JPH05102987A - Loop type communication system - Google Patents

Abstract

PURPOSE:To easily prepare many kinds of master frames in a loop by a method in which a transmitting station a pattern to be transmitted by a receiving station a method in which, and transmits the pattern synchronously to the master frame of the loop and the other receiving station receives data based on the synchronizing pattern. CONSTITUTION:Plural stations 11-13 are connected in the shape of a loop with transmission line 14 and connected to communication equipments 18-20 with transmission lines 15-17. The receiving station to receive the data and to output them to the equipments 18-20 according to the master frame outputs the data while putting the pattern showing frame synchronization on a specified slot on the frame of the loop. The other receiving station detects the synchronizing pattern of the master frame and receives the data, and the transmitting station to transmit the data inputted from the equipments 18-20 in the cycle of the master frame according to the slot in the frame of the loop detects the synchronizing pattern outputted by the specified receiving station and transmits the data in the cycle of the master frame of the loop. Thus, the many kinds of master frames can be easily prepared in the loop.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a loop communication system used in a local area network (LAN) or the like.

[0002]

2. Description of the Related Art An example of a conventional loop communication system is shown in FIG. This loop communication system, as shown in the figure, includes a plurality of stations 1, 2, 3
Are connected in a loop by a loop type transmission line 4. Then, to each of the stations 1, 2 and 3, the transmission line 5,
Communication devices 8, 9, 10 are connected via 6, 7.

The transmission lines 5, 6, 7 between the communication devices 8, 9, 10 and the stations 1, 2, 3 are similar to the loop type transmission line 4,
It is assumed that a number of channels exist due to time slots on a frame having a fixed cycle, and that the frame has a parent frame that can be transmitted at a fixed frame cycle.

In such a loop communication system, for example, when the communication device 9 and the communication device 10 send data to the communication device 8 every several frames, the cycles of the parent frames of the transmission lines 6 and 7 are synchronized. There is no guarantee, and the station 1 needs to monitor the parent frame period of the transmission lines 6 and 7.

As a method of solving this problem, a management station that manages the loop frame outputs a specific pattern to the loop at the same cycle as the transmission lines 5, 6, and 7, and each station identifies the parent frame cycle of the loop. There is a way to make it possible.
However, in this method, if the parent frame cycle of the connected communication device is different, the frame management station needs to separately generate the identification pattern of the parent frame in each cycle. This is not a flexible system because it is necessary to remodel the frame management station of the loop each time when the number of connected communication devices increases and the types of parent frame periods increase.

Therefore, a method is conceivable in which the synchronization pattern of the parent frame received by the receiving station of the loop, rather than the managing station of the frame, is generated. However, in this method, when there are a plurality of receiving stations for one transmitting station, the frame synchronization pattern is transmitted from a plurality of locations, and the transmitting station may rely on which synchronization pattern to transmit. I don't understand.

[0007]

As described above, in order to synchronize the parent frame with the external device, the receiving station of the loop sends the synchronization pattern of the parent frame to a plurality of receiving stations for one transmitting station. , The synchronization pattern from the receiving station is also transmitted.

Therefore, an object of the present invention is to provide a loop communication system in which no problem occurs even when there are a large number of parent frame periods and a plurality of receiving stations exist for one transmitting station. And

[0009]

In the loop communication system of the present invention, a plurality of stations are connected in a loop by a loop type transmission line, and communication is performed by a circulating frame circulating on the transmission line, and each station transmits. There is a communication channel of a frame connected to an external communication device by a path, and having a frame of the same cycle as the revolving frame and a communication frame of a parent frame in which the frames are aggregated into one frame on the transmission path. In a loop communication system in which data is transmitted from a station to a receiving station in a cycle of a parent frame, one specific receiving station that receives data from a loop and outputs the data to an external communication device using the parent frame is specified. The receiving station puts a pattern indicating the frame synchronization of the parent frame on a specific slot on the frame of the loop and outputs it to the loop. The other receiving station connected to the loop detects the synchronization pattern of the parent frame, receives data from the loop, and receives data input from an external communication device in the cycle of the parent frame in the loop frame. The transmitting station of the loop transmitting in the slot detects the synchronization pattern on the loop output by the specific receiving station, and transmits the data at the cycle of the parent frame of the loop.

[0010]

The function of the receiving station to output a pattern indicating the synchronization of the parent frame in a specific time slot of the loop, and when there is another receiving station that generates the synchronization pattern, data is received from the loop by the received synchronization pattern. The transmitting station that has the function and outputs the data to the loop detects the synchronization pattern output by the specific receiving station and outputs the synchronization pattern to the loop to perform communication in synchronization with the parent frame.
Since the synchronization pattern transmitted in a specific slot on the loop is output from one location of the receiving station for each cycle of the parent frame used for communication with an external communication device, the transmitting station outputs the synchronization pattern for each cycle of the parent frame. You only have to look at one pattern.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows the configuration of a loop communication system according to this embodiment. In the figure, a plurality of stations 1
1, 12, 13 are connected in a loop by a loop type transmission line 14. The communication devices 18, 19, 20 are connected to the stations 11, 12, 13 via transmission lines 15, 16, 17, respectively. Each station 11, 12,
13 includes a transmission unit 22 that receives data from the communication devices 18, 19, and 20 and transmits the data to the loop, and a reception unit 23 that receives data from the loop.

Here, the communication devices 18, 19, 20 and the station 1
Similar to the loop type transmission line 14, a large number of channels are present between 1, 12, and 13 due to time slots on a frame having a fixed period, and the transmission lines 15, 16 and
The 17th frame has a channel of a parent frame that can be transmitted at a constant frame period.

FIG. 2 shows the transmitting unit 22 in FIG. 1 in detail. In the figure, the data from the data input unit 41 is the input buffer 4 having the size of the parent frame.
2, transferred to the loop transmission buffer 43 and sent to the loop input / output unit 44. The address of the input buffer 42 is
External standard frame time slot counter 45
And the frame counter 46 of the standard frame.

The time slot counter 45 is counted by a frame synchronizing signal of a standard frame input from the outside and a transmission clock. In addition, the frame counter 46
Is incremented by the frame synchronization signal and cleared by the header detection signal of the parent frame from the outside. The parent frame header detection is performed by the parent frame header detection unit 47.
By monitoring the data from the data input unit 41.

The address counter 48 includes the input buffer 4
2 is used to read data, and becomes an address when the input buffer 42 is read through the address selector 50 together with the frame counter 49 on the loop side.

The loop transmission buffer 43 is associated with the loop transmission line 14 in a 1: 1 relationship, and the line switch control unit 51 associates the time slot of the external frame with the time slot of the loop. And That is, the line switch control unit 51 stores the slot number of the loop corresponding to the slot number of the external frame, and when a specific slot number is designated by the address counter 48, the slot number of the corresponding loop is output. Then, it becomes a write address of the loop transmission buffer 43 via the address selector 52.

Data reading from the loop transmission buffer 43 is performed by inputting the read address generated by the time slot counter 53 through the address selector 52, and is output to the loop input / output unit 44. .. The time slot counter 53 is incremented by the loop data output clock output from the loop input / output unit 44 and cleared by the loop frame header signal.

The loop frame counter 49 is incremented by the loop frame header signal and cleared by the parent frame identification pattern detection signal. The parent frame identification pattern detection unit 5 detects the parent frame identification pattern.
4 recognizes a pattern received from the receiving station via a specific slot of the loop.

The address selectors 50 and 52 of the input buffer 42 and the loop transmission buffer 43 are switched and controlled at the timing on the loop side by the timing signal from the timing generator 55.

FIG. 3 shows the receiving unit 23 in FIG. 1 in detail. In the figure, the data from the loop input / output unit 61 is transferred to the loop receiving buffer 62, the output buffer 63, and the data output unit 64. The parent frame header pattern creation unit 65 creates the header pattern of the parent frame and outputs it to a specific slot of the loop.
However, when another receiving station outputs the pattern, the pattern output gate 66 prohibits the output of the pattern.

The frame counter 67 for generating the parent frame counts according to the frame header signal of the standard frame of the loop, and the parent frame header pattern creating section 65.
It is cleared by the signal from. However, when there is another receiving station that generates a pattern, the synchronization pattern detecting unit 68
The sync pattern is detected by and the frame counter 67 is cleared. Reference numeral 69 is a selector for selecting a clear signal.

Data writing to the loop receiving buffer 62 is performed by inputting the write address generated by the time slot counter 70 of the loop through the address selector 71. The time slot counter 70 is incremented by the clock received from the loop and cleared by the frame synchronization signal of the loop.

The line switch controller 72 is used to associate the data in the loop receiving buffer 62 with the data to be output to the outside. That is, the line switch control unit 72
Stores the slot number of the loop and the slot number of the external output corresponding to the loop slot number. The read address of the loop receiving buffer 62 is generated according to the output of the address counter 73, and the loop address is generated via the address selector 71. It is input to the reception buffer 62.

The data write address of the output buffer 63 is generated by the address counter 73 and the loop frame counter 67, and is input via the address selector 74.

The data read address of the output buffer 63 is generated by the time slot counter 75 of the external output frame and the frame counter 76 of the external frame,
It is input via the address selector 74. The frame counter 76 is incremented by the frame header signal of the external frame and cleared by the header detection signal of the parent frame. Parent frame header pattern generator 7
7 generates a parent frame header pattern based on the count value of the frame counter 76 and the frame synchronization signal.

The address selectors 71 and 74 of the loop receiving buffer 62 and the output buffer 63 are switched and controlled at the loop side timing by the timing signal from the timing generator 78.

Thus, according to the above embodiment, data of several frame periods input from an external communication device can be communicated in synchronization with the frame period of the loop, and the receiving station can receive data in accordance with the frame period of the loop. It enables synchronous communication of the parent frame from the point.

[0029]

As described in detail above, according to the loop communication system of the present invention, a pattern transmitted from a receiving station of a transmitting station of the loop is detected and transmitted in synchronization with a parent frame of the loop, Moreover, the receiving stations other than the ones that transmit the patterns may receive the synchronization patterns. This makes it easy to create multiple types of parent frames in a loop even if there are data with different parent frame periods, and even if there are multiple receiving stations, the synchronization pattern sent from the receiving station is Since it is limited to one, synchronous communication of the parent frame becomes possible.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a loop communication system according to an embodiment of the present invention.

FIG. 2 is a block diagram showing the configuration of a transmission unit in detail.

FIG. 3 is a block diagram showing the configuration of a receiving unit in detail.

FIG. 4 is a block diagram showing a configuration of a conventional loop communication system.

[Explanation of symbols]

11, 12, 13 ... Station, 14 ... Loop type transmission line, 1
5, 16, 17 ... Transmission line, 18, 19, 20 ... Communication device, 22 ... Transmission unit, 23 ... Reception unit, 49 ... Frame counter, 54 ... Parent frame identification pattern detection unit, 65 ... ... Parent frame header pattern creation unit, 67 ...
... Frame counter, 68 ... Sync pattern detection unit.

Claims (1)

[Claims] 1. A plurality of stations are connected in a loop by a loop type transmission line, communicate with each other by a circulating frame circulating on the transmission line, each station is connected to an external communication device by the transmission line, and In the transmission path, there are a frame having the same cycle as the revolving frame and a communication channel of a parent frame in which several frames are combined into one frame. In the loop communication system for transmitting the data, one of the receiving stations that receives the data from the loop and outputs the data to the external communication device by using the parent frame is a specific slot on the frame of the loop. The pattern indicating the frame synchronization of the parent frame is output to the loop and is output to the loop. The transmitting station of the loop, which detects the synchronization pattern of the frame and receives the data from the loop, and transmits the data input at the cycle of the parent frame from the external communication device in the slot in the frame of the loop, is the specific receiving station. A loop communication system, which detects a synchronization pattern on a loop output by the device, and transmits data in a cycle of a parent frame of the loop.