JPH063922B2 - Communication control device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a communication control device in a communication system in which a driver and a receiver are connected to a communication line to bidirectionally transmit and receive data, and More specifically, the present invention relates to a communication control device in which a transmitting station performs a process of reading back data sent by itself to prevent an error due to noise on a communication line.

(Prior Art) FIG. 5 is a structural conceptual diagram of a communication system to which the present invention is applied. In the figure, LN is a communication line, ST1, ST
2 are communication stations connected to the communication line LN via a driver DR and a receiver RC.

In such a system, the transmitting station that transmits data to the other party carries out the flow shown in FIGS. 6 and 7.

That is, as shown in FIG. 6, the data is sent as the 1st byte and the 2nd byte each time the data is ready to be sent, but each byte is sent by itself. The data is read back, and it is sent byte by byte while judging whether it is correct or not.

As shown in FIG. 7, data is transmitted byte by byte until n bytes are reached each time transmission is enabled, and data is read back until m bytes are reached each reception is possible. Done.

(Problems to be Solved by the Invention) In the conventional system that performs such an operation, the communication control controller in the transmitting station cannot perform other work at all while performing data transmission processing, and thus is inefficient. There was a problem.

The present invention has been made in view of such a problem, and an object thereof is to reduce the load of the communication control controller in the transmission processing and to be able to perform other processing, and to perform efficient communication control. It is to realize a communication control device capable of performing.

(Means for Solving Problems) According to the present invention for solving the above problems, a communication control unit for controlling communication, a transmission register for storing transmission data in byte units, and data from the transmission register are shifted. And a transmission shift register stored therein, a transmitter for sending data from the transmission shift register to the communication line, which is controlled by the communication control unit, a receiver for receiving data on the communication line, and received data received by this receiver A reception shift register that stores the data, a reception register that stores the data from the reception shift register in byte units and sends the data to the communication control unit, and an interrupt to the communication control unit when reception data is received via the receiver. Reception interrupt means for applying the transmission data, and the communication when transmitting the transmission data through the transceiver. And a transmission register which receives an interrupt from the transmission interruption unit or the reception interruption unit and which is currently received by the receiver in byte units and a transmission register. The communication control device is characterized by comparing and checking the transmission data of 2 bytes before the current byte transmitted to the.

(Operation) The communication control unit controls the transmitter / receiver with the double buffer, and checks the data received by the receiver upon receiving an interrupt by the interrupting unit at the time of transmitting or receiving the data.

Here, the communication control unit receives (reads back) the data of 2 bytes before and checks it only at the timing when the interrupt is received from the interrupting means, so that the performance of the entire system can be improved. .

Embodiments Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a configuration block diagram showing an embodiment of the present invention. Here, only one communication station is shown. In the figure, reference numeral 1 is a communication control unit for performing communication control, and includes a microprocessor 11, a memory 12 and the like inside. Reference numeral 2 denotes a transmitter / receiver with a double buffer controlled by the communication control unit 1. The transmission register 21 stores the data to be transmitted, the transmission shift register 22, and the data from the transmission shift register 22 is sent to the communication line 3. The transmitter 23, the receiver 24 for receiving the data on the communication line 3, the reception shift register 25 for storing the data received by the receiver 24, and the reception register 26 are included.

Reference numeral 4 is a reception interrupt means for interrupting the communication control unit 1 when receiving the reception data via the receiver 24,
Reference numeral 5 denotes a transmission interruption means for interrupting the communication control unit 1 when transmitting the transmission data via the transmitter 23.

The operation of the device configured as described above will be described separately for data reception and data transmission.

(When receiving data) The communication control unit 1 disables the transmitter 23,
The transmission interruption means 5 is disabled and the reception interruption means 4 is enabled to receive the reception data from the receiver 24. The data received by the receiver 24 enters the reception shift register 25 and is sent to the communication control unit 1 side via the reception register 26 for each byte.

(During Transmission) The communication control unit 1 sends the transmission data with the transmitter 23 enabled, the transmission interrupting unit 5 enabled, and the reception interrupting unit 4 disabled. The transmission interrupt means 5 issues a transmission request TXINT to the communication control unit 1. The communication control unit 1 receives this communication request and outputs the transmission data to the communication line 3 via the transmitter 23. Further, at the same time, the data received by the receiver 24 is read and compared with the previously transmitted transmission data, whereby the communication line 3, the transmitter 23, the receiver 24
Check such as.

The above is the outline of the operation at the time of transmission, and the details will be described next.

FIG. 2 shows the transmitter / receiver 2 during transmission.
3 is a conceptual diagram showing the contents of each register in FIG. Here, the data to be sent is sent in byte units,
The first byte data is D1, the second byte data is 2,
The data of the third byte is represented as D3 ....

In (A), the data D1 of the first byte is transmitted, and the data D1 is stored in the transmission register 21.

In (B), the data D2 of the second byte is transmitted, the data D2 is stored in the transmission register 21, and the data D1 of the first byte is stored in the transmission shift register 22.

In (C), the data D3 of the third byte is transmitted, the data D3 is stored in the transmission register 21, and the data D2 of the second byte is stored in the transmission shift register 22. Further, the reception shift register 25 stores the first byte data D1 output to the communication line 3.

FIG. 3 shows a transmission interrupt TXI from the transmission interruption means 5.
9 is a flowchart of a transmission sequence executed by the communication control unit 1 in response to NT.

When the communication control unit 1 receives the transmission interrupt TXINT,
For example, N bytes of data are sequentially transmitted from the first byte (step 1). When the byte currently being transmitted is the i-th byte from the data transmission of the third and subsequent bytes, the data Di-2 of the i-2 byte is read back via the receiver 24 and the received data is checked (step 2 , 3).

This check is performed by checking in advance whether or not the data D1 transmitted via the transmitter 23 and the received data match. If an error is detected by this check, it is processed as a transmission error.

Such an operation is performed up to the final N bytes. After the N + 1th byte, no data transmission operation is performed, but the N-1th byte and the Nth byte of the received data are checked, and the transmission sequence ends (steps 4 and 5).

By executing such a sequence, the communication control unit 1 performs the data transmission and the read-back process of the transmission data in one step.
Since it is performed at the same time at the time of the transmission interruption, the processing time is not wasted as a whole, and the load on the communication control unit can be reduced.

FIG. 4 is a flowchart showing another example of the operation of the device of the present invention. In Fig. 3, at the time of transmission interruption,
The output data is read back, but in this example, the data output at the reception interrupt is read back.

In this case, the first 2 bytes are advanced. After that, the transmission and read-back operations are performed at the read-back timing.

(Effects of the Invention) As described in detail above, the present invention is such that the communication control unit checks the data received by the receiver at the time of data transmission or reception.
The number of interrupts is reduced, the load on the communication control unit can be reduced, and the performance of the entire system can be improved.

[Brief description of drawings]

FIG. 1 is a configuration block diagram showing an embodiment of the present invention, and FIG.
FIG. 4 is a conceptual diagram showing the contents of each register in the transmitter / receiver 2, FIG. 3 is a flowchart of a transmission sequence executed by the communication control unit 1 upon receiving a transmission interrupt TXINT from the transmission interruption means 5, and FIG. FIG. 5 is a flowchart showing another example of the operation of the device of the present invention, FIG. 5 is a conceptual diagram of the configuration of the communication system to which the present invention is applied,
6 and 7 are flowcharts showing the operation of the transmitting station in the system of FIG. DESCRIPTION OF SYMBOLS 1 ... Communication control unit 2 ... Transmitter / receiver with double buffer 3 ... Communication line 4 ... Reception interruption means 5 ... Transmission interruption means

Claims (1)

[Claims] 1. A communication control unit for performing communication control, a transmission register for storing transmission data in byte units, a transmission shift register for storing data from the transmission register by shifting, and control by the communication control unit. The transmitter that sends the data from the transmission shift register to the communication line, the receiver that receives the data on the communication line, the reception shift register that stores the reception data received by this receiver, and the data from this reception shift register A reception register that stores the data in byte units and sends it to the communication control unit, a reception interrupt unit that interrupts the communication control unit when receiving the reception data through the receiver, and transmits the transmission data through the transceiver And a transmission interrupt means for occasionally interrupting the communication control unit. The communication control unit receives an interrupt from the transmission interrupt unit or the reception interrupt unit, and receives the byte-unit data currently received by the receiver and the transmission data 2 bytes before the current byte transmitted to the transmission register. A communication control device characterized by comparing and checking.