JP2008048395A - Master / slave synchronous communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a communication delay constant regardless of a control cycle in a synchronous communication system in which a master and all slaves connected on an IEEE 1394 network exchange control data within a control cycle.
A master creates a synchronous communication management table in which master control data transmission / reception timing and control processing timing are set based on a synchronization unit, a control cycle, and the number of slaves. Also, based on the synchronous communication management table, a synchronous communication information data table in which slave control data transmission / reception timing, command execution and response generation timing are set is created and notified to the slave. The master and the slave communicate according to their synchronous communication management table and synchronous communication information data table.
When there are a plurality of control cycles, a synchronous communication management table and a synchronous communication information data table in which the timing is shifted by the synchronization unit are created.
[Selection] Figure 1

Description

  The present invention relates to a master-slave synchronous communication system and synchronous communication system using an IEEE 1394 network.

  In the isochronous transfer of the conventional IEEE 1394 communication system, the device that performs the isochronous transfer acquires the bandwidth and channel from the isochronous resource manager (hereinafter referred to as IRM) in advance, and when the cycle start packet is received, the right to use the bus is obtained. The acquired device sends data. Each communication device acquires the right to use the bus in order during the isochronous transfer period and transmits data (for example, see Non-Patent Document 1).

  Normally, all communication devices are configured to transfer data during the isochronous transfer period, so if you want to add a new device but the remaining bandwidth is less than the bandwidth you want to acquire, the data for one device will be It will decrease, or you will not be able to add new equipment.

To solve such a problem, the control cycle is an integer multiple of the isochronous cycle, the master assigns the number of slaves to be controlled to the isochronous cycle for the control cycle, and the control data is transferred to and from the slaves in order according to the assignment. By performing the above, there is disclosed a technique that enables construction of a master-slave synchronous communication system using IEEE 1394, which is a general-purpose high-speed communication network. This will be described with reference to FIGS.

FIG. 18 is a communication timing management table for synchronously communicating one master station and eight slave stations with a control period of 500 μs, and is divided into four isochronous cycles, with four isochronous cycles corresponding to 500 μs. Of these, communication is set to be performed using the first two isochronous cycles. FIG. 19 is a timing chart in which communication is performed in accordance with the communication timing management table of FIG. 18. In the first 125 μs of 500 μs, the master transmits command data C1 to C4 to the slaves 1 to 4, and the slaves 1 to 4 transmit to the master. Response data R1 to R4 are transmitted. Further, during the second isochronous cycle of 125 μs to 250 μs, the master transmits command data C5 to C8 to the slaves 5 to 8, and the slaves 5 to 8 transmit response data R5 to R8 to the master. . (See Patent Document 1)
Japanese Patent Laying-Open No. 2005-229142 (FIGS. 2 and 3) IEEE Std 1394-1995, IEEE Standard for a High Performance Serial Bus

However, in the synchronous communication system described in Patent Document 1, as shown in FIG. 20, the master control unit and the communication unit, and the slave control unit and the communication unit are synchronized in the control cycle (an integral multiple of the isochronous cycle). Data transmission / reception.
That is, when paying attention to a certain control cycle N, the control units of all slaves simultaneously generate response data in the isochronous cycle of # 3 in the cycle counter of the control cycle N-2 two cycles before and pass it to the slave communication unit. The slave communication unit transmits response data in the determined isochronous cycle of the control cycle N-1.
The master communication unit receives the response data for each cycle of the control cycle N−1, passes the response data of all slaves to the master control unit in the cycle in which the cycle counter of the next control cycle N is # 0, and the master control unit Command data is created based on the response data within the control cycle, and the command data is passed to the master communication unit.
The master communication unit transmits command data to each slave in order at a control cycle N + 1.
And the slave communication part delivers command data to the slave control part all at once by the cycle counter # 0 of the control period N + 2 after the lapse of the control period.

That is, transmission of response data from the slave to the master, creation of the next command data based on the response data, transmission of the command data to the slave, execution of processing of the command data in the slave are synchronized with the control cycle. Was running.
Therefore, the control period is included in the delay (hereinafter referred to as “communication delay”) of communication in response data reception and command data transmission, and communication is performed as shown in cycles # 2 and # 3 in FIG. Even if there is no isochronous cycle, the communication delay is not shorter than the control cycle, which hinders improvement in control performance.
Further, in a system in which the control cycle is long because control processing takes time, there is a problem that communication delay becomes long and hinders improvement in control performance.
The present invention has been made in view of such problems. The master receives response data from the slave, creates command data for the slave, and transmits the command data to the slave. Receives command data from the master, executes the command data, creates response data to the master, automatically generates a table that defines the timing for transmission to the master, prepares the table in the master and slave, and communicates The present invention provides a master / slave synchronous communication system in which the delay is reliably suppressed to a constant value equal to or less than the control period.

In order to solve the above problems, the present invention is as follows.
According to the first aspect of the present invention, a master station in which one master and one or more slaves are connected to an IEEE 1394 network, and the master and the slave communicate with each other in synchronization with a control cycle that is an integral multiple of an isochronous cycle. In a slave synchronous communication system,
In the case of reception from the slave, a synchronization unit that means a time in an isochronous cycle unit necessary for communication with all the slaves is set from the end of the control cycle, and transmission to the slave is performed by the master. In the case of, comprising a synchronous communication management table in which the synchronization unit is set from the beginning of the control cycle,
Synchronous communication information in which the slave sets the synchronization unit from the end of the control cycle when transmitting to the master, and sets the synchronization unit from the beginning of the control cycle when receiving from the previous period master. A data table is provided.

The invention according to claim 2 is the timing according to the invention according to claim 1, wherein the synchronous communication management table provided in the master starts a control process in which the master creates command data for the slave. The number of slaves and the slave number transmitted by the master and the number of slaves and the slave number received by the master are held for each timing,
The synchronous communication information data table included in the slave includes the timing at which the slave receives command data from the master, the timing at which the command data is executed, and the timing at which response data to the master is created. And the timing for transmitting response data to the master.

  According to a third aspect of the present invention, in the first aspect of the present invention, the slave allocating unit provided in the master communicates within the preset synchronization unit, the control period, and the synchronization unit. The synchronous communication management table is created based on control period data composed of the number of slaves to be performed and an array of slave numbers that uniquely specify the slaves, and the synchronous communication information is based on the synchronous communication management table It is characterized by creating a data table.

According to a fourth aspect of the present invention, in the first aspect of the present invention, when the master detects a timing for starting the control process according to the synchronous communication management table, the control process is executed, and the slave When the reception timing from is detected, reception is performed, and when the transmission timing to the slave is detected, transmission is performed,
According to the synchronous communication information data table, the slave receives command data from the master when detecting the timing to receive the command data, and executes processing of the command data when detecting the timing to execute the command data. The response data is generated when the response data generation timing is detected, and the response data is transmitted to the master when the response data transmission timing is detected.

  The invention according to claim 5 is the invention according to any one of claims 1 to 4, wherein there are a plurality of the control cycles in which the master and the slave communicate, and the slave is in each control cycle. The synchronous communication management table and the synchronous communication information data table are created by shifting the control cycle by the synchronization unit for each group.

  According to a sixth aspect of the present invention, in the invention according to any of the first to fifth aspects, when the slave allocation unit creates a synchronous communication management table based on the previous period control period data, When an isochronous cycle that does not perform communication within a unit is detected, the synchronization unit is shortened to an optimum value.

  Further, in the invention according to claim 7, in the invention according to any one of claims 1 to 5, communication is performed when the slave allocation unit prepares the synchronous communication management table based on the control period data of the previous period. When it is detected that the time exceeds the previous synchronization unit, the synchronization unit is extended to an optimum value.

  The invention according to claim 8 is the invention according to any one of claims 1 to 7, wherein the first-term master or first-term slave or first-term master and first-term slave notifies the user of the optimized synchronization unit. It is characterized by.

According to the invention described in claims 1 to 4, the master and the slave are based on the synchronous communication management table provided in the master and the synchronous communication information data table provided in the slave.
Since communication is performed in synchronization units equal to or less than the control period, the communication delay remains constant in the synchronization units, and control performance can be improved.
Further, even if the control process in the master takes time and the control cycle becomes long, the communication delay remains constant in the synchronization unit, and the control performance can be improved.

According to the fifth aspect of the present invention, since communication data is exchanged in synchronization units equal to or less than the control period while shifting the communication timing by the synchronization unit for each group having a different control period, the communication delay of each group is the synchronization unit. As a result, the control performance can be improved.
Moreover, even if the control processing at the master takes time and the control cycle becomes long, the communication delay remains constant in the synchronization unit, and the control performance can be improved.

Further, by controlling slaves in groups, it is not necessary to create command data for a plurality of functions in one control cycle.
For example, the lower body and upper body of a biped robot are divided into groups, and the lower body that requires more response performance is set to have a shorter control cycle so that the robot does not fall down. Even if the control cycle is set to be long, the communication delay is constant and the control performance can be ensured.
For example, by making the right arm and left arm of a double-arm robot in separate groups even in the same control cycle, the number of slaves in one group is reduced, and the isochronous cycle for transferring control data to and from each group is shortened. The operation between the right arm and the left arm ensures synchronization without affecting control, and each communication delay is shortened, so that the performance as one arm can be improved.

  According to the inventions described in claims 6 to 7, it is possible to automatically operate in an optimum synchronization unit, and the number of slaves that can communicate within one isochronous cycle depends on the communication speed, hardware restrictions, and the like. There is no need to change the settings each time it changes.

  According to the eighth aspect of the present invention, the synchronization unit optimized in the sixth to seventh aspects can be recognized, and an application program can be created in consideration of communication delay.

  Hereinafter, specific examples of the method of the present invention will be described with reference to the drawings.

  First, function names and signal names defined in the IEEE 1394 standard, which appear in the following description, will be described.

  FIG. 14 is a diagram showing the format of the minimum format of the configuration ROM possessed by the IEEE 1394 equipment, and includes a vendor ID called 24-bit vendor_id representing vendor-specific information.

  FIG. 15 is a diagram illustrating a general format format of a configuration ROM included in the IEEE 1394 device, and FIG. 16 is a diagram illustrating a format of a bus_info_block included in FIG. 14 includes a vendor ID (node_vendor_id) similar to that in FIG. 14 and a 40-bit chip ID in which an 8-bit chip_id_hi and a 32-bit chip_id_lo are concatenated to make a device unique within the vendor. The 64-bit information combining the vendor ID and the chip ID is called EUI-64 (Extended Unique Identifier, extended unique identifier, 64 bits), and is information that can be uniquely identified in all IEEE 1394 devices.

  FIG. 17 is a diagram showing the format of the CYCLE_TIME register of the IEEE 1394 device, and includes second_count, cycle_count, and cycle_offset. Second_count increases each time a carry from cycle_count occurs, and when it increases when the value is 127, it circulates and returns to zero. The cycle_count increases each time a carry from the cycle_offset occurs. When the value increases when the value is 7999, the cycle_count circulates back to 0, and rises to the second_count. The unit of cycle_count is 125 μs. The cycle_offset increases every tick of the 24.576 MHz local clock. When the value increases when the value is 3071, it cyclically returns to 0 and is carried to the cycle_count.

  The cycle start packet is a packet indicating the start of an isochronous cycle defined in the IEEE 1394 standard, and is transmitted by the device that becomes the cycle master every 125 μs of the natural period.

FIG. 1 is a configuration diagram of a master-slave synchronous communication system showing an embodiment of the present invention. In the figure, 1 is a master, 2i (i = 1, 2,... N) is a slave, and 3 is an IEEE 1394 network.

  The master 1 includes a control cycle data 11, a slave detection unit 12, a connection slave information 121 detected by the slave detection unit 12, a slave allocation unit 13 that allocates communication timings, etc., and an allocated synchronous communication A synchronous communication management table 14 for storing information, a cycle start packet reception processing unit 15 for calculating processing timing, a command data transmitting unit 16 and command data 161 to be transmitted, a response data receiving unit 17 and received response data 171 The control processing unit 18 reads the response data 171 and creates the command data 161.

However, in the systems according to claims 1 to 2 and 4, the synchronous communication management table 14 may be created as a program in advance, or may be set by other devices to notify the master 1 by other means. Alternatively, the control cycle data 11, the slave detection unit 12, the connection slave information 121, and the slave allocation unit 13 can be omitted.

On the other hand, the slave 2i includes a command data receiving unit 2i1, received command data 2i11, response data 2i2, response data 2i21 to be transmitted, a synchronous communication processing unit 2i3 for performing transmission / reception processing, and synchronous communication in which each processing timing is stored. An information data table 2i31, a cycle start packet reception process 2i4 for calculating each processing timing, a response creation unit 2i5 for creating response data, and a command processing unit 2i6 for executing command data.

FIG. 2 is a detailed diagram of the control cycle data according to the first embodiment of the present invention, and is a detailed diagram of the control cycle data 11 of FIG. 1, in which the synchronization unit, the number of groups into which the slave is divided, the control cycle, and the control slave It consists of a number and a control slave number. In the present embodiment, an example of one group in which the synchronization unit is 250 μs, the control cycle is 500 μs, the number of control slaves is 4, and the control slave numbers are S1, S2, S3, and S4 is shown.
The synchronization unit is a time corresponding to the number of consecutive isochronous cycles required for the master to communicate (receive or transmit) with all the slaves, and is a time in units of 125 μs, which is an isochronous cycle time.

FIG. 3 is a detailed view of the synchronous communication management table 14 of FIG. 1 according to the first embodiment of this invention. The synchronous communication management table 14 includes the total number of cycles in which the number of isochronous cycles corresponding to the control cycle is stored, the control processing start timing of the master, the number of transmission slaves indicating the number of slaves that transmit command data in each cycle, and the transmission It consists of a transmission slave number that represents the previous slave, a response slave number that represents the number of slaves that receive response data, and a reception slave number that represents the source slave. As an embodiment of the present invention, data is shown in the case where the number of slaves that can communicate in one cycle is set in four slave stations with the same control cycle 500 μs as the control cycle data in FIG.

  Here, cycle # is the value of the remainder (remainder) when the cycle_count value of CYCLE_TIME at the time of receiving the cycle start packet is divided by the number of isochronous cycles corresponding to the control period. That is, the value increases by circulating 0 to the number of isochronous cycles minus 1, and the value of each timing means the timing when the cycle # becomes the set value.

  FIG. 4 is a detailed view of the synchronous communication information data table 2i31 (i = 1 to 4) of FIG. 1 according to the first embodiment of the present invention. The synchronous communication information data table 2i31 is composed of the number of isochronous cycles corresponding to the control period, the timing for receiving command data, the timing for executing command data, the timing for creating response data, and the timing for transmitting response data. The As the first and second embodiments of the present invention, data of the slave 2i (i = 1 to 4) corresponding to the synchronous communication management table of FIG. 3 is shown.

  FIG. 5 is a communication timing chart according to the first embodiment of the present invention. The master is the synchronous communication management table of FIG. 3, and each slave is operated according to the synchronous communication information data table of FIG. 4. Paying attention to the master control processing of a certain control cycle N, each slave of the control cycle N−1 FIG. 9 is a diagram showing a state in which command data is created based on the response data of the above, command data is transmitted to each slave in the control cycle N + 1, and each slave takes in and executes the command data. Actually, the same processing is executed for each control cycle, but here, the processing appearing in the figure will be described in the order of the slave response in the control cycle N-1 to the master command in the control cycle N + 1.

  First, at the timing of the control cycle N-1 and cycle # 1, the slave 2i (i = 1 to 4) creates response data at the same timing.

  Further, at the timing of the control cycle N-1 and cycle # 2, the slave 2i (i = 1, 2) transmits the response data Ri (i = 1, 2), and the control cycle N-1 and cycle # 3. At the timing, the slave 2i (i = 3, 4) transmits response data Ri (i = 3, 4).

  Next, at the timing of the control cycle N and cycle # 0, the master 1 activates the control process, and receives the command data Ci (i = 1 to 4) based on the received response data Ri (i = 1 to 4). create. This control process is executed as a high-speed process that does not interfere with the communication process or a low-priority process.

  The master 1 transmits the command data Ci (i = 1, 2) at the timing of the control cycle N + 1 and cycle # 0, and the slave 2i (i = 1, 2) receives it, and the timing of the control cycle N + 1, cycle # 1. Then, the master 1 transmits the command data Ci (i = 3, 4), and the slave 2i (i = 3, 4) receives it.

Finally, the slaves 2i (i = 1 to 4) execute commands simultaneously at the timing of the control cycle N + 1 and cycle # 2. Slave command execution processing is also executed as high-speed processing that does not interfere with slave communication processing or low-priority processing.

  Therefore, with respect to the response data, all slaves simultaneously generate response data before the synchronization unit, that is, 250 μs before (125 to 250 μs timing), and the master 1 and slave 2 i (i = 1, 2) between 250 and 375 μs. ), The master 1 and the slave 2i (i = 3, 4) can send and receive response data during 375 to 500 μs, not the data before the control period, but before a certain communication delay, that is, the set synchronization The master can acquire the slave information at the same timing before the unit as response data.

  As for command data, master 1 and slave 2i (i = 1, 2) in the first 125 μs, and master 1 and slave 2 i (i = 3, 4) send and receive command data between 125 and 250 μs. All slaves can start command execution at the same time 250 μs after the synchronization unit (command timing is 250 to 375 μs) after the command data has been transferred to all slaves. Later, the slave can execute the command data synchronously.

  Actually, the process is defined in cycle #, the same process is executed for each control period, and the control period is 500 μs. Therefore, cycle # is repeated from 0 to 3.

  As described above, the master 1 can exchange communication data with all the slaves 2i (i = 1 to 4) within the control period of 500 μs, and is set after a certain communication delay, that is, without waiting until after the control period. The slave synchronizes to execute the command data after the synchronization unit, and the master data is not the data before the control cycle, but the slave data at the same timing before the set communication unit as a response data before a certain communication delay. Can get.

  FIG. 6 is a flowchart showing the communication initialization processing procedure of the synchronous communication method in the first master-slave synchronous communication system of the present invention. The procedure for creating a synchronous communication management table used by the slave assignment unit 13 of the master for synchronous communication and a synchronous communication information data table used by the slave for synchronous communication from the control cycle data will be described in order. .

First, in step S010, control cycle data 11 in which a control cycle, the number of slaves, a slave number, and the like are set in advance is extracted.

Next, in S020, the slave set in the control cycle data 11 is associated with the device connected on the network. This detects all slave information 121 connected on the network using the function of the IEEE 1394 standard described in Non-Patent Document 1, and a communication slave number for communication between the slave and the master. Here, the slave information 121 indicates the vendor ID shown in FIG. 14 or the information on the EUI-64 shown in FIG. 16, and the slave information 121 is used to determine a device that is a slave. The slave number may be information registered in the slave station, or may be a node ID assigned to an IEEE 1394 device connected on the network as a function of the IEEE 1394 standard.

In S030, the number of slaves capable of synchronous communication in one isochronous cycle is calculated as the number of slaves capable of communication in the cycle. Here, the number of slaves that can be communicated in the cycle is a hardware restriction of the number of DMA contexts when using an OHCI-compliant IEEE 1394 interface. If there is no hardware restriction, the bandwidth of the command data, the bandwidth of the response data, According to the communication speed of the device, it can be obtained by equation (1). (In this embodiment, the number of slaves that can communicate in a cycle is 2)

Number of slaves that can communicate within a cycle = Isochronous transfer bandwidth ÷ Send / receive bandwidth for one slave (1)
Transmission / reception bandwidth for one slave = {(header + command data bandwidth) + command data transmission gap
+ (Header + response data bandwidth) + response data transmission gap}

The header, the gap at the time of command data transmission, and the gap at the time of response data transmission are bands specified in the IEEE 1394 standard.

Next, whether or not communication timing allocation is possible is determined in S040 using equation (2). If equation (2) is established, the process proceeds to 050. If not established, error processing is performed in S041 and the process is terminated.

Total number of slaves ÷ Number of slaves that can communicate within a cycle ≦ Total number of cycles (2)
Total number of cycles = Control period [μs] ÷ 125 [μs] (3)
125 μs: Isochronous cycle time defined by the IEEE 1394 standard

Next, in S050, it is composed of the number of transmission slaves and the number of transmission slaves, which are the transmission data part of the synchronous communication management table 14 for the number of isochronous cycles constituting the control cycle, from the control cycle data 11 and the number of slaves capable of communication within the cycle. Create a transmission timing table, and assign the set slaves in order.

Next, in S060, the area of the synchronous communication management table 14 for the total number of cycles calculated by the expression (3) is secured, cleared to 0, the total number of cycles is set, and the transmission data part stores data according to the transmission timing table.

  In S120, the cycle in which the slave to be transmitted first is assigned is set as the master control processing start timing.

As a cycle # for starting the allocation of the reception slave number in S130, the reception allocation start cycle # is calculated by the equation (4).

Receive allocation start cycle # = total number of cycles-number of synchronization unit cycles (4)
Synchronization unit cycle count = Synchronization unit [μs] ÷ 125 [μs]

In S140, the number of transmission slaves and transmission slave number in cycle # 0 are copied to the number of response slaves and reception slave number in reception allocation start cycle #. This process is repeated for the total number of cycles while shifting the transmission cycle # and the reception cycle # one cycle at a time to create a reception data portion of the synchronous communication management table.

In S150, the slave command execution timing and response creation timing are calculated by equations (5) and (6), respectively.

Command execution timing = MOD ((Control processing start timing + number of synchronization unit cycles),
Number of control cycle cycles) (5)
Response creation timing = MOD ((reception allocation start cycle # + number of control cycle cycles-1),
Number of control cycle cycles) (6)
MOD (A, B): remainder of A by B

In S160, the command reception timing and response transmission timing for each slave are extracted from the synchronous communication management table 14 created in the above steps, and the number of cycles corresponding to the control cycle, command execution timing, and response creation timing data, In addition, it notifies all slaves as a synchronous communication information data table.

Thus, the synchronous communication management table 14 in FIG. 3 is created in the master 1 and the synchronous communication information data table 2 i 31 in FIG. 4 is created in each slave 2 i.
The synchronous communication management table 14 and the synchronous communication information data table 2i31 are created by an engineering tool mounted on a personal computer or the like that exists outside the master / slave synchronous communication system, and the master of the system via a network or the like. Or download it to the slave.

FIG. 7 is a flowchart showing a processing procedure when a cycle start packet is received after the master synchronous communication is started in the master-slave synchronous communication system of the present invention. In this figure, event processing when the master receives a cycle start packet will be described step by step.

  First, in S1000, cycle # is calculated.

  Next, in step S1010, cycle # timing data is extracted from the synchronous communication management table for the number of transmission slaves, the transmission slave number, the number of response slaves, and the reception slave number.

  If the response slave number extracted in S1020 is not 0, the response data of the reception slave number is received.

If the number of transmission slaves extracted in S1030 is not 0, the transmission slave number command data is transmitted.

If the control process start timing coincides with cycle # in S1040, the corresponding control process is started.

  From S1000 to S1040, a synchronous communication process is executed as an event process when a master cycle start packet is received.

FIG. 8 is a flowchart showing a processing procedure when a cycle start packet is received after the slave synchronous communication is started in the master-slave synchronous communication system of the present invention. In this figure, event processing when the slave receives a cycle start packet will be described step by step.

  First, in step S2000, cycle # is calculated.

  Next, the synchronous communication information data table is read in S2010, and when the command reception timing is equal to cycle # in S2020, the command data is received in S2030.

  When the command execution timing is equal to cycle # in S2040, the command is executed in S2050. Or start command processing.

  When the response creation timing is equal to cycle # in S2060, response data is created in S2070.

  When the response transmission timing is equal to cycle # in S2080, response data is transmitted in S2090.

  From S2000 to S2080, a synchronous communication process is executed as an event process when a slave cycle start packet is received.

  6 to 8, the synchronous communication management table of FIG. 3 and the synchronous communication information data table of FIG. 4 are created from the control cycle data of FIG. 2, and the master and slave are as shown in the communication timing chart of FIG. Therefore, the master and all slaves can exchange control data within the control cycle, and synchronous communication can be performed with a constant communication delay that is less than the control cycle and does not depend on the control cycle. .

FIG. 9 is a detailed view of the control cycle data 11 of FIG. 1 according to the second embodiment of the present invention. In the example in which the control cycle data of FIG. 2 is provided for a plurality of groups, in this embodiment, the synchronization unit is 250 μs, the control cycle is 500 μs, the number of control slaves is 4, and the control slave numbers are S1, S2, S3. An example of two groups, group 1 with S4 and control period 1 ms = 1000 μs, number of control slaves 4 stations, and group 2 with control slave numbers S5, S6, S7, and S8 is shown.

  FIG. 10 is a detailed view of the synchronous communication management table 14 of FIG. 1 according to the second embodiment of the present invention. The configuration is the same as in FIG. 3, and since there is a group 2 with a control period of 1 ms, the total number of cycles is 8. As an embodiment of the present invention, in the setting of the control cycle data in FIG. 9, data is shown when the number of slaves that can communicate in one isochronous cycle is two stations.

  FIG. 11 is a detailed view of the synchronous communication information data table 2i31 (i = 1 to 8) of FIG. 1 according to the second embodiment of the present invention. The synchronous communication information data table 2i31 (i = 1 to 8) includes the number of isochronous cycles corresponding to the control cycle, the timing of receiving command data, the timing of executing command data, the timing of creating response data, and the response data It is comprised from the timing which transmits. As the third and fourth embodiments of the present invention, data of the slave 2i (i = 1 to 8) corresponding to the synchronous communication management table of FIG. 9 is shown. Here, the synchronous communication information data table 2i31 (i = 1 to 4) regarding 2i (i = 1 to 4) is the same as FIG.

  FIG. 12 is a communication timing chart according to the second embodiment of the present invention. The master operates in accordance with the synchronous communication management table in FIG. 10, and each slave operates in accordance with the synchronous communication information data table in FIG. The timing chart regarding 2i (i = 1 to 4) is the same as FIG. 5, and the basic operation of the slave 2i (i = 5 to 8) is the same as FIG.

  From FIG. 12, as in FIG. 5, the group 1 can exchange communication data with all the slaves 2i (i = 1 to 4) in which the master 1 is set in the group within the control period of 500 μs, and the control period. Without waiting until later, the slave executes the command data synchronously after a certain communication delay, that is, after the set synchronization unit, and before the certain communication delay, that is, the data set before the control cycle. The master can acquire the slave information at the same timing before the synchronization unit as response data.

  Regarding the group 2 as well, by shifting the control processing start timing, transmission / reception timing, and command execution timing by the synchronization unit from the group 1, all slaves 2i (i = 5 to 8), communication data can be exchanged, and the communication delay between the master and the slave can be made constant by the set value of the synchronization unit without depending on the control cycle.

  FIG. 13 is a flowchart showing the communication initialization processing procedure of the synchronous communication method in the second master / slave synchronous communication system of the present invention. The processing shown in FIG. 6 corresponds to a plurality of groupings. Here, only a part different from the flowchart of FIG. 6 will be described.

  Steps S010 to S030 are the same as those in FIG.

In S040, whether or not communication timing allocation is possible is determined by equations (2 ′) and (7). If either of the expressions (2 ′) and (7) is not satisfied, error processing is performed in S041. Only when both formulas (2 ′) and (7) hold, communication timing assignment is possible, and the process proceeds to S050.

Total number of slaves ÷ Number of slaves that can communicate within a cycle ≤ Total number of cycles ... (2 ')
Number of group slaves j ÷ Number of slaves that can communicate within a cycle
≦ Number of synchronization unit cycles (7)

Total number of slaves: Sum of the number of slaves controlled by group j Total number of cycles = Least common multiple of control period j [μs] ÷ 125 [μs] (3 ')
125 μs: Isochronous cycle time defined in the IEEE 1394 standard Control cycle j: Control cycle of group j of control cycle data 11 Number of communication slaves j = Least common multiple of control cycle j ÷ Control cycle j
× Number of group slaves j
Number of group slaves j: Number of slaves controlled by group j Number of synchronization unit cycles = Synchronization unit [μs] ÷ 125 [μs]
(J = 1, 2,...: Group number)

  In S050, the transmission timing tables created in FIG. 6 are created for the number of groups.

Next, in S060, areas of the synchronous communication management table 14 for the total number of cycles calculated by the equation (3 ') are secured, cleared to 0, and the total number of cycles is set.

  In S070, the cycle used flags for the total number of cycles are secured and cleared to zero.

  In S080, the cycle used flag is searched from the head, and it is determined whether there is a continuous unused area for the transmission cycle (value on the left side of Expression (7)) used in the group. If not, error processing is performed in S041 and the process is terminated.

In S090, the slave assigned timing is extracted from the transmission timing table for each group, and 1 is added to the number of transmission slaves in the cycle of the synchronous communication management table 14 corresponding to the cycle obtained by adding the top cycle of the unused continuous area. Stores the slave number in the destination slave number. The process of S090 is repeated for all the slaves set in the group.

  In S100, the allocation results of all slaves in the group of the synchronous communication management table data are copied repeatedly for the total number of cycles in the control cycle, the cycle used flag of the copied cycle is set, and the slaves in the group are set in S110. Among them, the cycle used flag for the synchronization unit is set to used from the cycle in which the slave to be transmitted first is allocated.

In S120, as shown in Expression (8), the cycle in which the first slave to be transmitted in the group is allocated is set as the master group j control processing start timing.

Group j control processing start timing = MIN (slave transmission cycle # controlled by group j) (8)
(J = 1, 2,...: Group number)
MIN (A, B, C, ...): Minimum value in parentheses

  The processing from S080 to S120 is repeated for the number of groups.

  The processes in S130 and S140 are the same except that the value of the total number of cycles is the expression (3 ').

In S150, slave command execution timing and response creation timing for each group are calculated by equations (5 ′) and (6 ′), respectively.

Command execution timing = MOD ((Group j control processing start timing + number of synchronization unit cycles),
(Control cycle j number of cycles) (5 ')
Response creation timing = MOD ((reception allocation start cycle # + control period j cycle number -1),
(Control cycle j number of cycles) (6 ')
MOD (A, B): remainder of A by B (j = 1, 2,...: Group number)

  In S160, the command reception timing and response transmission timing for each slave are extracted from the synchronous communication management table 14 created in the above steps, and the number of cycles corresponding to the control cycle, command execution timing, and response creation timing data, In addition, it notifies all slaves in the group as a synchronous communication information data table.

The processing from S150 to S160 is repeated for the number of groups.
As described above, the synchronous communication management table 14 in FIG. 10 is created in the master 1 and the synchronous communication information data table 2 i 31 in FIG. 11 is created in each slave.

  The flowcharts showing the processing procedure when the cycle start packet is received after the master and slave synchronous communications are started are the same as those in FIGS.

According to the flowcharts of FIGS. 13, 7, and 8, the synchronous communication management table of FIG. 10 and the synchronous communication information data table of FIG. 11 are created from the control cycle data of FIG. Since communication can be performed according to the communication timing chart, even if the slaves to be controlled are divided into a plurality of groups, the master and all slaves can exchange control data within each control cycle, and within the control cycle Synchronous communication can be performed with a constant communication delay that is not dependent on the control cycle.

  As a third aspect of the present invention, an embodiment of automatic optimization of synchronization unit time will be described as a case where the number of slaves that can communicate in one isochronous cycle is four in the first embodiment of the present invention.

  FIG. 21 is a detailed view of the synchronous communication management table 14 according to the third embodiment of the present invention. In contrast to the synchronous communication management table of FIG. 3, the number of slaves allocated to one isochronous cycle has increased from two to four, so that there are four tables each for storing transmission / reception slave numbers, and slave S1 -S4 are all assigned to one isochronous cycle.

  FIG. 22 is a detailed view of the synchronous communication information data table 2i31 (i = 1 to 4) according to the third embodiment of the present invention. From the synchronous communication management table of FIG. 21, the synchronous communication information data tables of the slaves all have the same timing and therefore have the same value.

  FIG. 23 is a communication timing chart according to the third embodiment of the present invention. The master operates in accordance with the synchronous communication management table of FIG. 21, and each slave operates in accordance with the synchronous communication information data table of FIG. 22. In contrast to the operation of FIG. 5, communication with four slave stations is possible with one isochronous. Therefore, all slaves create response data at the timing of control cycle N-1 and cycle # 2, all slaves send responses at the timing of cycle # 3, and the master is all slaves at the timing of control cycle N + 1 and cycle # 0. The command data is transmitted, each slave receives the command data, and at the timing of cycle # 1, all slaves are changed to execute the command all at once.

Communication initialization processing procedure of the synchronous communication method showing a procedure of creating a synchronous communication management table used by the slave assignment unit 13 of the master for synchronous communication and a synchronous communication information data table used by the slave for the synchronous communication from the control cycle data 6 is the same as that in FIG. 6, and the difference will be described regarding the synchronization unit optimization.

  The same processing as in FIG. 6 is executed up to S120. In S130, first, the number of synchronization unit cycles used in Expression (4) is optimized by replacing it with the number of isochronous cycles to which the slave is actually allocated in the transmission timing table created in S050. In addition, the synchronization unit is changed to a time corresponding to the replaced number of synchronization unit cycles.

The same processing is performed after S140 by using a value obtained by replacing the synchronization unit cycle number with the optimized synchronization unit cycle number.

  Therefore, the synchronization unit in FIG. 2 can be optimized by shortening to 125 μs, which is the shortest, with respect to 250 μs in which the synchronization unit is set in advance, and can be operated with a shorter communication delay.

Similarly, when the number of isochronous cycles to which slaves are actually allocated in S050 exceeds the preset synchronization unit, the synchronization unit set in advance in S130 is optimized by extending the synchronization unit. It becomes possible to operate with a delay.

Here, when optimizing the number of synchronization unit cycles in S130, the optimization processing may be switched between execution and non-execution by setting with parameters or an inquiry to the user through an engineering tool.
Regardless of whether or not optimization is performed, the synchronization unit can be stored as data that can be read by a device such as an application program or an engineering tool to notify the user of the synchronization unit.

  As described above, in a master / slave synchronous communication system in which one master and one or more slaves are connected to the IEEE 1394 network and exchange communication data in synchronization with a control period of a predetermined time, communication timing is set for each group. Since communication data is exchanged in synchronization units that are less than or equal to the control period while shifting, even if the control period becomes longer, the communication delay is not affected and remains constant in the synchronization unit, so control performance can be improved. .

  Because the master and slave can communicate synchronously with the communication time required for communication between the master and slave transmission / reception data regardless of the control cycle setting, it takes time to create a control command that uses kinematics at the master. It can also be applied to applications such as robot control systems and motion control systems.

Configuration diagram of master-slave synchronous communication system showing an embodiment of the present invention Detailed view of control cycle data according to the first embodiment of the present invention Detailed view of the synchronous communication management table according to the first embodiment of the present invention. Detailed view of synchronous communication information data table according to the first embodiment of the present invention Communication timing chart according to the first embodiment of the present invention The flowchart which shows the communication initialization processing procedure of a synchronous communication system in the 1st master-slave synchronous communication system of this invention. The flowchart which shows the process sequence at the time of the cycle start packet reception after the synchronous communication start of a master in the master slave communication system of this invention The flowchart which shows the process sequence at the time of the cycle start packet reception after the synchronous communication start of a slave in the master-slave synchronous communication system of this invention Detailed view of control cycle data according to the second embodiment of the present invention Detailed view of synchronous communication management table according to the second embodiment of the present invention Detailed view of synchronous communication information data table according to the second embodiment of the present invention Communication timing chart according to the second embodiment of the present invention The flowchart which shows the communication initialization processing procedure of a synchronous communication system in the 2nd master-slave synchronous communication system of this invention The figure showing the format of the minimum form of the configuration ROM which the IEEE1394 equipment has The figure showing the format of the general form of the configuration ROM which the IEEE1394 equipment has The figure showing the format of bus_info_block The figure showing the format of CYCLE_TIME Detailed view of the communication timing management table applying the conventional method Communication timing chart using the conventional method Communication delay using conventional methods Detailed view of synchronous communication management table according to the third embodiment of the present invention Detailed view of synchronous communication information data table according to the third embodiment of the present invention Communication timing chart according to the third embodiment of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Master 11 Control period data 12 Slave detection part 121 Connection slave information 13 Slave allocation part 14 Synchronous communication management table 15 Cycle start packet reception process part 16 Command data transmission part 161 Command data 17 Response data reception part 171 Response data 18 Control process part 2i Slave 2i1 Command data reception unit 2i11 Command data 2i2 Response data transmission unit 2i21 Response data 2i3 Synchronous communication processing unit 2i31 Synchronous communication information data table 2i4 Cycle start packet reception processing unit 2i5 Response creation unit 2i6 Command processing unit 3 IEEE 1394 network Ci master 1 Command data from slave i to slave i Response data from slave i to master 1

Claims (8)

In a master-slave synchronous communication system in which one master and one or more slaves are connected to an IEEE 1394 network and the master and the slave communicate with each other in synchronization with a control cycle that is an integral multiple of an isochronous cycle.
In the case of reception from the slave, the master sets a synchronization unit that means a time in an isochronous cycle unit necessary for communication with all the slaves from the end of the control cycle, and transmits to the slave. In the case of, comprising a synchronous communication management table in which the synchronization unit is set from the beginning of the control cycle,
In the case of transmission to the master, the slave sets the synchronization unit from the end of the control period, and in the case of reception from the previous period master, the synchronous communication information in which the synchronization unit is set from the beginning of the control period. A master / slave synchronous communication system comprising a data table. The synchronous communication management table included in the master receives the timing at which the master starts control processing for creating command data to the slave, the number of slaves transmitted by the master, the slave number, and the master Holding the number of slaves and the slave number for each isochronous cycle;
The synchronous communication information data table provided in the slave includes the timing at which the slave receives command data from the master, the timing at which the command data is executed, and the timing at which response data to the master is created. Holding the timing of sending response data to the master,
The master / slave synchronous communication system according to claim 1. The slave allocation unit provided in the master is configured from the preset synchronization unit and the control period, the number of slaves communicating within the synchronization unit, and an array of slave numbers that uniquely specify the slave 2. The master / slave synchronization according to claim 1, wherein the synchronous communication management table is generated based on the control cycle data to be generated, and the synchronous communication information data table is generated based on the synchronous communication management table. Communications system. In accordance with the synchronous communication management table, the master executes the control process when it detects the timing to start the control process, performs reception when it detects the reception timing from the slave, and detects the transmission timing to the slave Then execute transmission,
According to the synchronous communication information data table, the slave receives the command data from the master when detecting the timing to receive the command data, and executes the processing of the command data when detecting the timing to execute the command data. The response data is created when the response data creation timing is detected, and the response data is sent to the master when the response data transmission timing is detected.
A master-slave synchronous communication system characterized by the above.   There are a plurality of the control cycles for communication between the master and the slave, the slaves are grouped for each control cycle, and the synchronization communication management table and the synchronization are shifted by shifting the control cycle by the synchronization unit for each group. 5. The master / slave synchronous communication system according to claim 1, wherein a communication information data table is created.   When the slave allocation unit creates a synchronous communication management table based on the previous period control cycle data, and detects an isochronous cycle in which communication is not performed within the previous period synchronization unit, the synchronization unit is shortened to an optimum value. The master-slave synchronous communication system according to any one of claims 1 to 5.   When the slave allocation unit in the previous period creates a synchronous communication management table based on the previous period control cycle data, the synchronization unit is extended to the optimum value if it detects that the communication time exceeds the previous period synchronization unit. The master-slave synchronous communication system according to any one of claims 1 to 5.   The master-slave synchronous communication system according to any one of claims 1 to 7, wherein the first-term master, the first-term slave, or the first-term master and the first-term slave notify the user of the optimized synchronization unit.

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