KR101877332B1 - Method for preventing collision packet in communication system supporting multi-protocol - Google Patents

Abstract

The present invention relates to a method for preventing packet collisions in a communication system supporting multiple protocols, and more particularly, to a slave device using a specific protocol, . A method for preventing a packet collision in a communication system having a plurality of slave devices connected to a master device and a plurality of slave devices connected in a multi-drop manner, includes the steps of: transmitting an isolation packet to a specific slave device; Receiving the command packet from the master device after receiving the quarantine packet from the master device, and not receiving or discarding the command packet when the command packet is transmitted from the master device.

Description

[0001] METHOD FOR PREVENTING COLLISION PACKET IN COMMUNICATION SYSTEM SUPPORTING MULTI-PROTOCOL [0002]

The present invention relates to a method for preventing packet collisions in a communication system supporting multiple protocols, and more particularly, to a slave device using a specific protocol, .

In the multi-drop communication system, the master device and the slave device responding to the request of the master device are connected by a single line. Each slave device has a unique ID for identification. The master device requests data to a specific slave device based on the unique ID, and the specific slave device to which the data is requested can transmit data through the line.

At this time, the master device and the slave device must generate and transmit a packet according to a protocol promised to transmit data and request data. Sometimes, a wrong packet is recognized as a normal packet and the slave device malfunctions.

A method of inspecting a packet by adding an inspection field to an existing packet has been developed so that an erroneous packet is not recognized as a normal packet. Typically, there are a CRC method and a CHECK SUM method.

However, when there are a plurality of different protocols in the multi-drop communication system, the error packet distinguishing ability of the CRC method and the CHECK SUM method is remarkably reduced and collision between packets frequently occurs. Furthermore, when the slave device is driven, the driving device is driven by recognizing the error packet as a normal packet, and a major accident such as a collision with another driving device has occurred.

Therefore, there is a demand for a method capable of preventing impulse between packets in a multi-drop communication system using a plurality of protocols.

The present invention provides a method for preventing impulse between packets in a multi-drop communication system using a plurality of technical protocols to be achieved by the present invention.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not intended to limit the invention to the precise form disclosed. There will be.

According to an aspect of the present invention, there is provided a method of preventing packet collisions in a communication system supporting multiple protocols.

A packet collision avoiding method of a communication system having a master device and a plurality of slave devices connected by a multi-drop method and using different protocols is characterized in that the master device transmits a quarantine packet to a specific slave device, And if the command packet is transmitted from the master device after receiving the isolation packet from the device, the command packet may not be received, or may be received and discarded.

In the present invention, the step of transmitting a quarantine packet may be a step of transmitting a quarantine packet to a slave device using a specific protocol.

In the present invention, the step of not receiving the command packet or discarding the command packet may be a step of not receiving or discarding the command packet transmitted from the master device for a preset time.

In the present invention, the step of not receiving the command packet or discarding the command packet may be a step of not receiving or discarding a command packet less than a predetermined number of bytes transmitted from the master device.

In the present invention, it is preferable that the master device transmits an isolation release packet to a specific slave device, and when the specific slave device receives the command packet from the master device after receiving the isolation release packet from the master device, And executing the command packet.

In the present invention, the isolation packet can be designed differently for each protocol.

In the present invention, the instruction packet can be generated by checking the address of the value to be controlled through the control table of each slave device, and referring to the ID and the address.

In the present invention, each slave device may be an actuator driven by a master device.

According to the embodiment of the present invention, since the master device can control the slave devices having a specific protocol in the multi-protocol environment to not execute the command packet, it is possible to minimize the possibility that the slave device can recognize an erroneous packet as a normal packet can do. That is, the user can use the communication system having a plurality of protocols more safely.

It should be understood that the effects of the present invention are not limited to the above effects and include all effects that can be deduced from the detailed description of the present invention or the configuration of the invention described in the claims.

1 is a diagram showing a configuration of a communication system according to an embodiment of the present invention.
2 is a diagram illustrating a configuration of a communication system to which a user terminal is added according to an embodiment of the present invention.
3 is a flowchart illustrating a packet collision avoidance method in a communication system according to an embodiment of the present invention.
4 is a flowchart illustrating a packet collision avoidance method in a communication system according to another embodiment of the present invention.
5 is a flowchart illustrating a packet collision avoidance method in a communication system according to another embodiment of the present invention.
FIG. 6 shows a control table for explaining a method of generating a command packet in a communication system to which the present invention is applied.
7 shows an output curve according to a position error of a slave device to which the present invention is applied.
FIG. 8 shows a target position to which a slave device to which the present invention is applied moves.
FIG. 9 shows a data valid area that can be recorded by the user in the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and similar parts are denoted by like reference characters throughout the specification.

Throughout the specification, when a part is referred to as being "connected" (connected, connected, coupled) with another part, it is not only the case where it is "directly connected" "Is included. Also, when an element is referred to as " comprising ", it means that it can include other elements, not excluding other elements unless specifically stated otherwise.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In this specification, the terms "comprises" or "having" and the like refer to the presence of stated features, integers, steps, operations, elements, components, or combinations thereof, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a diagram showing a configuration of a communication system 1 according to an embodiment of the present invention.

The communication system 1 according to the embodiment of the present invention connects one master device 10, N slave devices 20, master device 10 and slave device 20 in a multi-drop manner And a communication bus 30 for transmitting and receiving packets. At this time, the master device 10 and the slave device 20 communicate with each other while exchanging packets through the communication bus 30. The types of packets include a command packet transmitted from the master device 10 to the slave device 20 to control the slave device 20 and a status packet transmitted from the slave device 20 to the master device 10. At this time, the status packet is generated in response to the command packet, and can be generated only when the slave device 20 executes the command packet received from the master device 10. [

The slave device 20 has a unique ID for identification, and the master device 10 generates and transmits a command packet based on the unique ID. Accordingly, only the slave device 20 having the unique ID performs the command packet and transmits the status packet.

2 is a diagram illustrating a configuration of a communication system to which a user terminal is added according to an embodiment of the present invention. The slave device 20 of the present invention is controlled by a command packet of the master device 10 and the master device 10 is again connected to a user terminal such as a PC or a wired or wireless remote controller.

At this time, if the user inputs a signal (hereinafter, control signal) for controlling each slave device 20 through the user terminal, the control signal from the user terminal is transmitted to the master device 10 via a communication bus of, for example, And the master device 10 converts the control signal into a command packet of RS485 type suitable for control of the slave device 20 and transmits it to each or all of the slave devices 20 by a multi-drop method.

FIG. 3 is a flowchart showing a packet collision avoiding method of the communication system 1 according to an embodiment of the present invention, and each step will be described focusing on the slave device 20.

In step S100, the slave device 20 waits for the reception of the isolation packet transmitted from the master device 10. [ The isolation packet is a packet generated by the master device 10 in order to isolate at least one slave device 20 or a specific slave device 20 using a specific protocol and is generated by the slave device 10 20). At this time, the isolation packet may be designed differently according to the protocol. In step S100, the slave device 20 can not occupy the communication bus in a state of waiting for reception of the isolation packet from the master device 10, and can receive only the packet transmitted by the master device 10. [

In step S110, the slave device 20 determines whether a quarantine packet is received from the master device 10 via the communication bus 30. At this time, the isolation packet is a packet generated by the master device 10 to isolate at least one slave device 20 or a specific slave device 20 using a specific protocol. The isolation packet is generated by the master device 10, May be transmitted to the device (20). The slave device 20 receiving the quarantine packet does not receive the command packet transmitted from the master device 10 after the quarantine packet or discards it after receiving it. At this time, the isolation packet may be designed differently according to the protocol.

If the slave device 20 determines that a quarantine packet has been received from the master device 10, the slave device 20 determines whether a command packet is transmitted from the master device 10 in step S120.

The command packet is a bundle of data. The command packet is generated by the master device 10 by attaching a header indicating the ID of the slave device 20 to which the command packet is to be transmitted, by dividing the data to be transmitted to a predetermined size. The configuration of the command packet will be described in detail below. At this time, if the slave device 20 does not receive the command packet from the master device 10, it can not occupy the communication bus 30 and can not transmit the status packet. That is, the slave device 20 receiving the command packet can occupy the communication bus 30 for a limited time and transmit the status packet. At this time, the status packet may be generated by the slave device 20 as a packet corresponding to the command packet, and may contain information that the command packet has been normally executed.

If the slave device 20 determines in step S120 that the command packet has been transmitted from the master device 10, the slave device 20 does not receive the command packet transmitted in step S130, or discards it after receiving the command packet.

According to the embodiment of the present invention, the slave device 20 determines whether the quarantine release packet is received from the master device 10 via the communication bus in step S140, and if it is determined that the quarantine release packet has been received, It is determined whether a command packet has been received from the master device 10. [

If the slave device 20 determines that the command packet has been received in step S150, it executes the command packet in step S160. That is, the slave device 20 receiving the quarantine packet from the master device 10 may not receive all the command packets transmitted from the master device 10 until receiving the quarantine release packet, or may discard them after receiving the command packet.

Although not shown in FIG. 3, the slave device 20 receiving the command packet can occupy the communication bus 30 for a limited time and transmit the status packet to the master device 10.

If the slave device 20 determines in step S110 that a quarantine packet has not been received from the master device 10 via the communication bus 30, the slave device 20 determines whether an instruction packet is received from the master device 10 in step S150 .

If it is determined in step S120 that the command packet has not been transmitted from the master device 10, the slave device 20 determines whether the quarantine release packet is received from the master device 10 in step S140.

If the slave device 20 determines in step S140 that the quarantine release packet has not been received from the master device 10, the process returns to step S120 and determines whether or not the command packet is transmitted from the master device 10. [

FIG. 4 is a flowchart illustrating a method of preventing packet collisions in a communication system according to another embodiment of the present invention. Each step will be described focusing on a slave device 20.

In step S200, the slave device 20 waits for the reception of the isolation packet transmitted from the master device 10. [ The isolation packet is a packet generated by the master device 10 in order to isolate at least one slave device 20 or a specific slave device 20 using a specific protocol and is generated by the slave device 10 20). At this time, the isolation packet may be designed differently according to the protocol. In step S200, the slave device 20 can not occupy the communication bus in a state of waiting for reception of the isolation packet from the master device 10, and can receive only the packet transmitted by the master device 10. [

In step S210, the slave device 20 determines whether a quarantine packet is received from the master device 10 via the communication bus 30. [ At this time, the isolation packet is a packet generated by the master device 10 to isolate at least one slave device 20 or a specific slave device 20 using a specific protocol. The isolation packet is generated by the master device 10, May be transmitted to the device (20). When the command packet transmitted from the master device 10 does not satisfy the predetermined condition, the slave device 20 receiving the isolation packet does not receive the command packet or discards it after receiving the command packet. At this time, the isolation packet may be designed differently according to the protocol.

In another embodiment of the present invention, the predetermined condition is the number of bytes of the command packet, and the slave device 20 determines whether a command packet has been transmitted from the master device 10 in step S220. The command packet is a bundle of data. The command packet is generated by the master device 10 by attaching a header indicating the ID of the slave device 20 to which the command packet is to be transmitted, by dividing the data to be transmitted to a predetermined size. At this time, if the slave device 20 does not receive the command packet from the master device 10, it can not occupy the communication bus 30 and can not transmit the status packet. That is, the slave device 20 receiving the command packet can occupy the communication bus 30 for a limited time and transmit the status packet. At this time, the status packet may be generated by the slave device 20 as a packet corresponding to the command packet, and may contain information that the command packet has been normally executed.

If it is determined in step S220 that the command packet has been transmitted, the slave device 20 determines whether the number of bytes of the command packet transmitted in step S230 exceeds the preset number of bytes. If it is determined that the number of bytes of the command packet exceeds the predetermined number of bytes, the slave device 20 executes the command packet in step S240. If it is determined that the command packet is equal to or less than the preset number of bytes, Do not do or discard after receipt.

Although not shown in FIG. 4, the slave device 20 receiving the command packet can occupy the communication bus 30 for a limited time and transmit the status packet to the master device 10.

The method may further include a step S250 of determining whether the slave device 20 does not transmit a command packet from the master device 10 within a predetermined time according to the embodiment of the present invention. That is, in step S250, it is determined whether a command packet is further transmitted within a predetermined time period. When the command packet is transmitted from the master device 10, the slave device 20 returns to step S230, It is determined whether the packet is a command packet equal to or less than a predetermined number of bytes. If the command packet is not transmitted from the master device 10 within the predetermined time in step S250, the slave device 20 terminates the procedure for not receiving or discarding command packets of a certain number of bytes or less

4 shows only the case where the command packet is not received or is discarded when the command packet is less than a certain number of bytes. However, it is needless to say that the command packet may be set not to be received or discarded when the command packet is more than a certain number of bytes.

FIG. 5 is a flowchart illustrating a packet collision avoiding method in a communication system according to another embodiment of the present invention, and each step will be described focusing on a slave device 20. FIG.

In step S300, the slave device 20 waits for reception of the isolation packet transmitted from the master device 10. [ The isolation packet is a packet generated by the master device 10 in order to isolate at least one slave device 20 or a specific slave device 20 using a specific protocol and is generated by the slave device 10 20). At this time, the isolation packet may be designed differently according to the protocol. The slave device 20 can not occupy the communication bus in a state of waiting for reception of the isolation packet from the master device 10 in step S300 and can only receive the packet transmitted by the master device 10. [

In step S310, the slave device 20 determines whether a quarantine packet is received from the master device 10 via the communication bus 30. When the command packet transmitted from the master device 10 does not satisfy the predetermined condition, the slave device 20 which has received the isolation packet can not receive the command packet or can discard it after receiving the command packet.

In another embodiment of the present invention, the predetermined condition is a time taken for the command packet to be transmitted after receiving the quarantine packet from the master device 10, and the slave device 20 transmits the command packet from the master device 10 in step S320, Is transmitted. The command packet is a bundle of data. The command packet is generated by the master device 10 by attaching a header indicating the ID of the slave device 20 to which the command packet is to be transmitted, by dividing the data to be transmitted to a predetermined size. At this time, if the slave device 20 does not receive the command packet from the master device 10, it can not occupy the communication bus 30 and can not transmit the status packet. That is, the slave device 20 receiving the command packet can occupy the communication bus 30 for a limited time and transmit the status packet.

At this time, the status packet may be generated by the slave device 20 as a packet corresponding to the command packet, and may contain information that the command packet has been normally executed.

If it is determined in step S320 that the command packet has been transmitted from the master device 10, the slave device 20 determines whether the time taken for the command packet to be transmitted after receiving the quarantine packet from the master device 10, Or more.

If the time taken for the command packet to be transmitted is longer than the preset time after receiving the quarantine packet, the slave device 20 executes the command packet in step S340, and the time taken for the command packet to be transmitted after receiving the quarantine packet If it is less than the preset time, the command packet is not received or discarded after receiving in step S360.

Although not shown in FIG. 5, the slave device 20 receiving the command packet can occupy the communication bus 30 temporarily and transmit the status packet to the master device 10 for a limited time.

In step S350, the host device 10 further includes step S340, step S360, and step S350 according to an embodiment of the present invention to determine whether the slave device 20 has not transmitted a command packet from the master device 10 within a predetermined time .

That is, in step S350, it is determined whether a command packet is further transmitted within a predetermined period of time. When the slave device 20 receives the command packet from the master device 10, the slave device 20 returns to step S330, After receiving the quarantine packet from the device 10, it is determined whether the time taken for the command packet to be transmitted is longer than a preset time. The slave device 20 receives the quarantine packet from the master device 10 if the command packet is not transmitted within a predetermined time from the master device 10 in step S350, Terminate the procedure of not receiving or discarding and discarding.

Using the packet collision avoidance method of the communication system according to the embodiment of the present invention, the slave device 20 can use the isolation packet that does not receive the command packet transmitted from the master device 10, The slave devices 20 having a specific protocol in the protocol environment can be set not to execute the command packet, so that it is possible to minimize the possibility that the slave device 20 recognizes an erroneous packet as a normal packet. That is, the user can use the communication system 1 having a plurality of protocols more stably.

FIG. 6 shows a control table referred to when generating the command packet of the communication system 1 according to an embodiment of the present invention.

The control table is for referring to data included in an instruction packet when the master device 10 generates a command packet for controlling the slave device 20 and is composed of data on the status and operation of the slave device. 6 to 9 illustrate an example in which the slave device 20 is a slave device (actuator) driven by the master device 10. FIG.

Writing the values in the control table drives the slave device and reads the value of the control table to grasp the state of the slave device.

The control table consists of a RAM area and an EEPROM area. The data in the RAM area is set to the initial value every time power is applied, but the data in the EEPROM area is preserved even when the power is turned off.

The control table includes items such as an address, an item, an access, and an initial value.

Here, the address means the address of the memory to read and write the value. The item indicates the type of data designated at each address. The access method indicates whether the item is recorded or readable. In addition, the initial value is the factory default value in the case of data in the EEPROM area, and the initial value in case of data in the RAM area.

Hereinafter, the meaning of data designated at each address will be described.

First, it is the EEPROM area.

0X00, 0X01: Model number

0X02: Firmware version

0X03: ID number for slave device identification. Each linked slave device must be assigned a different ID.

0X04: The baud rate that determines the communication speed. The calculation formula is "Speed [BPS] = 2000000 / [0049] Address4 + 1]".

By way of example, the data values for the major board ratios are shown in Table 1. In case of UART (Universal Asynchronous Receiver / Transmitter), communication error is less than 3%.

Address4 Setting BPS Target BPS error One 1000000.0 1000000.0 0.000% 3 500000.0 500000.0 0.000% 4 400000.0 400000.0 0.000% 7 250000.0 250000.0 0.000% 9 200000.0 200000.0 0.000% 16 117647.1 115200.0 -2.124% 34 57142.9 57600.0 0.794% 103 19230.8 19200.0 -0.0160% 207 9615.4 9600.0 -0.0160%

0X05: Return delay time, that is, the delay time until the status packet is returned after command packet transmission.

0X06, 0X07, 0X08, 0X09: Limit the operating angle. Set the angular interval in which the operation of the slave device is allowed.

0X0B: Maximum limiting temperature. Means the operating limit temperature of the slave device.

0X0C, 0X0D: lowest / highest limiting voltage. Means the upper and lower limits of the operating voltage range of the slave device.

0X0E, 0X0F: Maximum torque. This is the maximum torque output value of the slave device.

When this value is set to '0', it becomes a free run state with no torque.

Max Torque / Torque Limit is allocated to EEPROM area (0X0E, 0X0F) and RAM area (0X22, 0X23). When power is on, value of EEPROM area is copied to RAM.

The torque of the slave device is limited by the value (0X22, 0X23) located in the RAM.

0X10: Status return level. After the command packet is transmitted, it is determined whether or not the slave device returns the status packet. The value is as shown in Table 2 below. On the other hand, in the case of the command packet of the broadcast ID (0XFE), the status packet is not returned regardless of the status return level value.

Address16 Return of Status Packet 0 Do not return for all instructions One Return only for READ_DATA command 2 Return for all instructions

0X11: Alarm LED. The LED blinks when the corresponding error bit for each command is set to 1 when an error occurs. The corresponding error table for each command is shown in Table 3.

Bit function Bit 7 0 Bit 6 If set to 1, LED will flash when Instruction Error occurs. Bit 5 If set to 1, LED will blink when overload error occurs. Bit 4 If set to 1, LED blinks when Check sum error occurs Bit 3 If set to 1, the LED blinks when a Range Error occurs Bit 2 If set to 1, LED will flash when overheating error occurs. Bit 1 If set to 1, the LED will flash when an Angle Limit Error occurs. Bit 0 If set to 1, the LED blinks when an input voltage error occurs.

The function of each bit is operated by 'OR' logic.

In other words, when set to 0X05, the LED blinks even if an input voltage error occurs, and the LED blinks even if an overheating error occurs.

After returning to the normal state after an error occurs, the LED will stop blinking after 2 seconds.

0X12: Alarm shutdown. If an error occurs and the corresponding error bit for each instruction is set to 1, the slave device will torque off, or stop working. The corresponding error table for each command is shown in Table 4.

Bit function Bit 7 0 Bit 6 If set to 1, Torque Off Bit 5 If set to 1, Torque Off Bit 4 If set to 1, when Check sum error occurs Torque Off Bit 3 If set to 1, Torque Off Bit 2 If set to 1, when overheating error occurs Torque Off Bit 1 If set to 1, when Angle Limit Error occurs Torque Off Bit 0 If set to 1, Torque Off

The function of each bit is operated by 'OR' logic.

However, unlike the alarm LED, the torque off state continues even after returning to the normal state after an error has occurred.

Therefore, to exit the shutdown state, the torque enable [0X18] must be reset to 1.

0X14, 0X15, 0X16, 0X17: Calibration (Callibraion). The data can not be changed by the user to compensate the deviation between potentiometer products.

The following address is the RAM area.

0X18: Torque enable. When power is applied to the slave device in the digital mode, the free-running state in which no torque occurs occurs.

At this time, if 1 is set to address 0X18, the torque is enabled.

0X19: LED. If it is set to 1, the LED will be on; if it is set to 0, the LED will be off.

0X1A, 0X1B, 0X1C, 0X1D: compliance margin and slope. Set the margin and slope to control the actuator's compliance. A good use of compliance can have a shock-absorbing effect.

The length of A, B, C, and D in the output curve according to the position error in Fig. 7 is the compliance value.

0X1E, 0X1F: Target position. It means the position where the slave device wants to move.

In FIG. 8, if the value is set to a maximum value of 0X3ff, it moves to 300 DEG.

0X20, 0X21: Moving speed. It means the moving speed to the target position. Set to the maximum value of 0x3ff to move at 70 rpm.

For reference, when the speed is set to 1, it is the lowest speed. When it is set to 0, it moves to the maximum speed that can be obtained on the current applied voltage. That is, the speed control is not performed.

0X22, 0X23: Maximum torque. This is the maximum torque output value of the slave device. When this value is set to '0', it becomes a free run state with no torque. Max Torque / Torque Limit is allocated to EEPROM area (0X0E, 0X0F) and RAM area (0X22, 0X23). When power is on, value of EEPROM area is copied to RAM. The torque of the slave device is limited by the value (0X22, 0X23) located in the RAM.

0X24, 0X25: current position. Current position of slave device

0X26, 0X27: Current speed. Current speed of slave device

0X28, 0X29: Current load. The size of the load currently driven by the slave device. In the table below, bit 10 is the direction in which the load is applied.

0X2A: Current voltage. The voltage currently applied to the slave device. This value is 10 times the actual voltage. That is, when 10V, 100 [0X64] is read.

0X2B: Current temperature. Celsius temperature inside the slave unit.

0X2C: Registration command. It is set to 1 when the command is registered by the REG_WRITE command, and becomes 0 when the command registered by the ACTION command is completed.

0X2E: Move. It is set to 1 when the slave device is in a moving state by its own power.

0X2F: Lock. If it is set to 1, only the value of address 0X18 ~ 0X23 can be recorded, and recording in the remaining area is prohibited. Once locked, power off can be disabled.

0X30, 0X31: Punch. The minimum amount of current supplied to the motor during operation. The initial value is 0X20 and can be set up to 0X3FF.

At this time, each data has a valid range. An error is returned if a write (WRITE) instruction out of it is sent. In the table of Fig. 9, the length and range of data that can be recorded by the user are summarized. 16-bit data is indicated by two bytes, [L] and [H]. These two bytes must be simultaneously recorded in one command packet.

The instruction packet (INSTRUCTION PACKET) used in the present invention is a packet in which the master device instructs the slave device to operate, and its structure is as follows.

The meaning of each byte of the command packet is as follows.

0XFF 0XFF: The two leading 0XFFs are signals to signal the beginning of the packet.

ID: ID of the slave device to be controlled by the command packet. The ID of the slave device can be 254 from 0X00 to 0XFD.

Broadcasting ID: It is an ID that designates all connected slave devices. A broadcasting ID packet with the ID set to 0XFE is valid for all connected slave devices. Therefore, in the case of a packet transmitted with a broadcasting ID, a status packet is not returned.

LENGTH (length): Length of the command packet. Its value is "number of parameters [N] + 2".

INSTRUCTION (command): This command instructs the slave device to execute.

PARAMETER 0 ... N: Used when additional information is needed in addition to INSTRUCTION.

CHECK SUM (Checksum): The calculation method of the checksum is as follows.

Check SUM = ~ {ID + LENGTH + INSTRUCTION + PRAMETER 1 + ... + PRAMETER N}, if the value computed by the checksum is greater than 255, the lower byte of the result is CHECK SUM. "~" Is the Not Bit operator.

The status packet (STATUS PACKET) used in the present invention is a packet that the slave device returns to the main controller in response to receiving the command packet, and the structure thereof is as follows.

The meaning of each byte in the status packet is as follows.

0XFF 0XFF: The two leading 0XFFs are signals to signal the beginning of the packet.

ID: ID of the slave device that returns the status packet. The ID of the slave device can be 254 from 0X00 to 0XFD.

LENGTH (length): length of the status packet whose value is "number of parameters [N] +2".

ERROR (Error): Indicates error status occurred during operation of slave device.

Bit designation Contents Bit 7 0 - Bit 6 Instruction
Error If an undefined instruction is sent, it is set to 1 if an ACTION command is passed without a REG_WRITE command. Bit 5 Overload Error Set to 1 when the current load can not be controlled with the specified maximum torque. Bit 4 Checksum Error Set to 1 when check sum of transmitted instruction packet is not correct Bit 3 Range Error Set to q for commands out of range Bit 2 Overheating Error Dynamixel is set to 1 when the internal temperature is outside the operating temperature range set in the control table. Bit 1 Angle Limit Error Goal Position is set to 1 when Written as CW Angle Limit ~ CCW Angle Limit value Bit 0 Input Voltage Error Set to 1 if the applied voltage is outside the operating voltage range set in the control table.

PARAMETER 0 ... N: Used when more information is needed in addition to ERROR.

CHECK SUM (Checksum): The calculation method of the checksum is as follows.

Check SUM = ~ {ID + LENGTH + ERROR + PRAMETER 1 + ... + PRAMETER N}, if the value computed by the checksum is greater than 255, the lower byte of the result is CHECK SUM. "~" Is the Not Bit operator.

The instruction set used in the slave device of the present invention has the kind shown in Table 6. In addition, the extension of these commands is merely illustrative of BULK_READ and BULK_WRITE, and it is necessary to define new parameters as well as add new commands.

Instruction Fuction Value Number of Parameter PING No action. Use when Dynamixel wants to return Status Packet 0X01 0 READ_DATA Command to read the value of the Control Table 0X02 2 WRITE_DATA Commands to write values to the Control Table 0X03 2 ~ REG_WRITE WRITE DATA is similar to the contents, but it is in WAIT state and WRITE when ACTION command arrives 0X04 2 ~ ACTION REG WRITE command to start the registered operation 0X05 0 RESET Change Control Table value in Dynamixel to Factory Default Value 0X06 0 SYNC_WRITE Commands used to control several modules at once 0X83 4 ~ BULK_READ Commands that read data of different addresses and lengths to multiple modules at once 0X92 BULK_WRITE Command to WRITE data of different address and length to several modules at once 0X93

1. WRITE_DATA

Function: This command is used to write data to the control table in the slave unit.

Length: When the number of data to be recorded is N, the length is N + 3.

Command: 0X03

Parameter 1: Start address of data recording area

Parameter 2: The first data to be recorded

Parameter 3: The second data to be recorded

Parameter N + 1: Nth data to be recorded

For example, when setting the ID of the connected slave device to 1, an instruction to write 1 to address 3 of the control table may be transmitted.

The command packet when transmitting with the broadcasting ID (0XFE) is as follows.

In this case, the status packet is not returned because it was sent with the broadcasting ID.

2. READ_DATA

Function: Command to read the data of the control table in the slave unit

Length: 0X04

Command: 0X02

Parameter 1: Starting address of data to be read

Parameter 2: Length of data to be read

for example. To read the current internal temperature of a slave device with ID 1, read 1 byte from the address 0X2B in the control table. The command packet in this case is as follows.

The status packet returned for this is as follows.

The read data value is 0X20 and it can be seen that the internal temperature of the slave device is about 32 ° C [0X20].

3. REG_WRITE

Function: The REG_WRITE command is similar to the WRITE_DATA command, but the time at which the command is executed is different. When a REG_WRITE command packet arrives, its value is stored in the buffer and the WRITE operation remains in the WAIT state. At this time, Registered Instruction [0X2C] is set to 1. When the ACTION command packet arrives later, the registered REG_WRITE command is executed.

Length: N + 3

Command: 0X04

Parameter 1: Start address of the place where data is to be recorded

Parameter 2: The first data to be recorded

Parameter 3: The second data to be recorded

Parameter N + 1: Nth data to be recorded

4. ACTION

Function: Command to perform WRITE operation registered by REG_WRITE command

Length: 0X02

Command: 0X05

Parameters: none

Here, the ACTION command is useful when it is necessary to correctly operate a plurality of slave devices simultaneously. When controlling a plurality of slave devices with command packets, a slave device that receives the first command and a slave device that receives the last command cause a slight time difference at the time of operation. However, using the REG_WRITE and ACTION commands solves this problem. On the other hand, when sending an ACTION command to two or more slave devices, the broadcast ID (0XFE) must be used, and the status packet is not returned.

5. PING

Function: The PING command does not indicate anything. It is used only to receive a status packet or to confirm the existence of a slave device having a specific ID.

Length: 0X02

Command: 0X01

Parameters: none

For example, when it is desired to obtain a status packet of a slave device having ID 1, the PING command can be used as follows.

The corresponding status packet returned is as follows.

If the broadcast ID is specified or the status return level [0X10] is 0, a status packet is returned for the PING command.

6. RESET

Function: Returns the control table of the slave unit to the factory default state.

Length: 0X02

Command: 0X06

Parameters: none

For example, a command packet for resetting a slave device whose ID is 0 is as follows.

The status packet returned for the RESET command is as follows.

Here, after the execution of the RESET command, the ID is changed to 1.

7. SYNC_WRITE

Function: This command is used to control multiple slave devices at the same time by transmitting a single command packet. Sync Write command allows multiple commands to be sent at once, reducing communication time when controlling multiple slave devices. However, the address and length of the control table to be written in each slave device must be the same, and the ID must be transmitted in the broadcasting ID.

ID: 0XFE

Length: [L + 1] * N + 4, where L is the data length of the slave device and N is the number of slave devices.

Command: 0X83

Parameter 1: Start address where data is recorded

Parameter 2: Length of data to be recorded [L]

Parameter 3: ID of the first slave device

Parameter 4: First data of the first slave device

Parameter 5: Second data of the first slave device

.....

Parameter L + 3: Lth data of the first slave device

Parameter L + 4: ID of the second slave device

Parameter L + 5: First data of the second slave device

Parameter L + 6: Second data of the second slave device

......

Parameter 2L + 4: Lth data of the second slave device

......

For example, let's define the position and speed for each of the four slave devices as shown below.

Slave device with ID 0: Move to speed 0X150 to position 0X010

Slave device with ID 1: Move to 0X220 position to speed 0X360

Slave device with ID 2: Move to 0X030 position to speed 0X170

Slave device with ID 3: Move to 0X220 position to speed 0X380

An instruction packet for instructing this operation is as follows.

0XFF 0XFF 0XFE 0X18 0X83 0X1E 0X04 0X00 0X10 0X00 0X20 0X0 0XX 0X20 0X0 0XX 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

At this time, the status packet is not returned because it is transmitted with the broadcasting ID.

8. BULK_READ

Function: This command is used to read data from multiple slave devices at the same time by sending a single command packet.

Compared to issuing multiple READ commands, the length of the packet is reduced, and idle time is reduced between returned status packets, saving communication time.

ID: 0XFE

Length: 3N + 3

Command: 0X92

Parameter 1: 0X00

Parameter 2: Length of the data to be read from the first module [L]

Parameter 3: ID of the first module

Parameter 4: Start address of the data to be read from the first module

....

Parameter 3N + 2: Length of the data to be read from the Nth module [L]

Parameter 3N + 3: ID of the Nth module

Parameter 3N + 4: Starting address of the data to be read from the Nth module

....

For example, assume that the following values are read for the two slave devices, respectively.

Slave device with ID 1: Get the target position value (2 bytes from 0X1E).

Slave device with ID 2: Get the current position value (2 bytes from 0X24).

An instruction packet for instructing this operation is as follows.

0XFF 0XFF 0XFE 0X09 0X92 0X00 0X02 0X01 0X1E 0X02 0X02 0X24 0X1D

At this time, the module with ID 2 monitors the status packet of the module which is ID 1 (ID of the immediately preceding parameter) on the data bus, and transmits the status packet of the module with ID 1 do.

The returned status packet looks like this:

0XFF 0XFF 0X 00 0X 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

The status packets sent from module ID 1 and ID 2, respectively, come in a succession of incoming packets.

9. BULK_WRITE

Function: It is a command used to simultaneously write a value in a plurality of slave devices by sending a single command packet.

Compared to multiple WRITE commands, the length of the packet is reduced and the idle time between each packet is reduced, saving communication time.

You can also specify the same ID multiple times to write a value to a contiguous control table in one module.

ID: 0XFE

Length: Variable

Command: 0X93

Parameter 1: 0X00

Parameter 2: Length of the data to write to the first module [L1]

Parameter 3: ID of the first module

Parameter 4: First data of the first module

Parameter 5: Second data of the first module

...

Parameter L1 + 2 * 1 + 1: Lth data of the first slave device

Parameter L1 + 2 * 2 + 0: Length of data to write to the second module [L2]

Parameter L1 + 2 * 2 + 1: ID of the second module

Parameter L1 + 2 * 2 + 2: First data of the second module

...

Parameters L1 + L2 + ... + LN + 2 * N + 1: Lth data of the Nth slave device

...

For example, suppose that the values for the two slave devices are set as follows.

Slave device with ID 1: Move to 0X220 position to speed 0X360

Slave device with ID 2: Change CW / CCW Compliance Slope to 0X16

An instruction packet for instructing this operation is as follows.

0XFF 0XFF 0XFE 0X0D 0X93 0X00 0X04 0X0 0X20 0X02 0X60 0X03 0X02 0X02 0X10 0X10 0XB0

At this time, the status packet is not returned because it is transmitted with the broadcasting ID.

As such, the instruction set can be added continuously, and the parameter contents are classified according to each instruction set.

Therefore, it is possible to flexibly extend the constraints according to the length limitation of each field according to the instruction set and the parameter definition.

For example, suppose you set the instruction set BULK_READ_2 to 0XA0 and specify the parameters as shown below.

ID: 0XFE

Command: 0XA0

Parameter 1: ID of the first module Lower byte

Parameter 2: ID of the first module High byte

Parameter 3: Start address of data to be read from the first module Lower byte

Parameter 4: Start address upper byte of data to be read from the first module

Parameter 5: Length of data to be read from the first module Low byte

Parameter 6: Length of the data to be read from the first module High byte

 If it is specified in this form, the ID of the slave device, the address of the control table, and the length of the data are set to 1 byte, so that constraints that can be assigned only from 0 to 255, which is a naturally occurring restriction, can be extended. It will be understood by those skilled in the art that the foregoing description of the present invention is for illustrative purposes only and that those of ordinary skill in the art can readily understand that various changes and modifications may be made without departing from the spirit or essential characteristics of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is defined by the appended claims, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

1: communication system
10: Master device
20: Slave device
30: Communication bus

Claims (8)

A packet collision avoiding method in a communication system having a master device and a plurality of slave devices connected in a multi-drop manner and using different protocols,
Wherein the master device transmits a quarantine packet to a specific slave device,
Wherein the specific slave device does not receive the command packet when the command packet is transmitted from the master device after receiving the quarantine packet from the master device, A method for preventing packet collisions in a communication system supporting a packet collision. The method according to claim 1,
Wherein the step of transmitting the isolation packet comprises:
Wherein the master device transmits a quarantine packet to a slave device using a specific protocol. The method according to claim 1,
Wherein the step of not receiving or discarding the command packet comprises:
Wherein the step of not receiving or discarding the command packet transmitted from the master device for a predetermined period of time is to discard the command packet. The method according to claim 1,
Wherein the step of not receiving or discarding the command packet comprises:
Wherein the step of not receiving or discarding a command packet of a number of bytes or less that is transmitted from the master device is less than a predetermined number of bytes. The method according to claim 1,
Wherein the master device transmits an isolation release packet to the specific slave device,
Further comprising the step of executing the command packet when receiving the command packet from the master device after receiving the isolation cancellation packet from the master device Method for preventing packet collision in communication system. The method according to claim 1,
Wherein the isolation packet is designed to be different for each protocol. The method according to claim 1,
Wherein the command packet is generated by checking an address of a value to be controlled through a control table of each of the slave devices and then referring to an ID and an address. The method according to claim 1,
Wherein each of the slave devices is an actuator driven by the master device.

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