JP4961589B2 - Network system and slave synchronization method - Google Patents

Description

  The present invention relates to a network system in which a master and a plurality of slaves are connected by a communication line, and more particularly to a network system and a slave synchronization method for executing a synchronous operation of a plurality of slaves at an arbitrary timing.

In a conventional network system, a master such as a controller and a plurality of slaves are connected to a network and exchange data at a specific communication cycle.
FIG. 9 is a diagram showing communication data exchange in a conventional network system.
In FIG. 9, communication data is exchanged between a master and a slave in a specific communication cycle (S). Further, in order to provide real-time communication, the communication cycle (S) on the network is further divided into predetermined time slots (TS), and communication is performed with slave stations connected in units of these time slots. .
Further, in order to synchronize the slaves, a synchronization frame (SYNC) is issued from the master for each communication cycle, and the internal clocks of the slaves are synchronized when the synchronization frame is received.
When each slave receives data addressed to itself in a certain communication cycle, the received data is actually passed to the slave target device such as a servo drive or I / O at the timing when the next synchronization frame is received, and the slave control is performed. It is common to have a configuration that starts.
In general, the control cycle (T) of the host controller that is the master and the network communication cycle often operate asynchronously as shown in FIG. 9, so that the slave actually operates after the master outputs the command data. Until (communication waiting α) + (communication cycle S) occurs.

On the other hand, a controller connected to the network and one or more devices are provided with a global timer that is controlled via the network, and period control on the device side connected to the controller is performed using the global time indicated by the global timer. Some are configured to be synchronized (see, for example, Patent Document 1).
In addition, it is designed to synchronize multiple numerical control devices using time information distributed wirelessly, and to synchronize using time information distributed in common regardless of master / slave stations. There are some (see, for example, Patent Document 2).
Japanese Patent Laid-Open No. 2002-164872 Japanese Patent Laid-Open No. 2005-18605

In the conventional network system, since a plurality of slaves are operated in synchronization, each slave actually receives command data from the master, and then starts slave control when receiving a synchronization frame at the start of the next communication cycle. Although the control cycle of the host controller that is the master and the network communication cycle are often operating asynchronously as shown in FIG. 9, the slave operation is actually performed after the master outputs the command data. There is a problem that a delay of (communication synchronization waiting α) + (communication cycle S) occurs equally in all slaves until it is started.
The timing for synchronous execution of multiple slaves always depends on the communication cycle, which is the synchronization frame issuance timing. At other timings, the slave cannot be synchronously executed, and the synchronization is performed in a short time that is shorter than the communication cycle. There is a problem that it cannot be executed.

Also, for example, when considering a servo drive as an example of a slave target device, in the case of a system in which different types of servo drives are mixed and connected to the network, the axis operation is actually performed after a start command is input. The time until the start is different for each servo drive.
For this reason, in the case of a system in which different types of servo drives are mixed, even if each servo drive connected to the network starts synchronous execution at the timing when the synchronous frame is received, the actual operation starts. There is a problem that variations occur.
In addition, when there is a need to communicate asynchronously with slaves using a general-purpose network such as Ethernet (registered trademark), there is no reference synchronization frame, so real-time processing and synchronized execution of connected slaves There is also the problem that it is very difficult to do.
In addition, the invention described in Patent Document 1 requires a global timer for managing the global time in addition to the controller and the operation cycle timer that generates an actual control cycle for each slave station, which complicates the system configuration. There was a problem.
In the invention described in Patent Document 2, it is necessary to request the time information distributed from both the master and slave stations from the outside, and there is a problem that the system configuration becomes complicated.

  The present invention has been made in view of such problems, and in a network system in which a master and a plurality of slaves are connected by a communication line, it is possible to start synchronous execution of slaves at an arbitrary timing with a simple system configuration. In addition, even when different types of slaves are connected, these multiple slaves can be executed synchronously with high accuracy, and even in a network that performs asynchronous transmission and reception, a network that can execute synchronous execution The purpose is to provide a system.

In order to solve the above problem, the present invention is configured as follows.
According to the first aspect of the present invention, in a network system in which a master and a plurality of slaves communicate with each other in a prescribed time slot within a communication cycle, the master is grouped with one or more slaves that perform synchronization. And setting the synchronization start time for these groups, and every time command data output to the slave is performed, the time of the number of time slots multiplied by the time slot interval is subtracted from the synchronization start time for each group, A group execution start time management unit having a value as a new execution start time; and a start time setting unit for setting the execution start time in command data output to the slave, and the slave receives the time during communication. Receive time slot number measurement unit that measures the number of slots, and the target device in the slave that monitors time An execution start time monitoring unit for starting the execution of the operation, and the execution start time monitoring unit receives the time obtained by multiplying the number of time slots measured by the reception time slot number measuring unit by a time slot interval. The execution of the target device in the slave is started when the set time is reached by subtracting from the execution start time in the data.
Further, the invention according to claim 2 is the slave device control delay in which in the network system according to claim 1, the master stores a control delay time required for the slave to operate after receiving the command data. An information database is further provided, and each time the group execution start time management unit outputs command data to the slave, the synchronization start time for each group is subtracted by a time obtained by multiplying the number of time slots by a time slot interval. Further, the control delay time of the corresponding slave extracted from the slave device control delay information database is further subtracted, and the value is set as a new execution start time.
According to a third aspect of the present invention, in the network system according to the first aspect, a control delay time required for the slave to operate after receiving the command data is stored in the slave in advance. The master requests the control delay time from the slave, acquires the control delay time as a response from the slave, and each time the command execution data output to the slave is performed by the group execution start time management unit, the group And subtracting the time slot number multiplied by the time slot interval from each synchronization start time, further subtracting the control delay time of the corresponding slave, and setting the value as a new execution start time. To do.

According to a fourth aspect of the present invention, in the network system of the first aspect, the delay time for calculating the control delay time of the slave based on the number of IO points used in the slave and the setting status of the module. The master further includes a calculation unit, the master requests the control delay time from the slave, acquires the control delay time calculated by the delay time calculation unit as a response from the slave, and the group execution start time management unit Each time command data is output to the slave, the time of the number of time slots multiplied by the time slot interval is subtracted from the synchronization start time for each group, and the control delay time of the corresponding slave is further subtracted. This value is used as a new execution start time.
According to a fifth aspect of the present invention, in the network system according to the first aspect, the slave includes a timer measurement unit that measures time by a timer instead of the reception time slot number measurement unit. The start time monitoring unit subtracts the time measured by the timer measurement unit from the execution start time in the data received by the slave, and calculates a set time.
According to a sixth aspect of the present invention, in a network system in which a master and a plurality of slaves communicate asynchronously, a master timer measuring unit that measures time with a timer is provided between the master and the slave. Each time a transmission time measuring unit that measures transmission time and one or more slaves that perform synchronization, set a synchronization start time for these groups, each time command data output to the slave, The transmission time and the elapsed time measured by the master timer measurement unit are subtracted from the synchronization start time for each group, and the value is transmitted as a new execution start time to the slave. A start time setting unit is provided for setting the execution start time in the command data, and the slave measures time with a timer. A timer measurement unit, and an execution start time monitoring unit that monitors the time and controls the operation execution of the target device in the slave, the execution start time monitoring unit, the time measured by the timer measurement unit, Subtracting from the execution start time in the data received by the slave, the operation execution of the target device in the slave is started when the set time is reached.

The invention according to claim 7 is the slave synchronization method of the network system in which the master and the plurality of slaves communicate with each other in a specified time slot within a communication cycle, wherein the master performs one or more synchronization executions. The slaves are grouped, the synchronization start time of each group is set, and each time command data is output to the slave, the time is calculated by multiplying the number of time slots by the time slot interval from the synchronization start time for each group. The value is subtracted and output to the slave as a new execution start time. The slave subtracts the time obtained by multiplying the number of time slots by the time slot interval from the execution start time in the data received by the slave. And starting the execution of the operation of the target device in the slave at the set time. To do.
The invention according to claim 8 is the slave synchronization method of the network system according to claim 7, wherein the master stores a control delay time required for the slave to operate after receiving the command data. Each time command data is output to the slave, the time of the number of time slots is multiplied by the time slot interval from the synchronization start time for each group, and the control delay time of the corresponding slave is further subtracted. This value is used as a new execution start time.
The invention according to claim 9 is the slave synchronization method of the network system according to claim 7, wherein a control delay time required for the slave to operate after receiving the command data is stored in the slave in advance. The master requests the control delay time from the slave, acquires the control delay time as a response from the slave, and starts the synchronization for each group each time command data is output to the slave. The time is subtracted by the time obtained by multiplying the number of time slots by the time slot interval, and the control delay time of the corresponding slave is further subtracted to set the value as a new execution start time.

The invention according to claim 10 is the slave synchronization method of the network system according to claim 7, wherein the slave has its own control delay time based on the number of IO points used by the slave and the setting status of the module. The master requests the control delay time from the slave, acquires the control delay time calculated by the slave as a response from the slave, and performs command data output to the slave each time, Subtracting the time slot number multiplied by the time slot interval from the synchronization start time for each group, further subtracting the control delay time of the corresponding slave, and setting the value as a new execution start time It is what.
The invention according to claim 11 is the slave synchronization method of the network system according to claim 7, wherein the slave subtracts the time measured by itself from the execution start time in the data received by the slave. The set time is calculated.
The invention according to claim 12 is a slave synchronization method of a network system in which a master and a plurality of slaves communicate asynchronously, wherein the master groups each of the one or more slaves that perform synchronization, Set the synchronization start time for each group, measure the transmission time required for communication between the master and the slave, measure the elapsed time of the master, and output the command data to the slave The transmission time and the elapsed time are subtracted from each synchronization start time, and the value is output as a new execution start time to the slave, and the slave receives the time measured by itself as data received by the slave. The execution start of the target device in the slave is started when the set time is reached. It is an.

  According to the first, fifth, seventh, and eleventh aspects of the present invention, one or more slaves that execute synchronization are grouped into the master, and the synchronization start time for these groups is set, and command data output to the slaves Each time, the group execution start time management unit that subtracts the time slot number multiplied by the time slot interval from the synchronization start time for each group and uses the value as the new execution start time, and the command to be output to the slave It has a start time setting unit that sets the execution start time in the data, and monitors the time with a reception time slot number measurement unit that measures the number of time slots received during communication or a timer measurement unit that measures time. An execution start time monitoring unit for starting operation execution of the target device in the slave, and the execution start time monitoring unit counts the number of time slots. Since the time measured by the timer slot or the time measured by the timer measurement unit is subtracted from the execution start time in the data received by the slave, the execution of the operation of the target device in the slave is started when the set time is reached. With a simple system configuration, it is possible to specify the time from when the slave receives data until it actually operates, and to receive synchronization frames issued in the next network cycle to synchronize each slave so far The slave can start synchronous execution at any timing for the slave operation that was performing the payout operation at the timing.

According to the second to fourth and eighth to tenth aspects of the present invention, in consideration of the control delay time required for the slave to operate after receiving the command data, the group execution start time management unit outputs the command data to the slave. Is subtracted by the time slot number multiplied by the time slot interval from the synchronization start time for each group, and the control delay time of the corresponding slave is further subtracted to obtain the new execution start time. Therefore, even if the connected slaves are not of the same type, the execution start times of the slaves can be matched.
As a result, if the target slave device is a servo drive, the actual axis operation can be performed in synchronism with very accurate timing at the time of actual output if it is related to I / O.

  According to the inventions of claims 6 and 12, in a network system in which a master and a plurality of slaves communicate asynchronously, a master timer measuring unit that measures time by a timer and a transmission time between the master and the slave. Set the transmission time measurement unit to be measured and one or more slaves that perform synchronization as a group, set the synchronization start time for each group, and start synchronization for each group each time command data is output to the slave. The transmission time and the elapsed time measured by the master timer measurement unit are subtracted from the time, and the group execution start time management unit using the value as a new execution start time, and the execution start time in the command data transmitted to the slave. It has a start time setting unit to set, and a slave timer measurement unit that measures time with a timer, and monitors the time, the slave An execution start time monitoring unit that controls the operation execution of the target device in the device, and the execution start time monitoring unit subtracts the time measured by the timer measurement unit from the execution start time in the data received by the slave. Since the operation execution of the target device in the slave is started at the time, it is possible to execute the synchronization even in a network that performs transmission / reception by asynchronous communication.

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

FIG. 1 is a block diagram showing a network system of the present invention.
In FIG. 1, 1 is a master, and 11a to 11e are slaves, and have an execution start time monitoring unit 12 for monitoring execution time and a reception time slot number measuring unit 16 for measuring time slots to be received (note that The slave may be simply referred to as 11).
The master 1 includes a network output unit 2 that outputs data to the network and a calculation unit 6 that performs data calculation.
The network output unit 2 includes execution start time management units 3 a and 3 b that manage the execution start time of the slave 11.
The slaves 11 are grouped and managed for each of the plurality of slaves 11 to be synchronized. Since an example classified into two groups is shown, there are two execution start time management units for the first and second groups.
4 is a start time setting unit for setting the execution start time of the slave 11 every time data is output to the communication IF memory, and 5 is a communication IF memory for communication.
In the calculation unit 6, there are a CPU 7 and an application 8. Further, there is a slave device control delay information database 9 as a database in which the control delay time of each slave device is stored because the types of slave devices are different. If the slave device is the same model, the slave device control delay information database 9 is not used.
A plurality of slaves 11 that are synchronized are grouped. In the case of the example of FIG. 1, a first group is formed by 11a to 11c, and a second group is formed by 11d to 11e. In addition, although the case where there are two groups is illustrated in FIG. 1, it is not limited to two.

Next, the details of the synchronization method in the present invention will be described.
FIG. 2 is a flowchart showing the processing procedure of the master in the slave synchronization method of the present invention.
First, in step S1, slaves 11 that perform synchronous execution are grouped together using a keyboard (not shown) of master 1 and set as a group.
Next, in step S2, the synchronization start time TGno (no: number of groups) of each group is set. This synchronization start time is a value with the time when the master outputs the command value of the first slave of the group as 0. The start time TGno is determined according to the priority of the output of the slave 11.
That is, when it is desired to start synchronization of the slave 11 as soon as possible after outputting the command data, the synchronization start time TGno is set to a value smaller than the communication cycle.

FIG. 3 is a diagram showing exchange of communication data in the network system of the present invention.
In this example, the first group of the first slave 11a to the third slave 11c is set to a value shorter than the communication cycle S as TG1 in order to perform synchronization execution as soon as possible. In addition, the synchronization start time TG2 of the second group configured by the fourth slave 11d and the fifth slave 11e is set longer than the communication cycle S.
In FIG. 3, the communication cycle S is divided into five time slots, and for each time slot, the command from the master 1 is transmitted in order from the first slave 11a, and the slave 11 returns a response.

Returning to the description of FIG. 2, in step S3, the calculation order of the slaves 11 to be output is determined in the order of the synchronization start time TGno, and in step S4, the master 1 calculates the command data to each slave 11.
Next, at step S5, the first and second group execution start time management units 3a and 3b hold the synchronization start time TGno for each group and output data to the communication IF memory 5 as follows. Is calculated for each group.
RT = synchronization start time TGno−time slot interval TS · n
(N: Number of timeslots within the communication cycle. Cleared when the communication cycle is reached)
This execution start time means the remaining time until the time set as the synchronization start time, and the execution start time is calculated by the slave 11 as described later, and the execution is started when the value becomes zero.
For example, when the time slot interval is 2 ms and the communication cycle is 10 ms, TG1 of the first group is 6 ms. In the first time slot, RT = 6-2 · 1 = 4, and in the second time slot, RT = 6-2 · 2 = 2.
Next, in step S6, the start time setting unit 4 sets the execution start time RT as command data to the slave 11, and then writes it in the communication IF memory 5 and outputs it to the slave 11.
Next, in step S7, it is checked whether the command data of all the slaves 11 has been output. If the output has been completed, the process returns to step S4 to calculate the next command data. If the output has not ended, the process proceeds to step S8 to wait for the elapse of the time slot time. Then, after the elapse of time, the process proceeds to step S9 and 1 is added to the time slot number, and the process proceeds to step S5.

Next, a procedure for the slave 11 to start execution in synchronization will be described.
FIG. 4 is a block diagram showing the configuration of the slave 11 of the network system of the present invention. Reference numeral 12 denotes an execution start time monitoring unit, 13 a CPU, 14 a data receiving unit, 15 a receiving buffer, 17 a data transmitting unit, 18 a transmitting buffer, and 19 a target slave device such as a servo drive.
Reference numeral 16 denotes a reception time slot number measuring unit which measures the number of time slots received during communication with reference to the received synchronization frame.
In the slave 11, the command data from the master 1 is received by the data receiving unit 14 and stored in the reception buffer 15.
The execution start time monitoring unit 12 subtracts the time obtained by multiplying the number of time slots acquired by the reception time slot number measuring unit 16 by the time slot interval from the execution start time RT set in the command data, and reaches the set time. Then, the data is transferred to the CPU 13 of the slave 11 and the execution of the target slave device 19 is started.
For example, referring to FIG. 3, when the time slot is 2 ms and the communication cycle is 10 ms, TG1 of the first group is 6 ms.
The first slave 11a receives RT = 4 as a command in the first time slot. RT is subtracted by the execution start time monitoring unit 12 in the first slave 11a in the second time slot, RT = 2, and 0 in the third time, so that it can be determined that the set time has been reached.
The second slave 11b receives RT = 2 as a command in the second time slot. In the third time slot, the execution start time monitoring unit 12 in the second slave 11b subtracts RT, RT = 0, and the set time is reached.
The third slave 11c receives RT = 0 as a command in the third time slot.
As described above, all the slaves 11 in the first group from the first slave 11a to the third slave 11c reach RT = 0 in the third time slot, reach the set time, and start executing synchronously in 6 ms from the synchronization frame. .

Next, as a second embodiment, a case where the target slave devices are of different types will be described.
The operation will be described below with a focus on differences from the first embodiment.
First, the slave device control delay information database 9 is set to be used by a keyboard or the like (not shown) of the master 1 in FIG.
FIG. 5 shows an example of data set in the slave device control delay information database 9. Here, it is shown that the No. 1 model has a control delay time of 1.5 ms, the No. 2 model has a 2.4 ms control, and the No. 3 model has a 3.0 ms control delay time (SLns, ns is the model number) compared to the standard model.
When the master 1 outputs to each slave 11, the value is set in consideration of the control delay time SLns in each slave device.
That is, in step S5 of FIG. 2, the first and second group execution start time management units 3a and 3b manage the synchronization start time TGno for each group and the control delay time SLns of the slave 11 in the group as the slave. The execution start time RT is calculated by the following procedure every time it is acquired from the device control delay information database 9 and output to the communication IF memory 5.
RT = synchronization start time TGno−control delay time SLns−time slot interval TS · n
(N: Number of timeslots within the communication cycle. Cleared when the communication cycle is reached)
Instead of having the slave device control delay information database 9 in the master 1, it is possible to store the control delay time in each slave 11 and return a response of the control delay time to the request from the master 1.
The slave 11 may be provided with a delay time calculation unit (not shown) for calculating the delay time, and the delay time may be calculated by the number of IO points used by the slave 11 and the module setting status. . In this case, when the master 1 outputs a request for the control delay time to the slave 11, the delay time calculation unit of the slave 11 calculates its own control delay time and returns a response.
In this way, by outputting the command data in consideration of the control delay time of each slave 11, even when different types of slaves 11 perform synchronous execution, it is possible to match the actual operations with high accuracy. It becomes possible.

Next, as a third embodiment, an example in which the time of the slave 11 is measured using a timer will be described. The operation will be described below with a focus on differences from the first embodiment.
FIG. 6 is a block diagram showing the configuration of the slave 11 of the third embodiment of the network system of the present invention. A timer measurement unit 20 is provided instead of the reception time slot number measurement unit 16 of FIG.
The execution start time monitoring unit 12 measures the elapsed time with the timer measurement unit 20 based on the time when the data addressed to itself is received, and receives it at the slave CPU 13 when the execution start time RT set in the command data is reached. Pass data and start execution.
With the above configuration, the slave 11 only needs to measure the relative time after receiving the command data. Therefore, the measurement time of the timer is short, and the global time as described in Patent Document 1 is used. Compared to the case with a timer, sufficient accuracy can be secured with its own timer accuracy.

Next, as a fourth embodiment, a case will be described in which asynchronous communication such as general Ethernet (registered trademark) is used as a network environment for communication.
The operation will be described below with a focus on differences from the first embodiment.
FIG. 7 is a block diagram showing a fourth embodiment of the network system of the present invention.
First, a network is configured using the switching hub 21 so that unnecessary traffic other than communication between the master 1 and the slave 11 does not occur. Since there is no time slot because it is asynchronous, the master 1 is provided with a master timer measuring unit 23 for measuring the elapsed time T (i), and the time for outputting data to each slave 11 is calculated. In addition, it has a transmission time measuring unit 22 that measures the time required for transmission.

FIG. 8 is a flowchart showing the processing procedure of the master in the fourth embodiment of the slave synchronization method of the present invention.
In step S11, the slaves 11 that perform synchronization are grouped together using a keyboard (not shown) of the master 1 and set as a group.
Next, in step S12, the synchronization start time TGno (no: number of groups) of each group is set.
Next, in step S13, the calculation order of the slaves 11 that perform output in the order of the synchronization start time TGno is determined. In step S14, the transmission time measuring unit 22 measures the time Lt (n) required for communication between the master 1 and the slave 11. For example, a PING (Packet Internet Grouper) command or the like can be used for this transmission time measurement.
In step S15, the operation of the master timer measuring unit 23 for measuring the elapsed time T (i) is started. In step S <b> 16, the master 1 calculates command data for each slave 11.
Next, in step S17, the first and second group execution start time management units 3a and 3b manage the synchronization start time TGno for each group and output data to the communication IF memory 5 as follows. The execution start time RT is calculated for each group.
RT = start time TGno−transmission time Lt (n) −elapsed time T (i)
Next, in step S18, the start time setting unit 4 sets the execution start time RT as command data to the slave 11, and then writes it in the communication IF memory 5 and outputs it to the slave 11.
Next, in step S19, it is checked whether the command data of all slaves 11 has been output. If the output has not ended, the process proceeds to step S17. If the output has been completed, the elapsed time T (i) is reset in step S20, and the process returns to step S16.
The execution start time monitoring unit 12 of the slave 11 measures the elapsed time by the timer measurement unit 20 with reference to the time when the data addressed to the own station is received, and when the execution start time RT set in the command data is reached, The received data is passed to the CPU 13 to start execution.
In this way, the command data output time and slave execution start time are managed in the master network output unit, so that synchronous execution with multiple slaves can be performed while maintaining real-time performance using a general-purpose network. It becomes possible.

The block diagram which shows the network system of this invention The flowchart which shows the processing procedure of the master of the slave synchronization method of this invention The figure which shows exchange of the communication data of the network system of this invention The block diagram which shows the structure of the slave of the network system of this invention Example of data set in the slave device control delay information database The block diagram which shows the structure of the slave of 3rd Example of the network system of this invention The block diagram which shows the 4th Example of the network system of this invention The flowchart which shows the process sequence of the master of the 4th Example of the slave synchronization method of this invention. Diagram showing communication data exchange in a conventional network system

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Master 2 Network output part 3a, 3b 1st, 2nd group execution start time management part 4 Start time setting part 5 Communication IF memory 6 Calculation part 7, 13 CPU
8 Application 9 Slave device control delay information database 10 Networks 11a to 11e First to fifth slaves 12 Execution start time monitoring unit 14 Data reception unit 15 Reception buffer 16 Reception time slot number measurement unit 17 Data transmission unit 18 Transmission buffer 19 Target slave Device 20 Timer measurement unit 21 Switching hub 22 Transmission time measurement unit 23 Master timer measurement unit 30 Ethernet (registered trademark)

Claims (12)

In a network system in which a master and a plurality of slaves communicate with each other in a specified time slot within a communication cycle,
One or more slaves that perform synchronization are grouped into the master, the synchronization start time for these groups is set, and each time command data is output to the slave, the synchronization start time for each group A group execution start time management unit that subtracts the time slot number from the time slot multiplied by the time slot and sets the value as a new execution start time,
A start time setting unit for setting the execution start time in the command data output to the slave;
In the slave, a reception time slot number measuring unit that measures the number of time slots received during communication,
An execution start time monitoring unit that monitors time and starts operation execution of the target device in the slave,
The execution start time monitoring unit subtracts a time obtained by multiplying the number of time slots measured by the reception time slot number measuring unit by a time slot interval from the execution start time in the data received by the slave, and sets the set time. The network system is characterized in that the execution of the operation of the target device in the slave is started at that time. The master further comprises a slave device control delay information database storing a control delay time taken until the slave operates after receiving the command data.
Each time the group execution start time management unit outputs command data to the slave, it subtracts a time slot number multiplied by a time slot interval from the synchronization start time for each group, and the slave device control delay 2. The network system according to claim 1, wherein the control delay time of the corresponding slave extracted from the information database is further subtracted to set the value as a new execution start time. Store in advance the control delay time required for the slave to operate after receiving the command data,
The master requests the control delay time from the slave, acquires the control delay time as a response from the slave,
Each time the group execution start time management unit performs command data output to the slave, the synchronization start time for each group is subtracted from the time slot number multiplied by the time slot interval, and the corresponding slave's 2. The network system according to claim 1, wherein the control delay time is further subtracted to set the value as a new execution start time. Based on the number of IO points used in the slave and the setting status of the module, the slave further includes a delay time calculation unit that calculates its own control delay time,
The master requests the control delay time from the slave, acquires the control delay time calculated by the delay time calculation unit as a response from the slave,
Each time the group execution start time management unit performs command data output to the slave, the synchronization start time for each group is subtracted from the time slot number multiplied by the time slot interval, and the corresponding slave's 2. The network system according to claim 1, wherein the control delay time is further subtracted to set the value as a new execution start time. The slave includes a timer measurement unit that measures time by a timer instead of the reception time slot number measurement unit,
The network according to claim 1, wherein the execution start time monitoring unit subtracts the time measured by the timer measurement unit from the execution start time in the data received by the slave, and calculates a set time. system. In a network system in which a master and multiple slaves communicate asynchronously,
In the master, a master timer measuring unit that measures time by a timer,
A transmission time measuring unit for measuring a transmission time between the master and the slave;
One or more slaves that perform synchronization are grouped, and a synchronization start time is set for these groups, and each time command data is output to the slave, the transmission time is determined from the synchronization start time for each group. And a group execution start time management unit that subtracts the elapsed time measured by the master timer measurement unit and sets the value as a new execution start time,
A start time setting unit for setting the execution start time in the command data transmitted to the slave;
In the slave, a timer measuring unit that measures time by a timer, and
An execution start time monitoring unit for monitoring time and controlling operation execution of the target device in the slave,
The execution start time monitoring unit subtracts the time measured by the timer measurement unit from the execution start time in the data received by the slave, and executes the operation of the target device in the slave at a set time. A network system characterized by starting a network. In a slave synchronization method of a network system in which a master and a plurality of slaves communicate with each other in a specified time slot within a communication cycle,
The master is a group of one or more slaves that perform synchronization,
Set the synchronization start time for each group,
Every time the command data output to the slave is performed, the time of the number of time slots multiplied by the time slot interval is subtracted from the synchronization start time for each group, and the value is output to the slave as a new execution start time,
The slave subtracts the time obtained by multiplying the number of time slots by a time slot interval from the execution start time in the data received by the slave,
A slave synchronization method for a network system, wherein operation execution of a target device in the slave is started at a set time. In the master, the control delay time required for the slave to operate after receiving the command data is stored,
Each time the command data is output to the slave, the time of the number of time slots multiplied by the time slot interval is subtracted from the synchronization start time for each group, and the control delay time of the corresponding slave is further subtracted, 8. The network system slave synchronization method according to claim 7, wherein the value is set as a new execution start time. Store in advance the control delay time required for the slave to operate after receiving the command data,
The master requests the control delay time from the slave, acquires the control delay time as a response from the slave,
Each time the command data is output to the slave, the time of the number of time slots multiplied by the time slot interval is subtracted from the synchronization start time for each group, and the control delay time of the corresponding slave is further subtracted. 8. The network system slave synchronization method according to claim 7, wherein the value is set as a new execution start time. The slave calculates its own control delay time based on the number of IO points used by the slave and the setting status of the module,
The master requests the control delay time from the slave, acquires the control delay time calculated by the slave as a response from the slave,
Each time the command data is output to the slave, the time of the number of time slots multiplied by the time slot interval is subtracted from the synchronization start time for each group, and the control delay time of the corresponding slave is further subtracted. 8. The network system slave synchronization method according to claim 7, wherein the value is set as a new execution start time.   8. The slave synchronization method for a network system according to claim 7, wherein the slave subtracts the time measured by itself from the execution start time in the data received by the slave to calculate a set time. In a slave synchronization method of a network system in which a master and a plurality of slaves communicate asynchronously,
The master groups each of the one or more slaves that perform synchronization,
Set the synchronization start time for each group,
Measure the transmission time taken to communicate between the master and the slave,
Measure the elapsed time of the master,
Every time command data output to the slave, the transmission time and the elapsed time are subtracted from the synchronization start time for each group, the value is output to the slave as a new execution start time,
The slave subtracts the time measured by itself from the execution start time in the data received by the slave,
A slave synchronization method for a network system, wherein operation execution of a target device in the slave is started at a set time.

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