JPH0523093B2 - - Google Patents

Description

Detailed Description of the Invention (Technical Field) The present invention relates to a synchronization device in a communication network system, and in particular to a method for transmitting two types of communication data, fixed format protocol data and arbitrary format transfer data, over the same transmission path. The present invention relates to a synchronization device for a communication network system.

(Prior Art) In recent years, with the development of office automation, development of short-range communication networks called local area networks (hereinafter referred to as LANs), which are suitable as data communication networks between various office machines, has become active. ing. However, such conventional general
In a LAN, the data transfer speed and data format on the network transmission path are fixed, so if a terminal device that is not compatible with these is connected to the network, a matching means such as a data buffer must be installed to Since it requires a means to match the transmission speed of the communication data or to convert the format of the communication data, it has the disadvantage of complicating the configuration and increasing the cost.

Therefore, in order to eliminate the above-mentioned drawbacks, we have made it possible to transmit communication data in any data format at any transmission speed from each terminal device, thereby eliminating the need for hardware for transmission speed matching or data format conversion. The communication network system developed by the applicant is disclosed in Japanese Patent Application No.
No. 59-33952). In other words, in this patented invention, the data transferred on the network is protocol data in a fixed data format at the basic speed at which the protocol operates, and data in an arbitrary speed depending on the performance of the terminal side and for which the data format is not specified. Two types of data are specified: special data for transfer and special data for transfer. When sending that special data on the transmission path, it must be specified in advance that all nodes in the network (terminals This control is carried out by notifying the communication control device) of this fact.

This prior invention refers only to the processing in the so-called steady state of the network in which both the terminal equipment side and the network can communicate and control by protocol is effective. However, in a network system, the so-called synchronization process from starting up a terminal to synchronizing the communication sequence operating on the network and bringing it to the above-mentioned steady state is called the steady state. There are other needs for time processing, and it is usually necessary to provide means other than the network control protocol for this purpose.

By the way, in conventional general networks, the data format and transmission speed of transmission data are uniformly predetermined in the same way as the above-mentioned protocol data, for example, as shown in Figure 1.
Like HDLC (High Level Data Link) format data format, special flag codes (or synchronization (SYNC) signals, etc.) indicating the start and end of valid data are placed in the flag areas before and after the data.
An identifier is provided. In conventional general networks, a dedicated discriminator circuit is used to discriminate between these identifiers at a certain frequency, thereby detecting a break in transmitted data, and making it possible to receive or transmit transmitted data from this point onwards. Synchronization to the communication sequence is being performed.

However, this conventional synchronization method simply cannot be applied to a network system in which data of arbitrary speeds and arbitrary formats coexist, as in the first invention described above. This is because the data in any format at any speed may contain the same code or signal as the identifier, or a signal that is likely to be misrecognized by the discrimination circuit.

(Objective) Therefore, the object of the present invention is to eliminate the above-mentioned drawbacks and to provide a system in which two types of data are mixed: data in a fixed data format for network control protocols and data in an arbitrary data format for transfer data. In a network where data is transmitted by a terminal (node)
An object of the present invention is to provide a synchronization device that appropriately performs synchronization at startup.

In order to achieve such an object, the present invention detects a no-signal state in which no data is flowing on a transmission path, instead of the conventionally used identifier consisting of a special code or pattern signal that is easily misidentified. By using this as an identifier and configuring to start receiving fixed-format protocol data from the network, fixed-format protocol data and arbitrary-format transfer data can be reliably identified and received, and the This makes it possible to obtain accurate synchronization.

(Example) Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 2 shows an example of the configuration of a communication network system to which the synchronization device of the present invention is applied.
A is a network transmission path, b is a communication control device (terminal), and communication control device b performs data communication with another communication control device via network transmission path a. c is a processor that operates with communication control firmware, and d is a synchronous circuit (for example, composed of a one-shot circuit) that detects whether data is flowing on transmission path a, that is, whether there is a change in the data signal on a. synchronous signal identification circuit), respectively.
It is arranged within the communication control device b. Further, various types of office equipment e are connected under this communication control device b, and the office equipment e receives or transmits communication data with the network via the communication control device b.

Communication control device b has a function that can change the transmission interval of communication data p at the time of transmission using communication control firmware, and determines the appropriate timing for synchronization for a terminal (communication control device) that has just been launched. At the break in the communication sequence, the time interval until the start of transmission of the communication data p is lengthened,
It is possible to send.

Next, an example of the operation of the apparatus shown in FIG. 2 will be explained with reference to the signal waveform diagram shown in FIG.

The waveform of the data signal p on the transmission path a is input as is to the synchronous circuit d, and an output signal q indicating the presence or absence of a change state of the data signal p is generated by means such as a one-shot circuit. Output signal q is output from processor c
For example, the data is input from an I/O port and the firmware in processor c is notified.

Immediately after startup, the processor c of terminal b continues to monitor the output signal q of the synchronous circuit d, and monitors the output signal q of the synchronous circuit d after the signal p on the transmission line a is cut off, that is, after the output signal q of the synchronous circuit d falls. Start measuring time.
When the signal p does not appear on the transmission line a even after a predetermined period of time t _s has elapsed, the processor c determines that this is the timing to perform the above-mentioned synchronization, and from that time point T, the data The system switches to reception or transmission system r, and the communication synchronization process ends.

In this way, since terminal b, which has already been started up and is in communication operation, can change the transmission interval of communication data p,
Terminal b, which has just been started and is not yet synchronized, can be guided to a suitable timing for synchronization, and as a result, in addition to the aforementioned basic transmission rate and fixed format protocol data, it is possible to communicate in any format at any transmission rate. It is possible to reliably perform synchronization processing in a network where data is mixed.
For example, by placing the synchronization timing t _S described above before the transmission of fixed format protocol data at the basic transmission rate, the first data encountered by terminal b immediately after startup after synchronization will always be Since it is guaranteed that the data is protocol data with a known format, it becomes possible to interpret the received data according to established rules. Alternatively, by placing this synchronization timing t _S at the end of a series of communication sequences, it is possible to ensure synchronization at the beginning of a new communication sequence, thereby eliminating the skip processing required when synchronization occurs from the middle of a communication sequence. I can do it.

(Effects) As explained above, according to the present invention, the special code for synchronization that is easily misrecognized, which has been used in the past,
Instead of the SYNC signal, it is configured to detect and measure the no-signal state between communication data signals and use it as a synchronization signal, so it is possible to reliably synchronize the transmission of communication data of any format. As a result, the present invention provides a great advantage in that the terminal (communication control unit) is freed from the obligation to conform its transmitted and received data to a fixed data format on the conventional network side.

[Brief explanation of the drawing]

Figure 1 is a data format diagram showing an example of the HDLC format configuration of serial communication data used in a conventional network system, and Figure 2 is a data format diagram showing an example of the configuration of a network system to which the synchronization device of the present invention is applied. FIG. 3 is a timing chart showing an example of signal waveforms during synchronization processing of the device shown in FIG. 2. a...Network transmission path, b...Communication control device (terminal), c...Processor, d...Synchronization circuit,
e...office equipment, p...network transmission data, q...output signal of synchronization circuit d, r...timing signal representing synchronization timing, _tS ...predetermined time for synchronization.

Claims (1)

[Scope of Claims] 1. Two types of communication data, fixed format protocol data and arbitrary format transfer data, are transmitted on the same transmission path, and when the fixed format protocol data is transmitted, the above-mentioned communication data is transmitted on the transmission path. A synchronization device for a network system that transmits data after a no-signal state in which no communication data is flowing continues for a predetermined period of time, which detects the no-signal state in which no communication data is flowing on the transmission path, and calculates the duration of the no-signal state. Synchronization characterized by comprising a measuring means for measuring, and a reception processing device means for performing reception processing of the fixed format protocol data when the time width measured by the measuring means reaches the predetermined time. Device.