JP4032646B2 - Network time adjustment method and control system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a time synchronization method, and in particular, a remote I / O network (master-remote network) for synchronizing the time of each station in a remote I / O system used for communication between computers and programmable controllers. Regarding the method.
[0002]
[Prior art]
There are various types of systems, a stand-alone method in which all the controls are performed by a single controller without using a network, and multiple controllers are distributed and connected via a network. The master-local system that constitutes one control system has only one controller, and the input / output devices that are the limbs are connected to the network, and the system is classified into the master-remote system that enables distributed arrangement. .
[0003]
Conventionally, as a standard control system that performs control using a programmable controller (hereinafter referred to as a PC), a master-remote system is utilized as shown in FIG.
FIG. 8 is a system configuration diagram showing a configuration of a PC control system employing a remote I / O network that is a master-remote system.
The remote I / O network includes a remote master station and a plurality of remote I / O stations. For convenience, the unit configuration on the remote master station side is referred to as a master system, and the unit configuration on the remote I / O station side is referred to as a subsystem. To do.
In the figure, 101 is a master system, 102 is a subsystem, 103 is a transmission cable for connecting each system, and 104 is a termination resistor that is essential when the transmission cable 103 is a coaxial bus system.
[0004]
The master system 101 includes a controller 111 that controls a system configured by a remote I / O network, a power supply unit 112 that supplies power to the master system, digital information (ON / OFF) and analog information (current) connected to the outside. Non-intelligent unit 113 that performs input / output of / voltage / temperature / pressure, etc., intelligent unit 114 that performs serial communication services with external devices, network function services, positioning processing, BASIC operations, etc., and remote I / O network control The remote master station 115 is configured.
Similarly, the subsystem 102 includes a power supply unit 122, a non-intelligent unit 123, and a remote I / O station 125.
[0005]
Next, a schematic operation of a control system that employs a remote I / O network will be described.
In the case of the master-remote system, there is only one controller although various devices are distributed.
For this reason, the remote I / O station 125 system and the remote master station 115 system need to be distributed and coordinated.
Therefore, the terms “master system” and “subsystem” are defined for the sake of convenience in the sense that the system is composed of a master system + Σsubsystem.
In this standard control system, one master system and three sub-systems constitute one control system, and the three sub-systems have station numbers (1, 2, 3 in this case) assigned to remote I / O stations. Is uniquely identified, and since there is only one master system, station number 0 is given.
[0006]
The remote master station 115 performs communication control of the remote I / O network, transmits control information generated in the master system to each subsystem, and controls generated in the subsystem transmitted from the remote I / O station 125. Receive information. Further, the most important role is to control the transmission timing of the remote master station itself and each remote I / O station.
On the other hand, the remote I / O station 125 supervises the sub-system of the own station and transmits control information generated in the sub-system to the master system or control generated in the master system transmitted from the remote master station. Receive information.
[0007]
FIG. 9 shows a transmission frame used when the remote master station 115 and the remote I / O station 125 transmit and receive.
Since the master system and the subsystem are connected to each other by a single transmission cable 103, a common transmission frame format is required. In this transmission frame, a transmission indicating a target station number and a transmission source to be transmitted is included. There are fields for storing the original station number, a command indicating the content of transmission, and data to be transmitted.
[0008]
FIG. 10 shows the control information exchange timing between the remote master station 115 and the remote I / O station 125.
Since the master system and the subsystem are connected to each other by a single transmission cable, if each station transmits without permission, the transmission data collides and transmission is not performed correctly.
Therefore, the remote master station 115 controls the order of transmission.
FIG. 10 shows an image in which the remote master station 115 first transmits, and then the remote I / O station 125 transmits in the station number order.
When each station finishes transmitting once, one cycle of communication (defined as one link scan) ends, and the time required for one link scan is defined as one link scan time.
[0009]
[Problems to be solved by the invention]
Since the subsystem of the remote I / O station 125 is merely a limb of the system in its role, only the non-intelligent unit was originally mounted on the remote I / O station side.
However, in recent years, the design philosophy of distributed control has become popular, and a system configuration in which only a controller and a remote master station are arranged on the master system side and an intelligent unit and a non-intelligent unit are installed on the subsystem side is becoming mainstream. As a result of this change, the opportunity to connect intelligent units such as positioning units, BASIC operation units, and serial communication service units to remote I / O stations has increased.
Here, the positioning unit (records the positioning start time and the time when the error occurred), the BASIC operation unit (adds the time (time stamp) to the BASIC program file), the serial communication service unit (a serious abnormality occurs in the system) In order to perform all the functions of the intelligent unit, such as notifying the system administrator of the content and time of occurrence of the system abnormality via a serial communication line, the clock information is necessary. As described above, the remote I / O station side does not have a clock circuit due to its nature, and means for transmitting clock information to the remote I / O station side also in the remote I / O network. There was no.
Since only the non-intelligent unit 123 was originally mounted on the remote I / O station side, it was not necessary to transmit clock information to the remote I / O station side.
In other words, in the conventional remote I / O network, the clock information is not provided to the remote I / O station side, so that the clock information service function using the clock information can be realized in the remote I / O system. There wasn't.
[0010]
An object of the present invention is to make it possible to realize a clock information service function even in a remote I / O system.
Another object of the present invention is to transmit a clock information service function to a local station and set clock information in a control system uniquely.
[0011]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides a remote master station connected to a controller adopting a refresh method via a system bus, and connected to the remote master station via a network and controlled by the remote master station. a Contact Keru time setting method of a network control system that includes a remote I / O station which is, above the remote master station, the clock information received from the controller, in synchronization with the END timing of the controller described above and transmitting to the remote I / O station, the remote I / O station, upon receiving the clock information, to correct the transmission delay of the link scan time content, the remote I / O station and the system bus , providing a corrected clock information to the units connected via is intended to include.
[0015]
Further, in the control system in which the master station and the local station are connected via a network, the master station transmits the clock information received from the controller via the connected system bus to the local station; When the local station receives the clock information, the local station includes a step of correcting the transmission delay corresponding to the link scan time with respect to the clock information received from the master station and correcting the clock information of the local station itself. is there.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Embodiment 1 FIG.
Embodiments of the present invention will be described below with reference to FIGS.
FIG. 1 is an example of a control system configuration of a PC adopting a remote I / O network according to an embodiment of the present invention. Based on the design concept of distributed control, only the controller is arranged on the remote master station side forming the master system. A system configuration in which a non-intelligent unit and an intelligent unit are mounted on the remote I / O station side forming a plurality of subsystems is configured.
In the figure, 1 is a master system, 2 is a sub-system, 3 is a transmission cable for connecting each system, and 4 is a termination resistor that is essential when the transmission cable 3 is a coaxial bus system.
[0018]
The master system 1 includes a controller 11 that controls a system configured with a remote I / O network, a power supply unit 12 that supplies power to the master system, and a remote master station 15 that controls the remote I / O network.
The subsystem 2 includes a power supply unit 22 that supplies power to the subsystem, a non-intelligent unit 23, an intelligent unit 24 that performs serial communication services with external devices, network function services, positioning processing, BASIC operations, and the like, and a remote I / O station 25.
[0019]
FIG. 2 shows a transmission frame used at the time of transmission / reception by the remote master station and each remote I / O station in the present invention.
Although the transmission frame body is not changed from the conventional example, “1: clock information” is defined in the command field of the frame, and clock information corresponding to the clock information is added to the data field.
Here, the clock information can store information up to the year, month, day, hour, minute, second, 1/10 second, 1/100 second, 1/1000 second, day of the week.
[0020]
FIG. 3 shows the exchange timing of control information between the remote master station and the remote I / O station in the present invention.
In the figure, the difference from FIG. 10 shown in the conventional example is that the remote master station transmits clock information to all stations at the end of the link scan, and each remote I / O station receives the clock information at the same time. It is.
[0021]
Usually, the controller 11 is related to an external input / output operation (hereinafter referred to as input / output refresh), with respect to the control cycle (control program calculation cycle) of the controller 11 itself, the control cycle end timing (hereinafter referred to as END timing). ) Implements two methods: a refresh method that performs batch input / output refresh with the outside, and a direct method that performs input / output refresh at the timing described in the user's program.
In the refresh method, output → input is performed at the END timing, and the next control cycle is started. Therefore, since the input / output refresh is performed collectively, the control cycle is shortened and the system throughput can be improved. However, there is a time lag between the timing of the input / output refresh and the timing of operating the information of the external device described in the user program (because the input / output refresh is performed collectively at the END timing).
On the other hand, the direct method is different from the refresh method in that there is no time lag between the timing of the input / output refresh and the timing of manipulating the information of the external device described in the user program, but it frequently occurs during the control cycle. Therefore, the system throughput may be reduced.
[0022]
In the embodiment of the present invention, the reason why the remote master station transmits to all clock information stations at the end of the link scan and each remote I / O station receives the clock information at the same time is the input / output refresh timing of the controller. Is related.
In other words, “high throughput” is one of the elements required for control systems in recent years, and shortening of the control cycle of the controller is required to realize this, and the above refresh method is inevitably adopted. It's getting on.
By adopting the refresh method, data exchange with the outside is performed at the END timing, and as a result, the system operates in synchronization with the END timing.
[0023]
In the case of a remote I / O network, the event corresponding to the END timing of the controller is “link scan end timing”, and it is desirable that the controller and the remote I / O network operate synchronously.
Since the controller repeats the operation of “program operation completion → output to remote I / O network → input from remote I / O network → program operation start”, the remote I / O network is synchronized with the END timing of the controller. As a result, the entire system can be synchronized with the END timing.
[0024]
Furthermore, since the next link scan starts with “link scan end timing” as a trigger, it can be considered that “link scan end timing” = “link scan start timing”.
Therefore, in this embodiment, the clock information is distributed at this timing corresponding to the END timing of the controller.
[0025]
FIG. 4 shows a time adjustment method for a remote I / O network according to the present invention.
On the master system side in the figure, 10 is a system bus for exchanging data between the controller 11 and the remote master station 15 or the remote master station 25, and 31 is a bus I / F for exchanging data with the system bus 10. , 32 are clock circuits included in the controller 11 and have clock information. The clock circuit 32 usually has a programming tool dedicated to the controller. The user stores the clock information in the clock storage area 32A with the tool, and the clock information is updated by the clock circuit 32B.
41 is a bus I / F for exchanging data with the system bus 10, 42 is a clock storage area for storing clock information transferred to the remote master station 15 via the system bus 10, and 43 is a transmission buffer 43A. The transmission I / F has a reception buffer 43B and performs transmission processing.
[0026]
On the subsystem side in the figure, 20 is a system bus for exchanging data between the remote I / O station 25 and the intelligent unit 23 and the non-intelligent unit 24, and 51 is a bus for exchanging data with the system bus 20. I / F 52 is a link scan measuring circuit for monitoring the link scan time, 53 has a transmission buffer 53A and a reception buffer 53B, and interprets a command on a transmission frame transmitted from the master station 53C. And a transmission I / F for performing transmission processing.
61 is a bus I / F that exchanges data with the system bus 20 in the intelligent unit 23, and 71 is a bus I / F that exchanges data with the system bus 20 in the non-intelligent unit 24.
[0027]
The controller 11 continuously executes a control program created by the user to control the system, and has a time (calculation time) required for executing the program, that is, a control cycle.
Clock information is written from the clock storage area 32A to the clock storage area 42 of the remote master station 15 via the system bus 10 at each control cycle (more precisely, END timing).
At that time, the clock information is transferred in the order of the bus I / F 31 of the controller 11 → the system bus 10 → the bus I / F 41 of the remote master station 15 → the clock storage area 42 of the remote master station 15.
Here, since the remote master station 15 is a unit for which the communication I / F is a work and is not a control unit, the remote master station 15 has only a clock circuit only by obtaining clock information from the controller 11. Absent.
[0028]
FIG. 5 is a flowchart showing the clock information transmission process of the remote master station.
As shown in FIG. 3, the control information exchange timing between the remote master station 15 and the remote I / O station 25 in the present invention is as follows. If detected (step S1), the clock information is read from the clock storage area 42 built in itself (step S2), the clock information is transmitted (step S3), and then the control information of the remote master station 15 is transmitted (step S3). S4).
[0029]
FIG. 6 is a flowchart showing processing on the remote I / O station side when receiving control information on the remote I / O station side.
Whether the data received in step S11 is from the remote master station 15 is confirmed using the transmission source station number of the received transmission frame (see FIG. 2).
If it is from the remote master station 15, it is confirmed in step S12 whether the first control data is received from the remote master station 15, and if it is the first reception, the link scan time measurement timer is started in step S13. To do.
At this time, since each remote I / O station 25 is broadcast simultaneously by a global command, the link scan measuring circuit 52 built in each remote I / O station 25 in FIG. 4 is activated.
[0030]
The reason for confirming in step S12 that “the first control data is received from the remote master station?” Is that the startup order of the remote master station 15 and the remote I / O station 25 is taken into consideration.
As shown in FIG. 3, the link scan definition is a time interval between data transmission of the remote master station and data transmission of the next remote master station.
Therefore, each remote I / O station needs to recognize the data transmission of the first remote master station for each, and in step S12 it is determined whether or not “first control data reception from remote master station?” In step S13, the link scan measurement circuit 52 is activated.
[0031]
The control information reception interval from the master station is unique with the link scan time, and the clock information received from the master station has a transmission delay corresponding to the link scan time.
The measured value obtained by starting this timer is used for the clock information correction as the link scan time.
On the other hand, if it is determined in step S12 that it is not the first data reception from the remote master station, in step S14, the timer value is read from the link scan time measurement timer to obtain a correction value.
Next, in step S15, link scan time measurement is timer preset to prepare for the next correction.
[0032]
FIG. 7 is a flowchart showing processing at the time of receiving clock information on the remote I / O station side.
In step S21, whether or not clock information is received from the remote master station is determined from the transmission source station number and the command content in the transmission frame (see FIGS. 2 and 4).
The transmission I / F 53 of each remote I / O station has a built-in command decoder 53C to determine the type of transmission frame.
The transmission frame is clock information, the link scan time can be measured, and the correction of the clock information is completed by adding the link scan time to the clock information of the transmission frame.
[0033]
By these operations, the above-described processing is performed in all remote I / O stations, so that the clock of the entire system can be uniquely determined.
[0034]
According to the present invention, since the above-described processing is performed in all remote I / O stations, the clock information is transmitted using the same communication frame as the conventional one, so that the system is compatible with the conventional model while ensuring compatibility. The entire clock can be determined uniquely.
In the remote I / O network system, only one clock circuit is required, and the user does not need to adjust the clock at each station. Furthermore, the clock information of the remote master station is corrected to the clock information of the remote I / O station side at the link scan timing and preset. Therefore, if the clock information of the controller of the remote master station is accurately set, the system clock is automatically matched.
In addition, because the correction of the clock information transmission delay is performed at the link scan timing, no error corresponding to the transmission delay time occurs between the clock information transmitting station and the clock information receiving station regardless of the degree of the transmission delay. .
[0035]
In the above-described embodiment, the remote I / O system including the remote master station and the remote I / O station has been described. However, the remote master station serves as a master station, and other slave stations having a CPU unit. Similarly, even in a system configured with a local station, the clock information sent from the master station is received by the local station, corrected for the time of the link scan time, and has unique clock information throughout the system. be able to.
As for the matching of clock information between the master station and the local station, the clock information can be matched as a system without building an application by the user (without the user being aware of the time adjustment of the master station and the local station). Further, since correction of the sent clock information is also performed, time adjustment with excellent reliability and reliability can be performed, and a clock in the system can be uniquely determined.
[0036]
【The invention's effect】
In the present invention, when the system time is adjusted with the clock information of the controller adjacent to the master station in the control system, the remote I / O station of each station performs transmission / reception of clock information and correction of the transmission delay time. Time with excellent reliability and reliability, and a clock in the system can be uniquely determined.
In addition, time adjustment with excellent reliability and reliability can be performed between the master station and the local station, and a clock in the system can be uniquely determined.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a control system of a PC adopting a remote I / O network of the present invention.
FIG. 2 is a diagram showing a transmission frame used at the time of transmission / reception by the remote master station and the remote I / O station of the present invention.
FIG. 3 is a diagram showing timing for exchanging control information between a remote master station and a remote I / O station of the present invention.
FIG. 4 is a diagram showing a time adjustment method for a remote I / O network according to the present invention.
FIG. 5 is a flowchart showing clock information transmission processing of the remote master station of the present invention.
FIG. 6 is a flowchart showing a remote I / O station side control information reception process according to the present invention.
FIG. 7 is a flowchart showing clock information reception processing on the remote I / O station side of the present invention.
FIG. 8 is a standard control system configuration diagram of a PC adopting a conventional remote I / O network.
FIG. 9 is a diagram showing a transmission frame used at the time of transmission / reception between a conventional remote master station and a remote I / O station.
FIG. 10 is a diagram showing a timing for exchanging control information between a conventional remote master station and a remote I / O station.
[Explanation of symbols]
1 master system, 2 subsystem, 3 transmission cable, 4 termination resistor, 10 system bus, 11 controller, 15 remote master station, 20 system bus, 25 remote I / O station, 32 clock circuit, 42 clock storage area, 52 link Scan measurement circuit.

Claims (6)

Control system comprising a remote master station connected via a system bus to a controller that employs a refresh method, a remote I / O station which is controlled by the connected said remote master station through the network to the remote master station Contact Keru a time alignment method of network,
The remote master station, and transmitting the clock information received from the controller, with respect to the remote I / O station in synchronization with the END timing of the controller,
The remote I / O station, upon receiving the clock information, to correct the transmission delay of the link scan time content is corrected with respect to the unit are connected via a system bus and remote I / O station Providing the clock information,
Network time adjustment method including Remote I / O station measures a reception interval of the control information from the remote master station, by adding the measured values of the received clock data from the remote master station, you correct the transmission delay of the link scan time min The network time adjustment method according to claim 1, wherein: A master station connected via a system bus to a controller that employs a refresh method, a time synchronization method in our Keru network control system comprising a local station that is connected via a network to the master station,
Said master station, the clock information received from the controller, and transmitting to said local station in synchronism with the END timing of the controller,
Said local station, upon receiving the clock information, to correct the transmission delay of the link scan time component, the step of modifying the clock information of the local station itself,
Network time adjustment method including Local station measures a reception interval of the control information from the master station, by adding this measurement to clock information received from the master station, and features that you correct the transmission delay of the link scan time min The network time adjustment method according to claim 3 . A control system comprising a remote master station connected to a controller adopting a refresh method via a system bus, and a remote I / O station connected to the remote master station via a network and controlled by the remote master station Because
The remote master station transmits the clock information received from the controller to the remote I / O station in synchronization with the END timing of the controller,
When the remote I / O station receives the clock information, it corrects the transmission delay for the link scan time and corrects the unit connected to the remote I / O station via the system bus. Provide clock information,
A control system characterized by that. The remote I / O station measures the reception interval of the control information from the remote master station, and corrects the transmission delay for the link scan time by adding this measured value to the clock information received from the remote master station. The control system according to claim 5.

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