JPS6013628B2 - Multiple data frame transmission method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides, for example, a high-level data link control procedure (H
The present invention relates to a multiple data frame transmission system that can display the type of data frame in a data frame transmission system that transmits and receives data on a frame-by-frame basis, such as DLC.

Conventionally, as a data frame transmission method, for example, a high level data link control procedure is known, and data is transmitted and received using the frame format shown in FIG.

The frame shown in the figure includes, for example, a flag sequence F (hereinafter referred to as F pattern) consisting of a bit pattern of "Oil1111", an address field A having an 8-bit structure,
, a control field C consisting of 8 bits, information fields 1 and 16 which are areas of bit sequences of transmission data.
It consists of a bit-structured frame check sequence FCS. The F pattern is attached to the beginning and end of the data frame, and the maximum bit length of information field 1 is determined by system regulations. Therefore, the length of data that can be transmitted in one frame is limited. For example, when transmitting long data such as facsimile data, the data corresponds to the maximum bit length of information field 1. It was necessary to decompose the data into the specified bit length, add an address field A and a control field C, and construct a data frame. In addition, if the maximum bit length of information field 1 specified by the system is long, the receiver can control the maximum bit length of information field 1 specified by the system and the address field length even when receiving short data. It is necessary to secure a buffer area corresponding to the sum of the field lengths, which has the disadvantage that the buffer cannot be used effectively.
The present invention improves the above-mentioned drawbacks, and uses a plurality of specific patterns as the start pattern of a data frame, and uses a combination of these patterns to display the type of data frame, thereby simplifying control of transmission and reception. The purpose is to

Examples will be described in detail below. In the present invention, as the start pattern of the data frame, F
Pattern only or f pattern and n as shown in Figure 2
(any integer including 0) F patterns are used.

The f pattern can be a discard pattern having a bit sequence of 7 to 14 consecutive "1"s, but it is of course possible to have a bit sequence different from the discard pattern. Such a relationship between the f pattern and the abandonment pattern is defined in advance between the transmitter and receiver.
As the start pattern of the data frame described above, the type of data frame is represented by an F pattern alone or a combination of an f pattern and n F patterns, and after the start pattern of the data frame, address field A, control field C, information field 1, frame Check sequence F
It sends out CS and F patterns. There are various types of data frames mentioned above, but
For example, if the bit length of a data frame is used as the type of data frame, the transmitter side can set the bit length of the data frame in F pattern alone as shown in Figure 1, or in combination with F pattern as shown in Figure 2. The data to be transmitted is displayed using 0 or more F patterns followed by 1 data.
Send by data frame.

On the receiver side, when receiving the start pattern of a data frame, it identifies whether it is an F pattern or an f pattern, and if it is identified as an F pattern,
A data frame is set in the buffer area defined by the system according to the F pattern. If it is identified as an f-pattern, the bit length of the data frame is determined by counting the number of F-patterns received following the f-pattern, and the buffer area in which the data frame is set is determined based on this determination result. Allocate and set a data frame in this buffer area. In this case, how the bit length of the data frame corresponds to the start pattern of the data frame that displays it can be freely set as a contract between the transmitter and the receiver. FIG. 3 shows the type of data frame at the time of transmission by the start pattern of the data frame, and at the time of reception,
It is a block diagram showing the configuration of a transmission control function unit having a function of identifying the type of data frame by the start pattern of the data frame. , a specific pattern generation detection section 30, a "0" insertion/removal section 31, and a frame check sequence calculation check section 32 (hereinafter referred to as an FCS calculation check section).

), an interface line 4 with other processing devices (not shown), and a data line 5. Specific pattern generation detection unit 3: F pattern, f pattern, abandonment pattern, and communication termination pattern (hereinafter these patterns are collectively referred to as specific patterns).

), and the “0” insertion/removal unit 3
1 is for transparent transmission, so when transmitting data with 5 or more consecutive 1's, a 0 is inserted every 5 1's, and the inserted 0's are removed when receiving. The FCS calculation check unit 32 also performs a frame check sequence F for the transmission data frame.
Error checking is performed by adding CS and checking the frame check sequence FCS of the received data frame. The transmission control function section 6 shown in FIG.
An example of the operation of a transmitter and a receiver equipped with the following will be described in the case where the bit length of a data frame is made to correspond to the type of data frame.

In the transmitter, after the data link is established, the control unit 1 manages the state in which data can be transmitted as a state variable "0".

In this case, if there is no data to be transmitted, the control unit 1 controls the specific pattern generation detection unit 30 in the character calculation unit 3 to generate the F pattern and send it to the data line 5. When the state variable is "0", that is, when transmission is possible and there is a request to send data via the interface line 4, the control unit 1 transfers the data sent via the interface line 4 to the sending/receiving buffer. Set it in section 2. - Also, in this case, since the bit length of the transmission data is also sent via the interface line 4, the control unit 1 can know the bit length of the data, and based on this, the control unit 1 can The specific pattern generation detection unit 30 is controlled to generate an F pattern alone or an f pattern and zero or more F patterns following it as a starting pattern of the data frame in order to display the bit length of the data frame. As mentioned above, the correspondence between the bit length of a data frame and the start pattern of the data frame that displays it can be freely set between the transmitter and the receiver. However, for example, it can be done as follows: When a short data transmission request is applied to the control unit 1 via the interface line 4, the control unit 1 requests the specific pattern generation detection unit 30 to generate the F pattern and changes the state variable to “1”. .

Also, when a long data transmission request is added, the control unit 1
requests the specific pattern generation detection unit 30 to generate an f pattern, and then requests the generation of a system-defined number of F patterns depending on the bit length of the data, and changes the state variable to "2". It is assumed that the control unit 1 does not accept a data sending request when the state variable is other than "0". If an F pattern or an f pattern followed by zero or more F patterns is generated as the starting pattern of a data frame and sent to the data line 5, the data set in the transmission/reception buffer section 2 will be “0” insertion/removal section 3
1 inserts “0” associated with transparent transmission,
Then, the FCS operation check unit 32 starts transmitting the data frame to which the frame check sequence FCS is added next to the information field 1.

When the transmission of the data frame is completed, the control unit 1 requests the specific pattern generation detection unit 30 to generate the F pattern, and causes the F pattern to be transmitted again to the data line 5.
Return the state variable to "0". In addition, if data yield is discovered during data frame transmission, a system that equates an f-pattern with an abandonment pattern will use an f-pattern, and a system that distinguishes an f-pattern from an abandonment pattern will use an f-pattern. , by sending an abandonment pattern, it is possible to cause previously sent data frames to be abandoned.

In this case, the management of the state variables shall be defined by the system, but for example, following the sending of the abandonment pattern or the f pattern, the F pattern is sent and the state variable is set to ``0''.
” is one way. When terminating the communication with the receiver, the control unit 1 controls the specific pattern generation detection unit 30 to generate a communication termination pattern consisting of 13 consecutive “1” bits or more. Send to data line 5. The above has described the operation of the transmission control function section 6 when transmitting a data frame. Next, the operation of the transmission control function section 6 when receiving a data frame will be explained. In the receiver, the control unit 1 controls the data IJ
After the link is set, the state in which data can be received is managed as a state variable "0". When the state variable is "0" and the specific pattern occurrence detection section 30 detects the F pattern, the control section 1 keeps the state variable at "0". When the state variable is “0”, the control unit 1 performs the following as shown in FIG.
When it detects that a data frame has been sent following the F pattern, it changes the state variable to "1" and requests the sending/receiving buffer unit 2 to reserve a buffer area of the size specified by the system. do. If the state variable is "1", until the next specific pattern is detected,
A "0" insertion/removal section 31 removes "0"s inserted in response to transparent transmission from the received data sent via the data line 5, and an FCS operation check section 32 performs a frame check sequence (FCS). Check it and set it in the transmission/reception buffer unit 2. During this time, the control unit 1 holds the state variable as "1",
When the specific pattern generation detection section 30 detects the F pattern, it changes the state variable to "0" and processes the received data set in the transmission/reception buffer section 2 as a data frame until the F pattern is detected. in this case,
If the specific pattern occurrence detection section 30 detects the f pattern or the discard pattern before detecting the F pattern, the control section I discards the received data set in the transmission/reception buffer section 2 that is currently being received. Management of the state variables in this case is determined by the system, but for example, if the next time the F pattern is detected by the specific pattern occurrence detection unit 30, the state variables are set to "0" and returned to the initial state. That's one way to say it. Next, the state variable of control unit 1 is “0”
The operation of the transmission control function unit 6 when the f pattern or abandonment pattern is detected in this case will be explained.

In a system that distinguishes between f-patterns and abandonment patterns, when the specific pattern occurrence detection unit 30 detects an abandonment pattern, the control unit 1 maintains the state variable as “0” and detects the f-pattern. If so, change the state variable to "2".

In addition, in a system that equates the f pattern with the abandonment pattern, when the f pattern and the bit pattern representing the abandonment pattern are detected, the control unit 1 sets the rice condition variable to "2".
”. When the state variable is “2” and the specific pattern occurrence detection unit 30 detects the F pattern, the control unit 1
adds 1 to the F pattern reception number counter (not shown) provided in the control unit 1, and when the count value of this F pattern reception number counter is smaller than the maximum number of F pattern receptions specified by the system, the The machine number is kept at "2", and when it becomes larger than the maximum number of F pattern receptions specified by the system, the state variable is set to "0" and returned to the initial state.

When the specific pattern generation detection unit 30 detects an f pattern or an abandonment pattern while counting the number of F patterns, the control unit 1 sets the F pattern reception number counter to zero. Management of the state variable in this case is determined by the system, but for example, the next time the F pattern is detected by the specific pattern occurrence detection unit 30, the state variable is set to "0",
One method is to return to the initial state. The count value of the F pattern reception number counter is the F pattern specified by the system.
When the number of pattern receptions is smaller than the maximum number of received patterns, when a data frame is detected following the F pattern, the control unit 1' changes the state variable to "3" and creates a buffer of a size corresponding to the power/count value of the F pattern reception number counter. Send/receive buffer to hold area. request to part 2,
At the same time, the count value of the F pattern reception number counter is set to zero.

When the state variable is "3", the "0" insertion/removal unit 31 inserts a "0" into the data sent via the data line 5 due to transparent transmission until the next specific pattern is detected. Then, the FCS operation check section 32 checks the frame check sequence FCS, and the received data is set in the transmission/reception buffer section 2. During this time, the control unit 1 holds the state variable as “3” and detects the F pattern by the specific pattern generation detection unit 30.
When detected, the state variable is changed to "0", and the received data set in the transmission/reception buffer section 2 until the F pattern is detected is processed as a data frame.
In this case, if the specific pattern generation detection section 30 detects the f pattern or the abandonment pattern before detecting the F pattern, the control section 1 discards the received data set in the transmission/reception buffer section 2. Management of the state variable in this case is defined by the system, but one method is to set the state variable to "0" the next time the F pattern is detected, for example. Further, when the specific pattern occurrence detection unit 30 detects a communication termination pattern, the transmitter side interprets that the data transmission has been terminated.

In the embodiments, the bit length of the data frame was explained as the type of data frame, but the present invention can also be applied to cases where the priority of the data frame is used as the type of data frame. Of course.

As explained above, the present invention uses a plurality of specific patterns as the start pattern of a data frame and displays the type of data frame by a combination of these patterns. Therefore, for example, the transmission of long data and short data can be If they are mixed, by making the type of data frame correspond to the bit length of the data frame, the transmitter side can transfer long data as is. It has the advantage of being able to omit the process of decomposing it into long pieces and cutting it down into data frames.

Furthermore, on the receiver side, since it is possible to identify whether data is long or short based on the start pattern of the data frame, there is an advantage that the buffer area can be used effectively. In particular, according to the present invention, the frame length etc. are indicated before the address field A, control field C, and information field 1 that need to be buffered, so the buffer area can be secured with plenty of time. In addition, in the specific pattern constituting the start field, unlike frames after address field A, "0" is not inserted after a predetermined number of consecutive "1"s.
Compared to the case where the frame length is sent as data, there is also the effect that the frame length can be detected earlier by the processing time required to remove "0" to identify the data on the receiving side.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram showing the frame format used in the conventional and embodiments of the present invention, Figure 2 is an explanatory diagram showing the frame format used in the embodiment of the present invention, and Figure 3 is a block diagram of the transmission control function section. It is a line diagram. F is a flag sequence, A is an address field, C is a control field, 1 is an information field, FCS is a frame check sequence, f is a flag sequence for data frame start pattern, 1 is a control section, 2 is a transmission/reception buffer section, 3 is a character 4 is an interface line, 5 is a data line, 6 is a transmission control function section, 30 is a specific pattern generation detection section, 31 is a "0" insertion/removal section, and 32 is a frame check sequence calculation check section. 1 figure, 2 figures, 3 figures

Claims (1)

[Claims] 1 Data frame transmission in which data is transmitted frame by frame, and the transmitter side inserts 0s to prevent more than a predetermined number of consecutive 1s in frames after the start pattern, and the receiver side removes them. In this method, the transmitter side uses a plurality of specific patterns as the starting pattern of a data frame, displays the type of data frame by a combination of the plurality of specific patterns, transmits the data frame, and sends the data frame to the receiver side. The multi-dimensional data frame transmission method is characterized in that the type of data frame is determined by receiving a start pattern of the data frame and detecting the number of repetitions of the specific pattern.