JPS6086941A - Data transmission system - Google Patents

Abstract

PURPOSE:To improve the transfer efficiency of data by performing transmission and reception of data according to an abbreviated synchronizing signal in case no data to be transmitted to a remote station exists. CONSTITUTION:A synchronizing time slot clock is sent to a remote station 1 from a central control part 10 via a synchronizing star coupler 2. The time interval equivalent to the 1-frame length of a synchronizing signal has no change in case the transmission data sent from the station 1 exists in time slots of all channels. While a pass command is transmitted from the station 1 if the station 1 has no transmission data. When a pass command is detected, the clocks equivalent to a time slot are subtracted at the part 10. Then the time slot is reduced by the prescribed length, and the synchronizing signal is transmitted to all stations 1. Each station 1 performs transmission and reception of data in response to the abbreviated synchronizing signal.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to N:M transmission control, and more specifically, the present invention relates to N:M transmission control, and more specifically, to communication between a plurality of remote stations and a star coupler as a signal branching means. The present invention relates to transmission control when there is no data to be transmitted to a remote station in a data transmission system having a central control unit that is connected to remote stations and controls transmission and reception of data between remote stations.

[Background of the invention]

In conventional N:M transmission control with a star coupler in the center, the frame synchronization clock (synchronization time slot clock) used by each remote station to determine the data transmission timing is centrally controlled as a data transfer control method between each remote station. The time slot number assigned to its own mote station is individually managed (counting management of the synchronous time slot clock) and the time slot number assigned to its own station is distributed from the remote station to each remote station via the synchronous star coupler. It is configured so that the transmission data is sent to other stations only when the assigned time slot is cycled.

There is also a method in which the synchronization code is time-divided from a central control unit to each remote station through a synchronous star coupler using a fixed timer, etc., and the data transmission timing of each remote station is controlled. -130250 Publication).

However, in these methods, when a specific remote station has data to send to another station, the data transmission timing is the same for all remote stations regardless of whether or not other remote stations are sending data. This has the disadvantage that data cannot be transmitted unless the time elapses for one time slot, that is, one frame of the synchronization signal, and the data transmission efficiency is extremely low.

[Purpose of the invention]

An object of the present invention is to provide a data transmission system that improves data transmission efficiency.

[Summary of the invention]

The present invention provides a data transmission system that includes a plurality of remote stations and a central control unit that is connected to the plurality of remote stations via a star coupler as a signal branching means and controls data transmission and reception between the remote stations. If each remote station has no data to send, it sends a bus command (command sent when there is no data to send to another station) to the central control unit, and the central control unit assigns a bus command to the remote station that sent the bus command. A synchronization signal obtained by shortening the assigned time slot by a predetermined length is sent to all remote stations, and
Each remote station, when receiving a bus command, recognizes that the time slot assigned to the remote station that sent the bus command has been shortened by a predetermined length, and transmits and receives data based on the shortened synchronization signal. That is.

[Embodiments of the invention]

Embodiments of the present invention will be described based on the drawings. 2 is a synchronous star coupler for sending a synchronous signal to each remote station; 3 is a data star coupler for transmitting and receiving data between the central control unit 10 and each remote station; 4 is a central A line 5 supplies a synchronous time slot clock (synchronization signal) sent from the control unit 10, and a line 5 connects the remote station to the data star coupler 3 and the central control unit 10.
6 is a line for sending data to the remote station of the other party via the data star coupler 3,
a data line for receiving via the central control unit 10;
7 is a line for supplying a synchronous time slot clock from the central control unit to the synchronous star coupler 2;
A line through which the central control section 10 receives the HP condensed data from the data star coupler 3, a line 9 passing data from the central control section 10 to the data star coupler 3, and a reference numeral 50 a remote station control section. 2 is distributed to each remote station 1 via the synchronous star coupler 2 in the transmission system shown in FIG. It shows the flow of synchronous time slots and the flow of data transfer on the data bus transmitted and received via the data star coupler 3. As shown in the figure, the synchronization signal sent from the central control unit 10 to each remote station 1 consists of a frame synchronization signal and time slots corresponding to the number of assigned remote stations in sequence corresponding to each remote station. There is. Each remote station 1 transmits and receives data to and from other stations within the time slot assigned to it.

Next, FIG. 3 shows the specific configuration of the central control section.

In FIG. 3, 11 is a subtraction clock number setting circuit that sets the number of subtraction clocks (one time slot clock number or less) when a bus command is received from each remote station 1;
2 is a frame length initial value setting circuit for setting the number of synchronized time slot clocks according to the number of remote stations 1 connected to the central 1i1i control unit 10; 13 is a subtraction counter 14 with preset for subtracting the number of synchronized time slot clocks; A subtraction circuit 14 subtracts the contents of the subtraction clock number setting circuit 11 from the contents of the subtraction clock number setting circuit 11. A subtraction circuit 14 is given the contents of the frame length initial value setting circuit 12, and manages and sends out a synchronous time slot clock according to the contents (one frame length). 15 is a bus command detection circuit that detects bus commands sent from each remote station 1; 16 is a clock oscillation circuit that sends out a synchronous time slot clock;
17 is a synchronization signal addition circuit that adds a frame synchronization signal (sYN code) at the timing managed by the preset subtraction counter 14; 18 is the content of the frame length initial value setting circuit 12 when the preset subtraction counter 14 overflows; 19 is an AND gate that presets the (initial value of the counter) for each frame of the synchronization signal;
0.21 are an AND gate and an OR gate that add and control a synchronization code (SYN) for each frame of a synchronization signal, respectively.
Gates 22 and 23 are a driver circuit and a receiver circuit, respectively, which transmit and receive data via the data coupler 3. .

Next, FIG. 4 shows the configuration of the remote station control section.

In the figure, 51 is an addition clock number that sets the number of clocks for one time slot to be added to the synchronous time slot clock number managed by the preset addition addition counter 53 when the remote station has no data to send to its own station. a setting circuit; 52 is an addition circuit that adds the contents of the addition clock number setting circuit 51 to the number of synchronous time slot clocks managed by the preset addition addition counter 53; 53 is a preset addition addition counter; 54 is a preset addition addition counter 53; A time slot number coincidence detection circuit 55 compares the contents of the synchronization time slot number assigned to the own station with the synchronization time slot number assigned to the own station and detects a match. 56 is a synchronization code (SYN code) detection circuit that is received every frame of the synchronization signal received from the synchronous star coupler 2, and 57 is a bus command detection circuit that has been visiting its own assigned time slot. 58 is a bus command sending circuit that sends a bus command when there is no data to be sent at a time, and a synchronization code (SYN) that is added to the beginning of the data when there is data to be sent when the own station's assigned time slot comes round. 59 is a flip-flop that synchronizes the sampling of the sending data with the clock of the synchronous signal; 60 is the bus command detecting circuit 55 that detects the bus command and adds it to the contents of the preset addition counter 53; An AND gate that presets the result of adding up the contents of the clock number setting circuit 51 into the preset addition counter 53; 81 is an AND gate; 62 is an O-gate; 63, 64 is an AND gate; 65 is data sent to a remote station. 67 is a receiving gate that receives transmission data from the remote station 1; 70 is a receiving gate that receives a synchronous time slot clock from the synchronous star coupler 2; 68.
69 are a reception gate that receives data from the data star coupler 3 and a transmission gate that transmits data to the data star coupler 3, respectively.

The operations of the central control section 10 and remote station control section 50 having the above configuration will be explained below.

First, from the central control unit 10 to the synchronous star coupler 2,
A synchronous time slot clock, as shown in FIG. 2, is sent out via the OR gate 21. This synchronous time slot clock is created as follows. That is, the duty ratio 5 output from the clock oscillation circuit 16
When the 0% clock is counted by the content preset in the preset subtraction counter 14 by the frame length initial value setting circuit 12 (the number of clocks of the synchronization signal for one frame), a synchronization code is added by the synchronization signal addition circuit 17. , one frame length synchronous time slot clock is AND
The signal is sent to the remote station 1 via the gate 20 and the OR gate 21. If the data length of one time slot sent from remote station 1 is 65 bits and the number of connected remote stations 1 is 16, then the synchronized time slot clock of one frame is (65 bits + 10 bits) x 16 = 12.
This will be the clock number of 00 shots. Note that the 10 bits are transmission delay compensation bits for radially connecting remote stations, and are variable depending on the system.

Here, as shown in FIG. 5, if data transmitted from the remote station 1 exists in the time slots of all channels, the time interval of one frame length (time slots/number of remote stations) of the synchronization signal does not change.

Next, when the bus command detection circuit 15 detects a bus command from the data received via the receiver circuit 23, the subtraction clock number setting circuit 11 presets the initially set clock number for one time slot. The contents of the subtraction counter 14 are subtracted by the subtraction circuit 13, and the result is preset into the preset subtraction counter 14 via the gate 19. Since the timing of bus command match detection is related to the data length of the bus command, for example, as shown in Figure 6, if the bus command is 3 bits of synchronization code (SYN) + 4 bits of command - 7 bits, then the timing of bus command match detection is related to the data length of the bus command. If the detection time and bus command sending margin bits are 5 bits, 7+5=12 bits of clock is the data length required for one time slot when the bus command is sent, so one time slot in the normal case is Slot - 12 pits = 63 bits, and by subtracting the number of clocks for 63 bits from the contents of the subtraction counter 14 with preset, one time slot becomes 63 bits.
The synchronization time slot clock is shortened by one bit, and the round trip time becomes faster by that amount. This state is shown in FIG. As shown in the figure, if there is transmission data in the time slot of channel 1 (CH+1) and there is no transmission data in the time slots of channel 2 to channel n, the time slots of channel 2 and below are shortened by the nox command. , if the time interval of one frame of the synchronization signal is shortened, it becomes .In contrast, as shown in Fig. 8, in the conventional system, there is data to be sent only in the time slot of channel 1, and in channels 2 to 4. Even if there is no transmission data in the time slots up to n, the time interval of one frame of synchronization (1) remains the same as when there is transmission data in the time slots of all channels.

Now, on the other hand, in the remote station control section 50, the reception gate 70
When the synchronization code of the synchronous time slot clock is received via the synchronous time slot clock and the QSYN code is detected by the synchronous code detection circuit 56, the preset addition counter 53 is reset, and the preset addition addition counter 53 is started by the next synchronous time slot clock. When the counter 53 starts counting and the time slot number matching detection circuit 54 detects a match with the time slot number assigned to each remote station 1, a signal indicating no remote station transmission data is received via the receiving gate 65. Based on this, the bus command sending circuit 57 sends the +scommand to the gate 62 via the AND gate 61.
．． 69 to the data star coupler 3. At this time, if there is data to be transmitted to the remote station 1, the transmission synchronization is performed at the 7 rive flop 59, and the gates 63 and 62
69 and sends the data over the length of a normal time slot.

On the other hand, when there is no data to be sent to the remote station 1, the bus command passes through the data star coupler 3 and returns to the central control unit 10, so that all the mote stations 1 receive the bus command. When a bus command is detected by the bus command detection circuit 55 via the receiving gate 68, the content of the initialized addition time slot clock number of the addition clock number setting circuit 51 and the preset daily calculation counter 5 are
3 is added by the addition circuit 52 and preset into the preset addition addition counter 53 via the gate 60.

Here, the number of clocks per time slot initially set in the addition clock number setting circuit 51 is related to the data length of the command / The settings are the same as those of the control unit 10. In other words, the length of the command sent from the remote station 1 is 7 bits (SYN+command)+5.
bit - 12 bits, and by adding the clock number for 75 bits (normal 1 time slot) - 12 bits = 63 pits, the number of synchronized time slot clocks of remote station I is shortened by 63 bits Ht7 control It turns out. Here, if all remote stations l transmit data, the number of synchronized time slot clocks will be 75 bits (1
12 bits x 16 units = 1200 units = 1200 units = 1200 units = 1200 units (for one remote station)
The number of synchronous time slot clocks is 192 = 192, therefore, 1200-192 = 1008 synchronous time slot clocks are shortened and -cycles are collected.

As explained above, according to this embodiment, the bus command synchronization control between the central control unit and the remote station, that is, the subtraction of the number of synchronized time slot clocks of the central control unit by the bus command, and the number of time slot clocks of the remote station are performed. By synchronously controlling the added value of , it is possible to improve the transmission efficiency of a data transmission system using a synchronous star coupler and a data star coupler.

〔Effect of the invention〕

According to the present invention, it is possible to realize a data transmission system using an N:M transmission control method that improves transmission efficiency.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a schematic configuration of an embodiment of a data transmission system according to the present invention, and FIG. 2 shows the flow of time slots distributed from the central control unit to each remote station and the data transfer on the data bus. 3 is a block diagram showing the specific configuration of the central control section 11, FIG. 4 is a block diagram showing the specific configuration of the remote station MilJ control section, and FIG. 5 is the data transmission according to the present invention. Figure 6 shows the flow of time slots and data transfer in a station where there is data to be sent out in the time slots of all channels in the system. 7 is a diagram showing a state in which the time interval of 17 rooms of synchronization signals is shortened when a bus command is sent, and FIG. 8 is a diagram showing a time slot and data transfer in the case of the conventional method. It is a diagram showing a flow. 1...Remote station, 2...Synchronous star coupler, 3
...Data star coupler, 1o...Central control section,
11... Subtraction clock number setting circuit, 12... Frame length initial value setting circuit, 13... Subtraction circuit, 14...
Subtraction counter, 15.55... Bus command detection circuit, 17... Synchronization signal addition circuit, 50... Remote station control unit, 51... Addition clock number setting circuit, 52...
Addition circuit, 53... Addition counter, 54... Time slot number/number configuration circuit, 56... Synchronization code detection circuit, 57... Bus command sending circuit. Agent Patent Attorney Tatsuyuki Unuma Figure 3 10 No. 4 Area 1+Stage 6N Transmission area

Claims (1)

[Claims] 1. It has a plurality of remote stations and a central control unit that is connected to the plurality of remote stations via a signal branching means and controls data transmission and reception between the remote stations, and the central control unit has a frame synchronization signal and a central control unit that controls data transmission and reception between the remote stations. Sequentially corresponds to each remote station, it sends out a synchronization signal with time slots for the number of allocated remote stations as one frame, and transmits data transmitted from a specific remote station for each time slot to all remote stations. In a data transmission system, each remote station sends and receives data to and from other stations in synchronization with the time slot assigned to it via a central control unit. If there is no bus command, the central control section sends the bus command to the central control section, and the central control section shortens the time slot assigned to the remote station that sent the bus command by a predetermined length, and sends out a synchronization signal to all remote stations. ,
When each remote station receives a bus command, it transmits the bus command, recognizes that the time slot assigned to the remote station has been shortened by a predetermined length, and transmits and receives data based on the shortened synchronization signal. A data transmission system characterized by: