JPS6032458A - Decentralized synchronism communication system - Google Patents

Abstract

PURPOSE:To decrease the reduction in transmission efficiency by superimposing a carrier signal longer than 1 bit onto the beginning of a frame and transmitting a bit data at each specified time in synchronizing with the end of the carrier signal so as to supervise the line in synchronizing with the carrier. CONSTITUTION:The respective stations of a communication system are linked by a transmission medium 1 and an external device 8 is connected to the communication control section 4 of each station. Further, the transmission medium 1 is connected to the communication control section 4 via a demodulator 3 and a receiver 2 and the transmission medium 1 is connected to the control section 4 via a modulator 7 and a driver 6. Then an oscillator 5 is connected to each control section 4. Further, a signal is superimposed respectively on the front edge or the tail edge of one bit so as to code 1, 0, and the carrier signal longer than 1-bit signal superimposed on the transmission medium 1 is transmitted to the beginning of the frame as a synchronizing signal so as to produce the frame synchronizing signal and the transmisson medium 1 is superimposed in synchronizing with the carrier signal.

Description

[Detailed description of the invention] Industrial application field The present invention is distributed to various locations and distributed for 10 times! , relates to a communication method between two devices.

Problems with the development of conventional examples Conventionally, communication between various devices required means for transmitting l1iJ1j1, and a start bit was added as a synchronization signal to synchronize data frames, and A common method is to add a synchronization header to achieve synchronization. However, the above two methods have the following drawbacks.

In the former start bit synchronization method, a state different from the normal state on the transmission line is determined as the start star 1-bit, so if a signal equivalent to start bit 1 is detected due to disturbance noise, etc. In either case, signals from other devices cannot be received during one frame period. Therefore, if the time required to transmit one frame is long, the time during which reception is not possible will naturally become longer, and the transmission effectiveness of the system will be significantly reduced.

The latter synchronization header method adds a specific synchronization character etc. first and starts synchronization upon reception of that synchronization character.With this method, by appropriately selecting the synchronization character, the synchronization character can be activated by the disturbance M sound. Since the possibility of detecting the error becomes extremely low, malfunctions are less likely to occur than in the same method using the star 1 to 1-. However, the disadvantage of this method is that a relatively long synchronization signal such as a synchronization character must be added to the frame.
When the transmission efficiency of Jl tJ l- decreases, the signal with the same pattern as the synchronization character within the frame (
'l) Since 7> is not satisfied, the degree of freedom of the frame is reduced.

OBJECTS OF THE INVENTION The present invention eliminates the degradation of transmission efficiency due to disturbance noise and increased overhead of the conventional method. The purpose is to provide fJ information methods.

Structure of the Invention The distributed synchronous communication method d1 of the present invention superimposes a carrier signal on a transmission medium tree, so that when carrying out -C communication, the leading edge of time is 'i', ``i'', ``o'' by superimposing the respective signals after H1
At the same time, a carrier signal that is longer than at least one bit time and is superimposed on the transmission medium is sent out as a synchronization signal at the beginning of the frame, and is received by the carrier signal and generates a synchronization signal for the IC frame to transmit the IC frame to the transmission medium. The above signal is a read signal.

DESCRIPTION OF EMBODIMENTS A specific embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a communication system using the synchronous communication method of the present invention. 1 [Transmission medium connecting transmission systems S1 and S2, stations 8.8'Gj and 81.82 respectively.
This is an external i-device placed in the The communication TA11 section 4 connected to the external equipment 8 at the station S1 is connected to the transmission medium 1 via a receiver 2 and a demodulator 3, as well as to the transmission medium 1 via a modulator 7 and a driver 6. A communication control unit 4' connected to an external device 8' at the station 82 is connected to the transmission medium 1 via a receiver 2' and a demodulator 3'. Further, 5° 5' are oscillators connected to the communication control units 4 and 4', respectively.

Figure 2 A, B, and C are the pano j signals to the modulator 7, respectively;
The signal on the transmission medium 1 and the output signal of the demodulator 3 are shown. Tρ is a state of no confidence, and 1-2 is a data frame.

In the station S1, the state of the transmission medium 1 is monitored by the communication control unit 4 via the receiver 2 and the demodulator 3, and if there is no communication request from the external device 8, the state of the transmission medium 1 is monitored in the Ll cycle. When the state of 1 is monitored and a carry '4n'; 3 is placed on the medium 1, first, monitoring is performed three times in the cycle of tl. If the gear Al rear signal is detected all three times, then t is shorter than the t1 cycle (monitoring is repeated in 2 cycles. The first time is synchronized with the time when the carrier signal can no longer be detected on medium 1. LL
1 on the medium is monitored at time t3 (where tl > tJ > t2) 1G, and thereafter, after time t1, the device I+1 is monitored. Since signals 1 and 1 are superimposed on the medium 1 as shown in FIG. Yes, when there is a communication request from external device 8, medium 1
G) If the carrier signal is not detected, the communication control unit 4 transmits the synchronization header by 1 pin through the modulator 7 and the driver 6.
It is sent for a time T1 which is longer than time t4, and then depending on the data to be sent, if it is 0", it is "1" as shown in the third diagram.
'', the signal is detected as shown in E. Here, both communication and reception are performed by the communication control unit 4, and the basic clock signal of the communication control unit 4 is transmitted to a crystal oscillator or ceramic oscillator such as an oscillator 5 with the same frequency. If you use tl.

Since the times t2 and t30 are extremely stable, signal synchronization between the transmitter and the receiver is performed stably.

ADVANTAGES OF THE INVENTION As described above, according to the distributed synchronous communication method of the present invention, at least one
A carrier signal that is longer than the bit time is superimposed, and the terminal end of the carrier signal is synchronized to generate a pixel at every specified time.
The line is monitored in synchronization with the carrier signal, so when communicating between multiple devices connected on the same transmission medium, it is possible to avoid noise like a one-way system. There is no reduction in transmission efficiency due to an increase in the A-bar head as is the case with the weak synchronization character method, and the data demodulation circuit can be used as is for carrier detection and signal demodulation necessary for detection of the synchronization header. It is extremely easy to do. According to the present invention
Since the νJ communication method is not limited by communication media or communication speed, it is suitable for communication between distributed devices.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a communication system according to a specific embodiment of the distributed synchronous communication method of the present invention, FIG. 2 is a diagram of signal waveforms and signal reception timing of each part of FIG. FIG. 3 is a waveform diagram of an encoded signal output from a communication control unit. DESCRIPTION OF SYMBOLS 1... Transmission medium, 2... Receiver-13... Demodulator, 4... Communication control part, 5... Oscillator, 6... Driver, 7... Modulator, 8...・External equipment, t4...
・1 bit 11 hours, T1... Time longer than 1 bit, T2... Data frame agent Yoshihiro Morimoto (l + Shima (

Claims (1)

[Claims] 1. When carrying out communication by transmitting a carrier signal on a transmission medium, a signal is superimposed on the leading edge or trailing edge of an l bit time, respectively.
11 QI+ is encoded and a carrier signal superimposed on the transmission medium that is longer than at least b1 bit time is sent as a synchronization signal at the beginning of the frame, and the -1゛1
- A distributed synchronous communication method in which the JFiJ period I1ROI1U3 of the frame received by the rehib7 signal is read and received on the transmission medium.