JPH02135834A - Signal synchronizing system - Google Patents

Abstract

PURPOSE:To attain timewise efficiency at initializing of network by applying switching control of three transit states of asynchronous new station invitation state for a short period at initializing, invitation inhibit state for synchronizing looking and synchronizing new station invitation state for a prescribed period after signal synchronization establishment. CONSTITUTION:In the initial state when a network is built up, the interval of invitation specified by the IEEE 802.4 recommendations is minimized to quicken the time till the system operation is available and when the system operation is enabled, the invitation of new station is inhibited and the signal synchronization between a master station and a slave station is established quickly and efficiently. After the establishment of signal synchronization, the invitation of new station for network expansion is executed sequentially in an individual timing by each participant station periodically without losing the synchronization establishing state. Thus, the timewise efficiency at the initialize of the network is attained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a data transmission method, and in particular, the present invention relates to a data transmission method, and in particular, the present invention relates to a data transmission system that uses a token passing bus to transmit data (
For example, the invention relates to a signal synchronization method for simultaneously sampling instantaneous values of voltage, current, etc.

[Conventional technology]

Local area networks (hereinafter referred to as LANs) have been rapidly spreading in recent years, and one notable trend is the MAP proposed by General Motors of the United States.
(Manufacturing Automation Protocol)
There is a growing interest in industrial LANs called LANs. FA (Factory Automation)

A large number of devices such as robots and computers have been introduced into factories and offices for OA (Office Automation), and the purpose of this technology is to interconnect these devices easily and inexpensively. As such, standardization of the MAP is progressing. It aims to become an industry standard rather than a single company's LAN, and many leading companies are participating. International Organization for Standardization (ISO) 08I (Open System Interconnection)
onectLon) is being standardized by filling each layer of the hierarchical model, and the lower two layers (physical layer, data link layer) excluding the logical link control sublayer are
The Institute of Electrical and Electronics Engineers of the United States
te of Electrical and Elec
tronics Engineers Inc.
A token passing bus of the 802.4 committee (referred to as EEE) is used. Currently, the IEEE802.4 standard uses coaxial cable as the physical layer transmission medium, but the application of optical fiber cable is also being considered, and the token passing bus is FIG. 1 is a configuration diagram showing a network configured with fibers. In the figure, 1. -1n are stations forming the network, 21-2n are optical fiber cables, and 3 is this optical fiber cable 2. This is an optical star coupler that connects the stations 11 to 1n with each other through 2n.

Next, the operation will be explained. Although there is a method (C5MA/CD) in which each station arbitrarily transmits data in the bus network, it has the disadvantage that the transmission efficiency rapidly decreases as the amount of transmitted data increases and the load increases. Token passing buses, on the other hand, avoid this drawback through a deterministic access scheme. That is, a transmission right called a token is passed in order among the stations participating in the token passing bus, thereby preventing a plurality of stations from transmitting at the same time. Tokens are passed in order from the station with the largest address to the station with the smallest address.

Each station also remembers the station (subsequent station) to which it should pass the token, and this constitutes a logical ring (hereinafter referred to as "logical ring") around which the token circulates.

However, if this logical ring is fixed, if a new station wants to join, it will not be able to join, and if any of the joining stations breaks down, the logical ring will break and communication will stop. Therefore, the token passing bus has the following ring maintenance function.

(1) When a token is temporarily lost due to noise, etc., the previous token holding station will reissue the token.

do.

(3) Invite new stations at regular intervals and allow stations that wish to join the logical ring.6 On the other hand, there is an application field in which high-speed control of a single device is performed using this token passing bus. Among these, there are systems in which it is necessary to repeatedly generate a specific signal at the same time at each station.For example, there is a system in which sampling signals need to be synchronized to obtain instantaneous values of voltage, current, etc. at the same time at multiple points. think of. In such a system, a method for performing signal synchronization using a token passing bus is to make a specific station, for example, station 1□, the master station for signal synchronization, and other stations 1
□ ~ 1n are slave stations related to signal synchronization, and slave stations 12 ~ 1n are transmitted using data frames periodically transmitted by the main station 11.
One possible method is to synchronize with the main station 11.

FIG. 5 is a time chart showing such a conventional signal synchronization method, in which the main station 11 generates the main synchronization signal S1 with a period T, and synchronizes with this main synchronization signal S1 to generate the data frame of the main station 11. The slave stations 1□ to 1n calculate back from the arrival time of the data frame D to know the generation time of the main synchronization signal S, which enables signal synchronization of all stations participating in the network. shall be. Here, the data frame processing for synchronization transmitted by the main station 1□ is assumed to be a main synchronization data frame. Furthermore, in order to transmit the main synchronization data frame D1 at a constant cycle in synchronization with the main synchronization signal S1, the main station 1□ transmits an empty data frame Ds before transmitting the main synchronization data frame D0, and D1 transmission completion time and main synchronization signal S
The length of the empty data frame Ds is changed according to the time difference of 1. This enables the main station 11 to transmit the main synchronization data frame D1 synchronized with the main synchronization signal S1. −
The slave station controls the phase of the station synchronization control signal within its own station based on the time difference between the reception completion time of the main synchronization data frame D1 and the station synchronization control signal, so that the station synchronization control signal follows the main synchronization signal S1. Signal synchronization is performed.

[Problem to be solved by the invention]

Conventional signal synchronization systems are configured as described above, so when participating stations in the network transmit solicitation frames to solicit new stations in order to maintain and expand the network, the interval between new station solicitations is set at the time of initialization. If you set it for a long time, the time required to build the network will increase, which will delay the start of system operation.

When a new station invitation is performed when the main station related to signal synchronization performs synchronization pull-in to transmit the main synchronization data frame in synchronization with the main synchronization signal, the length of the empty data frame calculated from the measured time hand.

There is a difference in the length of the sum of the solicitation frame and the response window, and the control method becomes complicated to compensate for this difference.Furthermore, after the synchronization of the master station and the slave station is completed, it is necessary to maintain the synchronization established state stably. Therefore, not only is it necessary to conduct new station solicitation at relatively long intervals, but also because each station's new station solicitation is executed asynchronously, the transmission completion time of the main synchronization data frame every time new station solicitation is executed is the same as the main synchronization data frame. The signal fluctuates greatly, and the transmission timing of the slave station fluctuates significantly to follow it, making it necessary to consider the time margin for transmission preparation, making the signal synchronization control procedure complicated, and causing software constraints. There were problems such as the occurrence of

This invention was made in order to solve the above-mentioned problems, and provides a signal synchronization method that can improve time efficiency during network initialization and reduce the burden on software related to signal synchronization pull-in control. With the goal.

[Means to solve the problem]

In the signal synchronization method according to the present invention, a master station regarding signal synchronization sends its own station and slave stations into a short-cycle asynchronous new station solicitation state at the time of initialization, and a solicitation prohibited state for synchronization pull-in of the master station and slave stations. , and a synchronous new station invitation state at a constant period after signal synchronization is established, and these transition states are switched and controlled.

[Operation] According to the above, in the initial state when the network is constructed,
Minimize the solicitation interval stipulated in the IEEE802.4 standard to speed up the time until system operation is possible, and prohibit solicitation of new stations once system operation is possible.
Establish signal synchronization between the master station and slave stations quickly and efficiently, and after establishing signal synchronization, invite new stations for further network expansion, and periodically and each participating station Execute them sequentially at individual timings.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a state transition diagram of a master station and a slave station showing a signal synchronization method according to an embodiment of the present invention. In the figure, Ia and !
b is the first transition state, transition state! A is the initial state of the master station where new station invitations occur frequently, and transition state 1b is the initial state of the slave station where new station invitations are made frequently. In addition, Ha and nb are the second transition states, transition state a is a state dedicated to synchronization pull-in in the master station where new station solicitation is prohibited, and transition state nb is a state dedicated to synchronization pull-in in the slave station where new station solicitation is prohibited. It is. Furthermore, ■a and mb are the third transition states, transition state ma is a steady synchronization established state in the main station that synchronizes and invites new stations at regular intervals for network expansion, and transition state mb is also constant. This is a state in which steady synchronization is established in a slave station that periodically invites new stations for synchronization.

Here, as in the conventional case, in the token passing bus shown in FIG. 4, the two stations 11 are assumed to be master stations for signal synchronization, and the stations 12 to 1n are assumed to be slave stations for signal synchronization. Also,
FIG. 2 is a configuration diagram of a main synchronization data frame for explaining the method of transmitting the status of the main station 1□ and the slave stations 12 to 1n, and FIG. and a flowchart showing the operations of slave stations 1□ to 1n.

Next, the operation will be explained. The explanation will first describe the individual operations of each transition state.

A > ys Transition state 1a In transition state 1a, the main station 11 is in an initialization state in which it is determined that the system is not operable, and the main station 1□ receives the state status C8 on the main synchronization data frame D1 shown in FIG. to notify slave stations 1□ to 1n that the network is in the initial state, and also to set the solicitation interval (max-Inter-S o
(Licit-Count) to the minimum, and endeavors to build a network by inviting new stations at short intervals.

b) Operation of transition state 1b In transition state 1b, the slave stations 12 to 1n receive the state status C in the main synchronization data frame D1 received from the master station ], l.
A state that transitions when it is determined that 8 is the initial state,
Subordinate 1. Similarly to the main station 1□, ~1n attempts to establish a network by setting the solicitation interval to the minimum and soliciting new stations at short intervals.

1) Operation of transition state 11a In transition state 11a, signal synchronization has not been established, and the main station 1
1 prohibits its own station from soliciting for synchronization pull-in, transmits the status status C8 on the main synchronization data frame D1, and also instructs slave stations 12 to ]n to prohibit solicitation.

(English) Operation of transition state nb In transition state nb, slave stations 12 to ]n check the state status C on the main synchronization data frame D1 received from the main station 1°.
8, performs control to prohibit solicitation of its own station.

E) Operation of transition state ma In transition state ma, the signal synchronization of the network is established, and the main station 1. However, after prohibiting solicitation and performing signal synchronization pull-in in state 11a, when it is determined that signal synchronization of the network has been established, it transitions to the 1-line state. The master station 1□ restarts the invitation of new stations from the master station 1□ and the slave stations 1゜~1n, so it changes the state status C8 on the main synchronization data frame D1.
At the same time, an invitation synchronization command SS is periodically transmitted to the slave stations 1□ to 1n on the main synchronization data frame D1 at appropriate intervals so as not to affect signal synchronization.

Operation of transition state mb In transition state mb, slave stations 1□ to 1n receive the solicitation synchronization command SS based on the state status C8 from the master station 11.
Once in synchronization with , and so that the timing of new station invitations does not overlap between subordinate stations 1□ to 10.

After the invitation synchronization command is detected, a new station is invited after a fixed time period for each subordinate station 1□ to 1n.

Therefore, the operations in the main station 11 and the slave stations 1□ to 1n follow the flow shown in the flowchart of FIG. In step STI, it is determined whether the local station becomes a master station or a slave station regarding signal synchronization. usually.

In order to keep the network as long as possible, it is appropriate to designate the station with the highest address among the network participating stations as the master station.If the station becomes the 0th-order master station, step ST2 is performed, and if it becomes the slave station, step ST3 is performed. In step ST2, the main station compares the network configuration state with the preset minimum configuration station conditions for starting system operation, and determines whether the system can be operated. As a result, if the system is operational, step ST4. If it is not possible, the operation of step ST8 is performed. In step ST3, as a slave station, the status status C8 in the main synchronization data frame D1 from the main station 1□ is referred to.

If the main station is in the transition state Ha, perform the operation in step ST9, and if not in the transition state ma, perform the operation in step ST5. In step ST4, the main station determines whether network signal synchronization has been established from the state status of each station, If signal synchronization has been established, step ST6 is performed; if not, step ST7 is performed; in step ST5, the station operates as a slave station.

Referring to the state status C8 from the main station, if the main station is in the transition state 11a, step 5T10. Transition state 11
If it is not a, the operation of step STI 1 is performed.

In step ST6, the operation of the transition state ma described in e) above is performed. In step ST7, the operation of the transition state Ua described in the above item 3) is performed.In step ST8, the operation of the transition state 1a described in the above item 1) is performed.Step ST9
Then, in step 5TIO, the operation of the transition state mb described in the above step) is performed, and the operation of the transition state nb described in the above step) is performed. In step 5TII, the operation in the transition state 1b described in (a) above is performed.

In the above embodiment, the determination condition in step ST2 in FIG. 3 is whether the current network constituent station information satisfies the preset minimum configuration condition for starting system operation. Depending on the system to be applied, it may be determined whether a certain period of time has elapsed after the ring was formed, or whether a certain period of time has elapsed since a new station stopped joining, and the same effect as in the above embodiment can be achieved.

〔Effect of the invention〕

As described above, according to the present invention, there are three states: a short-cycle asynchronous new station solicitation state at the time of initialization, a solicitation prohibited state for synchronization pull-in, and a synchronous new station solicitation state of a fixed period after signal synchronization is established. Since the configuration is configured to switch and control the transition state, the interval between new station invitations is minimized during initialization, reducing the time required for network construction and increasing the efficiency of initialization, and synchronizing the master and slave stations. At the time of pull-in, new station solicitation is prohibited, simplifying the signal synchronization control procedure and shortening the synchronization pull-in time.Furthermore, after signal synchronization is established, new station solicitation is performed in synchronization with the main station. This has the effect of stabilizing synchronization.

[Brief explanation of the drawing]

Fig. 1 is a state transition diagram of each station showing a signal synchronization system according to an embodiment of the present invention, Fig. 2 is a configuration diagram of a main synchronization data frame transmitted in this embodiment, and Fig. 3 is an operation of this embodiment. Flowchart showing. FIG. 4 is a configuration diagram of a bus type network to which the present invention is applied, and FIG. 5 is a time chart showing a conventional signal synchronization system. 1 is the main station, 1□ to 1n are slave stations, 21 to 2n are optical fiber cables, 3 is an optical star coupler, T1 to Tn are token frames, Dl is the main synchronization data frame, Sl is the main synchronization signal, and Ds is the blank. Data frame, Ia and Ib are first transition states, Ila and Ilb are second transition states, ■a,
Inb is the third transition state. SS is the solicitation synchronization command, and CS is the state status. In addition, in the figures, the same reference numerals indicate the same or equivalent parts. Figure 3

Claims (1)

[Claims] A token passing bus, in which a plurality of stations form a logical ring, circulate tokens around the logical ring, and grant the right to transmit data only to the station that holds the token, or a similar device. In a signal synchronization method for synchronizing the transmission timing of data transmitted by each station in a network having a communication protocol, one of the plurality of stations is a master station for signal synchronization, the others are slave stations for signal synchronization, and the Prior to transmitting a main synchronization data frame for synchronization, the main station transmits an empty data frame whose length is determined based on the time difference between the transmission completion time of the main synchronization data frame and the main synchronization signal. , a first transition state in which each station invites new stations in a short period by minimizing the interval between new station invitations during network initialization when transmitting the empty data frame; and synchronized pull-in of the master station and slave stations. The second ban on soliciting new stations for
and a third transition state in which all participating stations in the network synchronize and sequentially solicit new stations based on the solicitation synchronization command from the main station after signal synchronization is established. A signal synchronization method characterized by controlling state switching.