arbitration value, and transmits the modulated arbitration value to the bus; and at each of the plurality of slave devices, receives the modulated arbitration value through the bus , and respectively use the set baud rate to demodulate the modulated arbitration value, wherein the slave device that obtains the correct arbitration value by demodulation responds to the master device. The bus control method as claimed in claim 1, wherein the step of using a first signal transmission line and a second signal transmission line formed by the bus to connect the master device and the plurality of slave devices includes: using the first signal transmission line and the second signal transmission line. A signal transmission line is electrically connected to the transmitter of the master device and the receivers of the plurality of slave devices; and the second signal transmission line is used to electrically connect the receiver of the master device and the transmitter of the plurality of slave devices . The bus control method according to claim 1, further comprising: sending a stop signal to the selected one of the bus bars from the master control device Slave device; stop transmitting and receiving signals at the slave device and the master device; then at the master device, reselect a slave device to be communicated with from the plurality of slave devices, and use the selected slave device as a slave device. The baud rate modulates the arbitration value, and transmits the modulated arbitration value to the bus; and each of the plurality of slave devices receives the modulated arbitration value through the bus, and respectively The modulated arbitration value is demodulated by using the set baud rate, wherein the slave device that obtains the correct arbitration value by demodulation responds to the master device. The bus control method according to claim 3, wherein the step of using the stop signal to stop the slave device and the master device from transmitting and receiving signals further comprises: using a first signal transmission line of the bus through the A transmitter of the master device keeps the low level for a period of time during which a frame is transmitted, which is at least longer than the longest period of a frame that can be received by the receivers of the plurality of slave devices. The bus control method according to claim 2, wherein the receiver and the transmitter are universal asynchronous receiver and transmitter (Universal Asynchronous Receiver/Transmitter, UART). The bus control method according to claim 2, wherein the type of the baud rate is composed of single or multiple packets. A busbar control system, which obtains the use right of transmission and is used to transmit asynchronous serial signals, comprising: a busbar; a plurality of slave devices electrically connected to the bus bar, the slave devices having an arbitration value and different baud rates set; and a master control device electrically connected to the bus bar, the master control device storing the arbitration value, and The information of the baud rate set by the plurality of slave devices, the master device has a modulation module, the modulation module selects a slave device to be communicated from the plurality of slave devices, and uses the selected The baud rate of the slave device modulates the arbitration value, and transmits the modulated arbitration value to the bus; wherein each of the plurality of slave devices receives the modulated arbitration value via the bus value, the slave device has a demodulation conversion module, the demodulation conversion module uses the set baud rate to demodulate the modulated arbitration value, wherein the correct arbitration value is obtained by demodulation The slave of the value responds to the master. The bus control system of claim 7, wherein the bus comprises: a first signal transmission line electrically connected to the transmitter of the master control device and the receivers of the plurality of slave devices; and a second signal transmission line to transmit The receiver of the master device and the transmitter of the plurality of slave devices are electrically connected. The bus control system of claim 8, wherein the master device has a reset module that transmits a stop signal to the selected slave device, and the slave device and the master device stop transmitting and receiving signals, To regain the right to use the bus. The bus control system as claimed in claim 9, wherein the reset module transmits a frame for the time of keeping the low level through the first signal transmission line of the bus and the transmitter of the master device, and the at least longer than the receiver transmitting multiples of this slave can accept the longest of one frame of time.

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