JPH063921B2 - Signal synchronization method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention utilizes a signal synchronization method, in particular, a token passing bus, and sampling for simultaneously obtaining instantaneous values of voltage, current, etc. at a plurality of points separated from each other. The present invention relates to a signal synchronization system for signals and the like.

[Conventional technology]

The local area network (LAN) has been rapidly spreading in recent years, and one of the notable trends among them is the MAP (Man) proposed by General Motors (GM) of the United States.
Industrial L called ufacturing Automation Protocol
There is a growing interest in AN. Many devices such as robots and computers have been introduced into factories and offices for FA and OA, but standardization of MAP is being promoted for the purpose of easily and inexpensively connecting these devices. It aims to be an industry standard rather than a LAN for one company, and many leading companies are participating. I
OS (International Systems Organization) OSI (Open Systems Interc
onnection) Standardization is underway by filling each layer of the hierarchical model. The lower two layers (physical layer, data link layer) except the theoretical link control sublayer are IEEE (US Electrical and Electronic Engineers Conference) 802.4. The Commission's token passing bus is used.

An example of the structure of this token passing bus is shown in FIG. The stations 1 ₁ to 1 _n forming the network are connected to the coaxial cable 2 via branching devices 3 _{1 to} 3 _n called taps.
Although there is a system (CSMA / CD) in which each station arbitrarily transmits data in the bus type network, it has a drawback that the transmission efficiency rapidly decreases when the amount of transmission data increases and the load increases. In contrast, the token passing bus avoids this drawback with a deterministic access scheme. That is, a transmission right called a token is sequentially transmitted between the stations that are subscribing to the token passing bus, and a plurality of stations are prevented 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,
In addition, each station stores the station (successor station) to which the station should pass the token, and this constitutes a logical ring (logical ring) in which the token circulates. However, if this logical ring is fixed, even if a new station wants to join, it cannot join, and if any of the joining stations fails, the logical ring will break and communication will stop. Therefore, the token passing bus has the following ring maintenance function.

(1) When the token is temporarily lost due to noise, the previous token holding station reissues the token.

(2) When the succeeding station fails, give the token to the succeeding station of that station and remove the failed station from the logical ring.

(3) New stations are solicited at almost constant intervals, and stations that wish to join the logical ring are allowed to join.

On the other hand, there is an application field in which a LAN including the token passing bus is used to perform high-speed control of equipment, and there is also a system in which each station needs to repeatedly generate a specific signal at the same time. For example, generation of sampling signals for simultaneously obtaining instantaneous values of voltage, current, displacement, acceleration, etc. at a plurality of points can be mentioned. Therefore, if such signal synchronization can be performed by using the token passing bus, which is one of the leading standards of LAN, the token passing bus has the excellent features of immediacy, self-healing property, and expandability that are originally provided. At the same time, the token passing bus can be used more widely.

As a method of performing signal synchronization using the token passing bus, a specific station is set as the master station, and a station other than the master station (slave station) is set to the master station by using a data frame periodically transmitted by the master station. A method of synchronizing can be considered. This will be described with reference to FIG. The master station to a station 1 _1. The synchronization signal (hereinafter abbreviated as the main synchronization signal) S ₁ generated by the main station is generated in the cycle T. If, if transmitted synchronously data frame D ₁ from the main station 1 ₁ to the main synchronization signals S _1, slave station 1 ₂ to 1 _n is the time of occurrence of the data frames D ₁ of the by calculating back from the reception time master synchronizing signals S ₁ You can know. This is because, in the talk passing bus, the data frame D ₁ is received by all slave stations at substantially the same time if its destination address is appropriately set.

To achieve signal synchronization mentioned above, there is a problem of how to transmit the data frames D ₁ in synchronization how to the main synchronization signals S ₁ at the main station 1 _1. Originally, in the token passing bus, the token circulates according to the algorithm for maintaining the logical ring, and the circulation period is not the same as the synchronization signal period T, of course, solicitation of a new station and the token passing retry are established phenomena. It must be considered that it always changes because it is carried out automatically. Therefore, to perform signal synchronization using a token-pathing bus, it is essential if possible occupy means that the main station 1 ₁ sends a data frame D ₁ in synchronization with the main synchronization signal S _1. As one of the methods, there may be considered a method in which the main station 1 ₁ waits until the time of the main synchronization signal S ₁ for the transmission of the data frame D ₁ to be transmitted immediately after receiving the token. However, now that the case no-signal state continues for a long time, and retransmits the token is regarded as the main station 1 prior station which transmitted the _token into the token-pathing fails, further a failure the master station 1 ₁ There is a problem of taking it out of the logical ring.

[Problems to be solved by the invention]

As described above, in the method in which the signal cycle is performed using the token passing bus by making the transmission of the data frame D ₁ wait until the time of the main synchronization signal, the token passing fails because the signalless state continues for a long time. However, there was a problem that the main station was regarded as a failure.

Therefore, an object of the present invention is to solve the above-mentioned problems and to provide a token passing function which is originally not provided with a signal synchronizing function with a signal synchronizing function without deteriorating the features originally provided, and to provide a token passing function. It is an object of the present invention to provide a signal synchronization method that can further broaden the usage of the bus.

[Means for Solving Problems] The gist of the present invention is to use an empty data frame for adjusting a transmission time of a data frame for signal synchronization (hereinafter, abbreviated as a synchronization data frame) in a signal synchronization main station, and By changing the length of the empty data frame according to the time when the main station receives the token, it is possible to transmit the synchronous data frame synchronized with the main synchronous signal.

That is, a plurality of slave stations are connected to a specific signal transmission path, and the slave station consisting of a master station and a slave station starts signal transmission of the slave station in response to reception of a token included in the transmission signal, and transmits the signal. At the end of, the token is transmitted to the next slave station to enable inter-slave station signal transmission in a predetermined order, and the input time of the process amount of the process provided in the slave station is set between multiple slave stations. Simultaneously and in a signal synchronization method for performing in a fixed cycle, the main station detects the main synchronization signal generated in a predetermined cycle, generates a synchronization data frame in response to the detection of the means, and transmits it. Means, a means for transmitting a token to a predetermined slave station after the completion of transmission of the synchronous data frame, a means for detecting the time when the token is received from another slave station, a predetermined time when the token is received from another slave station Long fixed length frame Means for transmitting a variable-length frame of variable time, and a transmission time length of the variable-length frame according to the time difference between the transmission completion time of the fixed-length frame and the time of next detecting the main synchronization signal. Means for variably adjusting, said slave station, means for starting transmission of its own signal when receiving a token from another slave station, means for transmitting a token to a predetermined slave station after completion of transmission of its own signal , A means for inputting the process amount of the process of the slave station after a predetermined time from the reception of the synchronous data frame, wherein the predetermined time of the slave station depends on a signal transmission delay time between the master station and the slave station. It is designed to achieve the intended purpose by synchronizing the input times of the process quantities at multiple slave stations.

[Action]

The empty data frame transmitted prior to the synchronization data frame is divided into a fixed length portion and a variable length portion, the fixed length portion is transmitted first, and the variable length portion is transmitted later. Immediately after recognizing the arrival of a token, transmission of the fixed length portion of the empty data frame is started first. Since the main station has a time margin while the fixed length portion is being transmitted, the length calculation of the variable length portion is performed based on the transmission start time of the fixed length portion detected by the means for knowing the transmission start time. Then, the variable length portion adjusted to have such a timing as to synchronize the synchronization data frame with the main synchronization signal is continuously transmitted after the transmission of the fixed length portion is completed. Therefore, the synchronization data frame that is transmitted subsequently to this variable length portion is transmitted in synchronization with the main synchronization signal.

The slave station receives the synchronization data frame thus synchronized with the main synchronization signal and synchronizes its own synchronization signal with the synchronization data frame.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 9.

The main station with respect to the station 1 ₁ signal synchronized in the token-pathing bus shown in Figure 2, the station 1 ₂ to 1 _n is the slave station.

a. Detailed description of the main station The main station ₁₁ has a signal source for the main synchronization signal S ₁ . FIG. 3 shows the state of the token passing bus in which signal synchronization is performed, and D ₁ , D ₂ , D ₃ , ... Are stations 1 ₁ , 1 ₂ , 1 ₃ , ...
, And T ₁ , T ₂ , T ₃ , ... Represent tokens, whereas D _S is an empty data frame transmitted by the master station 1 ₁ for time adjustment. FIG. 4 is an enlarged view of this portion, in which the master station 1 ₁ transmits an empty data frame D _S before transmitting the synchronous data frame D ₁ . Even in the steady state where the logical ring is completed and all subscriber stations have no failure, the transmission data length t _i (i = 1 to n) of each station
Can change. Moreover, since the token reissue if the token is temporarily extinguished by noise or the like, also for issuance solicitation frame if any station makes a new station invitation, token arrival time to the main station 1 ₁ Become slow. Therefore, as an empty data frame length t _S is the transmission time of the synchronization data frame D ₁ is synchronized with the main synchronization signal S _1, must be changed in accordance with the token arrival time to the main station 1 _1. Here, as a precondition, the sum total T _TRO of the sum of the inter-frame clearance time t _F , the sum of all station token transmission times t _T , and the sum of all station maximum data frame transmission times t _max is smaller than the synchronization signal period T. , And the difference T−T _TRO between them is the gap t _F between the frames and the minimum length t of the empty data frame D _S.
Must be greater than the sum of _smin . Here, the gap time t _F is the sum of the transmission delay between stations and the station delay time that occurs in signal processing of the stations.

However, in the token passing bus, the empty data frame length t _S cannot be changed as it is according to the token arrival time. First, the station generally does not have the function of knowing the time when the token arrives. Second
In addition, since the main station 1 ₁ starts transmitting the empty data frame D _S immediately after recognizing the arrival of the token, there is no time to calculate the empty data frame length t _S.

Thus, first with respect to the first problem, and to provide means for detecting an air data frame D _S transmission start time as shown in example Figure 5 with respect to the main station 1 _1. That is, the transmission start detection circuit 16 outputs the output signal T _X1 from the token passing bus control circuit (hereinafter abbreviated as TBC) 12 to the modem 11.
This is input and the transmission start detection circuit 16 generates a transmission start pulse Q _S. This pulse Q _S triggers the timer with register 17 to store the transmission start time and Q _S causes the token start pulse to be stored. The single-bus processor 13 is requested to interrupt and read the transmission start time. Further, the timer 17 with a register is triggered by the main synchronizing signal S of the synchronizing signal generating circuit 20 to store the time from the transmission start to the main synchronizing signal.

Then, for the second problem, a null data frame as shown in FIG. 1 (a) divided into a fixed-length frame D _SA and variable length frame D _SB, while sending the fixed length frame D _SA employ a method of calculating the frame length t _SB of variable length frame D _SB. That is, the processor 13 puts the fixed length frame D _SA in the transmission queue in advance. When the transmission of the fixed length frame D _SA is started, the processor 13 performs the transmission start time (or the time t _P from the transmission start to the main synchronization signal) by the above-mentioned means.
The calculated, thereby calculating the length t _SB of the variable length frame D _SB, added to the transmission queue continues to variable length frame D _SB of its length t _SB in the fixed-length portion D _SA. The length t _SA of the fixed length portion is selected to be longer than this calculation / processing time.

The above explanation is t _P > t _SA + t _F (t _F : frame interval)
This is the case (Fig. 1 (a)). When t _P <t _SA + t _F as shown in FIG. 1 (b), the variable length portion _DSB is not transmitted because the time is exceeded.

The frame format of the data frames D ₁ to D _n and null data frames D _SA, D _SB are shown in Figure 6.

By the above means, the main station 1 ₁ synchronizes with the main synchronization signal S ₁ in synchronization with the synchronization data frame D 1 except in the case where the arrival of the token is abnormally delayed for some reason, as shown in FIG. 1 (b). It becomes possible to start sending ₁ .

b. DETAILED DESCRIPTION In contrast to the slave station, in the conventional 1 ₂ to 1 _n synchronous data frame D ₁
Since the signal indicating the completion of reception is output from the TBC 12 in FIG. 5, the synchronization signal S (S _{2 to} S _n ) can be synchronized with the start of reception of the synchronization data frame D ₁ by using this.

That is, in the configuration example of FIG.
C12 receives the interrupt request IRQ is notified of a data frame D ₁ received complete than when generating a received synchronization pulse Q _R from the output port 21 immediately. The phase comparator 22 uses the synchronization signal S
And the reception synchronization pulse Q _R are compared in phase, and the synchronization signal generator 20 uses the phase comparison result DPH so that the synchronization signal S coincides with a time t ₀ earlier than the reception synchronization pulse Q _R. Adjust the phase. Here, t ₀ is equal to the length t ₁ of the synchronous data frame D ₁ if the inter-station transmission delay, the station delay is ignored, but if these delays are corrected, the synchronization becomes more accurate.

Note that FIG. 5 shows an example of the configuration in which both functions of the master station and the slave station are provided. When the master station is the master station, the phase comparison result DPH is not used to explain the phase of the synchronization signal S, and when the master station is the slave station, the transmission is performed. The start pulse Q _S is ignored.

Incidentally, the error between the transmission time and the main synchronization signals S ₁ synchronous data frame D ₁ of the from the main station 1 ₁ As described above, the token ring overlaps temporary loss and new stations solicitation token to the main station 1 ₁ If it is abnormally delayed, it may become significantly large (Fig. 1 (b)). If this frame is used as it is on the slave station side, the error of the slave station side synchronization signal S (S _{2 to} S _n ) is naturally increased. In order to prevent this, as shown in FIG. 7, 2δt with reference to the slave side synchronization signal S.
Provided tolerance, but may come within the scope as (a), may be taken a method to ignore this case the received synchronization pulse Q _R exceeds this range as shown in (b).

c. Detailed Description of Addresses of Empty Data Frame and Synchronous Data Frame The destination address of the empty data frame D _S may be an individual address of a specific slave station or a group address indicating all slave stations. This is intended to carry some useful information in the "empty" data frame D _S.
However, since the slave station receives a large amount of "empty" data frame D _S , not only the unnecessary buffer memory is required, but also the receiving process of the data is required. There arises a problem that it temporally overlaps with the reception and signal synchronization processing of the synchronous data frame D ₁ received immediately after _S. Therefore, such addressing should be avoided unless there are special reasons.

As a destination address of the empty data frame D _S , it is appropriate to use a fictitious address that does not actually exist on the token passing bus or a station address that is not directly related to signal synchronization. In this way, this empty data frame D _S becomes a frame that can be ignored by the slave station.
The processing can be started immediately after receiving the synchronous data frame D ₁ . Further, a station not related to signal synchronization does not need to process the synchronous data frame D ₁ like a synchronous slave station, and the data contained in the “empty” data frame D _S can be used.

It said synchronization data frame D ₁ should be received in all synchronous slave stations 1 ₂ to 1 _n. The most reliable way to do (to "1" to all bits) broadcast address the destination address is to a group address including all synchronous slave stations 1 ₂ to 1 _n. In a system master station 1 ₁ failure when a single slave station 1 ₂ to 1 _n in to intercept the main station, the group address is intended to include all 1 ₁ and the synchronization master station the slave station 1 ₂ to 1 _n. This is because if there is a substitute, the fixed distinction between the master station and the slave stations cannot be made. In this case, the station 1 _{i, which} is currently the main station, receives the synchronization data frame D transmitted by itself.
By receiving _i (i = 1, 2, ... Or n), this is ignored.

d. Detailed Description of the synchronous data frame length The length t ₁ of the synchronous data frame D ₁ may have both cases of the variable and fixed. This relates to the synchronization processing method in the synchronization slave stations 1 ₂ to 1 _n . That is, in FIG. 5, TBC1
When the synchronization is performed by using the reception completion detection of the synchronous data frame D ₁ which utilizes the interrupt IRQ due to the completion of the reception of the data frame 2 of 2, the synchronous data frame length t ₁ is fixed in order to know the reception start time. And known to the sync slaves 1 ₂ to 1 _n .

If the synchronization data frame length t ₁ is variable, the means for detecting the start of reception of the synchronization data frame D ₁ in synchronization slave station 1 ₂ to 1 _n is required.

e. Detection method of transmission start in the master station, as a method of detecting transmission start in Description master station 1 ₁ and the detection method of the data frame reception in slave station, start delimiter S in the transmission frame shown in FIG. 6
There are a method of detecting D and a method of detecting the preamble PR. The pattern of the preamble PR and the start delimiter SD is shown in FIG. Here, FC is frame control, DA is destination address, SA is source address, FC
S is a frame check sequence and ED is an end delimiter.

Synchronous data frame D ₁ in the subordinate stations 1 ₂ to 1 _n
As a method of detecting the reception completion, it is certain that the TBC 12 issues an interrupt request IRQ to the processor 13 and determines that the processor 13 has received the synchronous data frame D ₁ . However, in the case where the anxiety of the interrupt processing time becomes a problem, for example, the received signal R in FIG.
_{Using X1} , detect the start delimiter SD (Fig. 6),
A method of using this together with the data frame D ₁ reception judgment by the processor 13 is required.

In FIG. 5, the output signal S of the synchronizing signal generating circuit 20 can be actually divided into a signal to the outside, a signal to the timer 17, and a signal to the phase comparator 22, and the timings of these signals are different. However, since they are generated from the same signal source, are synchronized with each other, and the timing difference is fixed, they are collectively treated as the synchronization signal S (or S ₁ ) in the above embodiment. .

[Other Examples]

In the above, the transmission line is not limited to the coaxial cable as shown in FIG. 2, but optical fiber cables 5 _{1 to} 5 _n and the optical star coupler 4 may be used as shown in FIG. 9, for example. Each of the optical fiber cables 5 _{1 to} 5 _n includes two optical fiber core wires, and for example, a transmission signal from the station 1 ₁ reaches the optical star coupler 4 via the transmission fiber of the optical fiber cable 5 ₁ , where After receiving the branch, the same signal passes through the receiving fibers of the optical fiber cables 5 _{1 to} 5 _n and the stations 1 ₁ to
Reach 1 _n . Although the topology is physically star-shaped, it can be logically treated as a bus-type. Note that C
Although it is a SMA / CD system and not a document of optical token bus, as a document of a network using a star coupler, it is No. 1780 (1984) of the University of Science and Technology, and No. 1 of the University of Science and Communication.
177 (1984).

Instead of detecting the transmission start using the transmission signal T _X1 in the main station as shown in FIG. 5, a method of detecting the arrival of the token using the reception signal R _X1 may be considered, and this is faster than the empty data frame variable. The calculation of the partial length t _SB will be started. However, even if a token arrives, the transmission of the null data D _S is not always started due to an error or the like contained therein, and it is necessary to determine whether or not the token is addressed to the own station. After all, this method is not realistic.

Further, although the IEEE 802.4 token passing bus is described in the above embodiment, the present invention can be applied to a network having a communication protocol similar to this.

〔The invention's effect〕

In short, according to the present invention, the following excellent effects are exhibited.

(1) An IEEE 802.4 token passing bus or a network having a similar communication protocol does not originally have a signal synchronization function, but an empty data frame is used in the signal synchronization master station, and the master station uses a token. By changing the length of the empty data frame according to the received time, it is possible to transmit the synchronous data frame in synchronization with the main synchronous signal, so that the signal that is originally provided is not lost. Since it can be provided with a synchronization function, its application can be further expanded in combination with the excellent immediacy, self-healing property, expandability, and flexibility inherent in the token passing bus or network.

(2) Therefore, by using a LAN including such token passing bus and network, high-speed control of devices that require synchronization, for example, instantaneous values of voltage, current, etc. are simultaneously obtained at multiple points separated from each other. Therefore, it is possible to effectively control the generation of a sampling signal.

[Brief description of drawings]

FIG. 1 is a block diagram showing an example of a method of transmitting an empty data frame in the signal synchronization system of the present invention, FIG. 2 is a block diagram of an example of a bus type network using a coaxial cable, and FIG. 3 is a token pad for signal synchronization. FIG. 4 is a block diagram of a transmission signal example of a single bus, FIG. 4 is an enlarged view of a master station transmission signal portion in FIG. 3, and FIG. 5 is a circuit of a station having both master station and slave station functions in the signal synchronization system of the present invention. block diagram illustrating a configuration example, the method Figure 6 ignores the IEEE 802.4 diagram illustrating a data frame format example of token-pathing bus, FIG. 7 is the slave station receives the sync pulse Q _R in the signal synchronization method of the present invention embodiment Figure 8 shows the timing chart, and Figure 8 shows the IEEE 80
2.4 Pattern configuration diagram of preamble PR and start delimiter SD in the token passing bus, and FIG. 9 is a configuration diagram showing an example of a network of another embodiment using an optical fiber and an optical star coupler. In the figure, D ₁ ... Synchronous data frame, D _SA ... Fixed length frame, D
_SB ... variable length frame, T ₁ through T _n ... token, S ₁ ... main synchronization signal, the time difference between t _P ... transmission start time and the main synchronization signal having a fixed length frame, 1 ₁ to 1 _n ... Token pathing bus stations 2 ... coaxial cable, 3 ₁ to 3 _n ... tap (splitter),
4 ... optical star coupler, 5 ₁ to 5 _n ... optical fiber cable (2-core fiber), 11 ... modem (the modem circuit), 12
... Token passing bus control circuit (TBC), 13 ... Token passing bus processor, 14 ... Memory, 15
... Interface with upper position, 10 ... Transmission start detection circuit, 17 ... Registered timer, 20 ... Sync signal generation circuit, 21 ... Reception sync pulse output port, 22 ... Phase comparator.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (71) Applicant 999999999 Toshiba Corporation 72 Horikawa-cho, Sachi-ku, Kawasaki-shi, Kanagawa (72) Inventor Kunio Matsuzawa 1-3-3 Uchiyuki-cho, Chiyoda-ku, Tokyo Within Tokyo Electric Power Co., Inc. (72) Inventor Kazuyoshi Yoshida 1-3-3 Uchisaiwai-cho, Chiyoda-ku, Tokyo Within Tokyo Electric Power Co., Inc. (72) Takafumi Maeda 1-3-1 Uchisai-cho, Chiyoda-ku, Tokyo Within Tokyo Electric Power Co., Ltd. ( 72) Inventor Kazuo Sano 1-1-1 Kokubuncho, Hitachi City, Ibaraki Prefecture Inside the Kokubun Factory, Hitachi, Ltd. (72) Fumiki Sone 5-1-1 Hidakacho, Hitachi City, Ibaraki Hitachi Cable, Ltd. Inside the Electric Wire Laboratory (72) Inventor Kazuhiko Takeda 5-1-1 Hidaka-cho, Hitachi City, Ibaraki Hitachi Cable Electric Wire Co., Ltd. (72) Inventor Takashi Yoshida Compartment Kobe-shi, Hyogo-ku, Wadasaki-cho 1-1-2 Mitsubishi Electric Corporation control in the Works (72) inventor Shiobara KanHisashi Fuchu, Tokyo Toshiba-cho, address 1 Toshiba Fuchu in the factory

Claims (1)

[Claims] 1. A plurality of slave stations are connected to a specific signal transmission line,
The slave station consisting of the master station and the slave station starts the signal transmission of the slave station in response to the reception of the token included in the transmission signal, and at the end of the signal transmission, transmits the token to the next slave station and transmits in a predetermined order. In the signal synchronization method for performing the signal transmission between the slave stations at the same time between the plurality of slave stations at the time of inputting the process amount of the process provided in the slave station, and The main station of the means for detecting a main synchronization signal generated in a predetermined cycle, means for generating and transmitting a synchronization data frame in response to the detection of the means, to a predetermined slave station after the completion of transmission of the synchronization data frame To send a token, a means to detect the time when the token is received from another slave station, a fixed length frame with a predetermined time length when a token is received from another slave station, and then a variable length variable time Send frame Means for variably adjusting the transmission time length of the variable length frame according to the time difference between the transmission completion time of the fixed length frame and the time at which the main synchronization signal is detected next, and the slave station is Means for starting transmission of its own signal when a token is received from the slave station, means for transmitting a token to a predetermined slave station after completion of transmission of its own signal, the slave after a predetermined time has elapsed from the reception of the synchronous data frame. The station has a means for inputting the process amount of the process, the predetermined time of the slave station is individually determined according to the signal transmission delay time between the master station and the slave station, the process amount of a plurality of slave stations. A signal synchronization method characterized by synchronizing input times.