JPH02113746A - Signal synchronizing system - Google Patents

Abstract

PURPOSE:To facilitate the procedure of synchronizing control by correcting the length of an idle data frame sent from a master station prior to a main synchronizing data frame in the cyclic time of a predicted token based on network constitution station information and timing of new station invitation. CONSTITUTION:A bus network consists of stations 11-1n constituting the network, optical fiber cables 21-2n, and an optical star coupler connecting the stations 11-1n via the optical fibers 21-2n. Then a master station 11 sends an idle data frame whose length is set based on a time difference between a transmission end time of a main synchronizing data frame and a main synchronizing signal prior to the transmission of a main synchronizing data frame and the length of the idle data frame is corrected by the token cyclic time and the timing of new station invitation predicted based on the network constitution station information. Thus, the procedure of synchronizing control is facilitated.

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 (
The invention relates to a signal synchronization method for simultaneously sampling instantaneous values of voltage, current, etc., for example.

[Conventional technology]

Local area networks (hereinafter referred to as LA, N) have been rapidly becoming popular in recent years, and one notable trend is the manufacturing automation protocol (AP) proposed by General Motors of the United States. uto
There is a growing interest in industrial LANs called industrial LANs. FA, (factory automation F factory A
utoma=2 tjoguchi), OA (Office Automation Off)
A large number of devices such as robots and computers have been introduced into factories and offices for ice automation, and the standardization of the MAP is being promoted with the aim of interconnecting these devices easily and at low cost.

It aims to become an industry standard rather than a single company's LA, N, and many leading companies are participating. International Organization for Standardization (ISO) 08I (Open System Interconnection)
Standardization is progressing by filling in each layer of the hierarchical model (physical layer, data link layer), and the lower two layers (physical layer, data link layer), excluding the logical link control sublayer, are standardized by the American Council of Electrical and Electronics Engineers (The In5tit
Ute of Electricaland E 1e
ctronics engineers Inc.
The token passing bus of the IEEE 802.4 committee is used. Currently IEEE802゜4
Although the standard specifies that coaxial cable be used as the physical layer transmission medium, the application of optical fiber cable is also being considered, and even if the medium is optical fiber cable, the data link layer communication method is exactly the same. .

FIG. 5 is a block diagram showing a network in which this token passing bus is constructed using optical fibers. In the figure, 11 to 1n are stations configuring the network, and 21 to 2
n is an optical fiber cable, 3 is this optical fiber 2. ~2
This is an optical star coupler that connects the stations 1° to 1n with each other via the optical star coupler.

Next, the operation will be explained. A method in which each station arbitrarily transmits data to a bus network (C8M, A/CD)
However, as the amount of transmitted data increases and the load increases, the transmission efficiency decreases rapidly. 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, and each station remembers the station to which it should pass the token (successive = 3-stations), which allows the token to circulate through a logical ring ( (hereinafter referred to as a logical ring) is configured.

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.

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

(2) If the subsequent station fails, the subsequent station of the failed station will receive 1-
− Handle the node and remove the faulty station from the logical ring.

(3) New stations are invited at regular intervals, and stations that wish to join the logical ring are allowed to do so.

On the other hand, there are applications in which this token passing bus is used to control devices at high speed, and among these, there are systems in which it is necessary for each station to repeatedly generate a specific signal at the same time. For example, consider a system that requires synchronization of sampling signals to obtain instantaneous values of voltage, current, etc. at the same time at multiple points. In such a system, a method of signal synchronization using a token passing bus is to synchronize a particular station, for example, station 1. is the master station for signal synchronization, the other stations 12 to 1n are slave stations for signal synchronization, and the master station 1. The slave stations 12 to 1n use the data frames periodically transmitted by the master station 1. One possible method is to synchronize according to the

FIG. 6 is a time chart showing such a conventional signal synchronization method. is the period t of the main synchronizing signal S1. At the same time, the data frame D of the main station 11 is transmitted in synchronization with this main synchronization signal S1, and the data frame D of the main station 11 is transmitted to the slave stations 12 to 1n.
is used to determine the generation time of the main synchronization signal S1 by calculating backward from the arrival time of the data frame D, thereby making it possible to synchronize the signals of all stations participating in the network. Here, the data frame D for synchronization transmitted by the main station 11 is assumed to be a main synchronization data frame. Furthermore, a main synchronization data frame D is generated in synchronization with the main synchronization signal S1.

In order to transmit at a constant cycle, the main station 11 transmits an empty data frame Ds before transmitting the main synchronization pig frame D1, and also calculates the time difference between the transmission completion time of the main synchronization data frame I)1 and the main synchronization signal S1. The length of the empty data frame Ds is changed accordingly.

As a result, main station 1. It becomes possible to transmit the main synchronization data frame D1 synchronized with the main synchronization signal S.

On the other hand, 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 D and the station synchronization control signal, so that the station synchronization signal follows the main synchronization signal S. signal synchronization is performed.

[Problem to be solved by the invention]

Conventional signal synchronization systems are configured as described above, so when stations participating in the network send solicitation frames at regular intervals to solicit new stations in order to maintain and expand the network, conventional signal synchronization systems In the synchronization method, new station solicitation is performed independently every cycle, so the transmission completion time of the main synchronization data frame increases each time new station solicitation is executed, as shown in Figure 6 (a) and (c), for example. As a result, the data transmission time of the slave station fluctuates, and depending on the method of adjusting the empty data frame of the master station, there are problems such as temporary loss of signal synchronization.

This invention was made to solve the above-mentioned problems, and aims to provide a signal synchronization method that reduces fluctuations in the data transmission time of slave stations and facilitates the synchronization control procedure of the master station. shall be.

[Means to solve the problem]

In the signal synchronization method according to the present invention, the main station transmits, prior to the main synchronization data frame, an empty data frame whose length is set based on the time difference between the transmission completion time of the main synchronization data frame and the main synchronization signal. , the length of this empty data frame is predicted based on the network constituent station information, 1
--The slave station synchronizes its own station synchronization signal with the main synchronization signal by detecting the completion of reception of this main synchronization data frame.

[Effect]

=8- In the present invention, the main station regarding signal synchronization calculates the length based on the time difference between the transmission completion time of the main synchronization data frame and the main synchronization signal, prior to transmitting the main synchronization data frame to be transmitted for synchronization. setting and transmitting an empty data frame, at that time, the length of the empty data frame is corrected using the token circulation time predicted based on network constituent station information and the timing of new station invitation, and A slave station related to signal synchronization detects the completion of reception of the main synchronization data frame and synchronizes its own station synchronization signal with the main synchronization signal, thereby reducing fluctuations in timing of data transmission between each station.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a time chart showing a signal synchronization method according to an embodiment of the present invention.

A1 to An indicate the station addresses of stations 11 to 1n in FIG. 5, respectively, and the relationship 80〉A, 〉...An holds true.

Now, as in the conventional case, station 1.1 on the token passing bus of FIG. The signal synchronization regarding the main station,
Stations 12 to]n are assumed to be slave stations regarding signal synchronization. 2 is a configuration diagram of a main synchronization data frame for explaining a method for transmitting solicitation synchronization commands by the main station 11, FIG. 3 is a flowchart showing the operation of the master station, and FIG. 4 is a flowchart showing the operation of the slave station ~1
12 is a flowchart showing the operation of n.

Next, the operation will be explained. First, the explanation will begin with station 1, which is the main station regarding signal synchronization. We will discuss the operation of

The master station j-+ executes the operations shown in the flowchart shown in FIG. 3 every time it passes a token to the connected station. That is, it has a counter for solicitation synchronization control that is decremented by 1 each time the token is circulated, and in step ST1, the current count value CNT of the counter is checked, and if it is not O, the count value CNT is
1 is subtracted from the count value CNT, and when the count value is 0, the maximum set value CNTmax is substituted as the count value CNT. In step ST2, the time difference between the transmission completion time of the main synchronization signal S and the main synchronization data frame D is measured. In step ST3, assuming that the sum of lengths of frames other than the empty data frame Ds transmitted last time and the sum of silences are not changed, r of the previous empty data frame and the time difference t measured from before are determined. , calculate the length ts of the empty data frame that should originally be transmitted. Normally, the formula for calculating the length of this empty data frame is, for example, "S 'A = ts previous - t", but other times, t5 current = t8 go2 t1 or t5 current = 2tS previous tS @ kart □ current + 11 Blind officers etc. are possible, but since this is not a feature of this invention, ts current = f(
t, ).

Next, in step ST4, it is determined whether or not the counted value CNT of the counter matches the result of multiplying the address A, n of the lowest address station 1-n of the participating stations in the network by a predetermined constant 8. If so, step ST8
, if they do not match, the operation of step ST5 is performed. In step ST5, whether or not the result of multiplying the count value CNT of the counter by the predetermined constant a by the addresses A, ~A, , of stations other than the lowest address station 1n among participating stations in the network match. Determine, if any match, step ST7; if all match, step ST
Perform step 6.

In step ST6, it is determined that no new station will be invited to participate in the network, and the length of the empty data frame Ds to be transmitted this time is assumed to be the length of the empty data frame Ds to be transmitted this time. use. Step S
At T7, station 1 except the lowest address station in the network. ~
Forecasting In-1's new station invitation, assuming the length t3 of the empty data frame Ds to be transmitted this time, the length t8 of the empty data frame to be originally transmitted is now the invitation frame C1 to C.
Use the value obtained by subtracting the length of , -U and the length of one response window, t. In step ST8, screws 1 to
The length of the empty data frame Ds to be transmitted this time is 11. Currently, a value obtained by subtracting the length t of the invitation frame Cn and the length 2·t of the two response windows from the length ts of the empty data frame 11 to be originally transmitted is used.

When these steps ST6 to ST8 are completed, the operation moves to step ST9. In step ST9, the empty data frame Ds having the length distribution of the empty data frame to be transmitted this time thus determined is added to the transmission queue. In step 5TIO, the counter is referred to, and if the count value CNT is 0, step 5TII is performed, and if it is not 0, step 5T12 is performed. Step 5T11
Now, for example, a main synchronization data frame D1 with a solicitation synchronization command SS as shown in FIG. 2 is added to the transmission queue. In step 5T12, the main synchronization data frame D1 without the solicitation synchronization command SS is added to the transmission queue.

A method for collecting network constituent station information is, for example, by extracting the frame transmission source address every time a data frame is received and arranging them in an internal memory in the order of reception. Further, the maximum setting value CNT+max is the maximum setting value CNT+max of station 1. It is necessary to select a value larger than the predetermined constant a times the address A1. Further, the main station 11 performs not only the operations shown in the flowchart shown in FIG. 3, but also the operations shown in the flowchart shown in FIG. In that case, step 5T21 and step 2
Operation 2 is omitted. The operation shown in the flowchart of FIG. 4 will be explained with reference to the operation of the slave station below.

Next, the operation of the stations 12 to ]n, which are slave stations regarding signal synchronization, will be explained.

Follower 1. ~1n executes the operation of the flowchart shown in FIG. 4 every time the token is passed to the connecting station.

That is, in step ST2]-, the invitation synchronization command SS is sent every time the main synchronization data frame received from the main station J1 is received.
If there is, in step 5T22, substitute ○ for the count value CNT of the counter for solicitation synchronization control,
The operation in step 5T23 is executed. Solicitation synchronization command SS
If not, the operation of step 5T23 is executed as is.

In step 5T23, the counter is referred to and its count value C
If NT is not 0, j is subtracted from the count value CNT, and if it is 0, the maximum set value CNTmax is substituted for the count value CNT. At step 5T24, the count value CNT of the counter is
If the results of multiplying the own station's addresses A and ~An by the predetermined constant a match, a new station invitation is executed in step ST26, and if they do not match, solicitation is prohibited in step ST25. do.

Main station 1 as above. and slave station] The operations of 2 to 1n are illustrated in the time chart shown in FIG.

In other words, in the case of Figure 1 A), the count value CN of the counter
After the maximum setting value CNTmax is set in T, the count value CNT is subtracted by 1 every time the token goes around, and new station solicitation is not performed, and the empty data frame Ds to be transmitted this time is The transmission completion time of the main synchronization data frame D is synchronized with the main synchronization signal Si using the length of the original empty data frame t; s, ct5 = f(t+)) as the length representation.

In case b), main station 11 solicits a new station, and main station 1□
is the length t of the empty data frame Ds to be transmitted this time, the length t of the original empty data frame tS, the length of the solicitation frame C1, and the length t of one response window are subtracted from the current length tS, resulting in D8. 1s, -1-1w), the transmission completion time of the main synchronization data frame D1 and the main synchronization signal S,
are synchronized. In case A), the slave station 12 solicits a new station, and as in case A), the main synchronization data frame D,
The transmission completion time and the main synchronization signal S are synchronized.

In the case of [4], the lowest address station [n] invites a new station, and the empty data frame Ds to be transmitted this time is sent by the main station]-1.
Using t0 seaj:o-2・tW as the length representation, and also the transmission completion time of the main synchronization data frame D,
The main synchronization signal S is synchronized.

In case e), the count value CNT of the counter is the minimum station 1. is smaller than the predetermined constant a times the address An, no new station invitation is performed, and the length t of the empty data frame Ds that the main station 11 should send this time is the length t of the empty data frame that should originally be sent. Use Sashi S Gen. Therefore,
The transmission completion time of the main synchronization pig frame D1 and the main synchronization signal S.

are synchronized.

Length t of solicitation frames C1 to Cn. is IEEE802.
The length is defined in the four standards, and the length of the response window is set in advance as a system-specific value. Therefore, the length t of C1 to Cn of the solicitation frame and the length tW of the response window must be held as fixed values in the main station 11. In addition, the main station 11. Follower 1. ~1
Operations other than those shown in Figures 3 and 4 are also necessary for both cases, but 1
Since this is not a feature of the present invention, its explanation will be omitted.

In the second embodiment, as a synchronization method for soliciting new stations, the master station periodically transmits solicitation synchronization commands, and a counter for solicitation synchronization control is provided for each cycle, so that all participating stations in the network The master station periodically solicits new stations in synchronization with the master station regarding signal synchronization, but the master station transmits the count value of the counter each time, and the slave stations refer to the received count value of the counter every time. New station solicitation may be controlled using the same determination as described above, and the same effects as in the above embodiment can be achieved.

〔Effect of the invention〕

As described above, according to the present invention, the length of the empty data frame transmitted from the main station prior to the main synchronization pig frame is predicted based on the network constituent station information.
- Since it is configured to be corrected according to the rotation time of the master station and the timing of new station invitation, the transmission end time of the master station's main synchronization data frame can be kept constant in synchronization with the main signal, and therefore the slave station's transmission Since the timing is kept constant in synchronization with the main synchronization signal, stable signal synchronization can be obtained, and the synchronization control procedure becomes easier, reducing constraints on the software on the system operation side. There is.

[Brief explanation of drawings]

FIG. 1 is a time chart showing a signal synchronization method 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. FIG. 4 is a flowchart showing the operation of the slave station regarding signal synchronization in this embodiment. FIG. 5 is a configuration diagram of a bus network to which the present invention is applied. FIG. 6 is a flowchart showing the operation of the slave station regarding signal synchronization in this embodiment. It is a time chart showing the method. 1 is a main station, 12 to 1n are slave stations, 21 to 2n are optical fiber cables, and 3 is an optical star capsuleer. ~Tn is a token frame, Dl is a main synchronization data frame, S is a main synchronization signal, 1. is the time difference between the transmission completion time of the main synchronization data frame and the main synchronization signal, Ds
is an empty data frame, and SS is a solicitation synchronization command. In addition, in the figures, the same reference numerals indicate the same or equivalent parts. Agent Masuo Oiwa

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. , when transmitting the empty data frame, predict the circulation time of the token and the timing of new station invitation based on network constituent station information, modify the length of the empty data frame based on them, The signal synchronization method is characterized in that the station synchronization signal of the own station is synchronized with the main synchronization signal by detecting the completion of reception of the main synchronization data frame.