JPS6231389B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a communication control method in data communication.

A data communication control device, such as a packet switch or a packet multiplexer, which sends and receives data to and from a communication line while performing processing based on transmission control procedures such as HDLC procedures, has a central control section, a main storage section, and a communication control section. The configuration has been widely adopted. The central control unit does not directly control data transmission and reception operations with the communication line, but edits command words, that is, command words, for causing the communication control unit to perform data transmission and reception operations with the communication line, and stores them in the main memory. to start the communication control section.

When the communication control unit receives activation from the central control unit, it retrieves a command word stored in the main memory, starts sending and receiving data to and from the communication line according to the command word, and communicates between the communication control unit and the main memory. Transfers transmitted data or received data during the period. The command word has a flag indicating a chain command, and when the communication control unit completes execution of the command word specified by the chain command, it subsequently executes the next command word. In this way, an operation is performed by chaining command words, and after completion of execution of command words for which no chain command is specified,
The state completed for the first time is stored in the main memory as a status word, and a completion report is sent to the central control unit.

However, the central controller has no knowledge of the execution status of a chain command when the communication controller is executing a series of command words for transmission to which a chain command is directed. For this reason, when the central control unit needs to instruct the communication control unit to execute another transmission command word, it waits for a completion report from the communication control unit that has completed the execution of a series of command words, and then instructs the communication control unit to execute another transmission command word. This system cannot handle the case where the execution of the other transmission command word is more urgent than the execution of the current command word.

Conventionally, as a solution to this problem, a method has been adopted in which the central control section immediately resets the current transmission operation of the communication control section. It is extremely difficult to detect and determine the state of the parts. For this reason, there is a drawback that restarting the interrupted transmission operation after completion of execution of the other urgent transmission command word is extremely complicated.

The present invention has been made in view of the above-mentioned conventional drawbacks, and its purpose is to interrupt chained command words even if they are being executed, and to prioritize execution of another command word that requires more urgency. Another object of the present invention is to realize a communication control method that can easily restart an interrupted communication.

The details of the present invention will be explained below with reference to Examples.

FIG. 1 shows an example of the basic configuration of a data communication control device used in an embodiment of the present invention, in which 1 is a central control section, 2 is a main storage section, and 3 is a communication control section, which are common to each other. They are connected via a bus 100. 10
1 and 102 are from the central control unit 1 to the communication control unit 3
A control line 30 is a register for setting a suspension instruction flag received from the control line 102, and a control line 103 is a register used by the communication control unit 3 to send a completion report to the central control unit 1. This is an interrupt control line for reporting interruptions. Below, the first
The operation when the data communication control device shown in the figure performs transmission to a communication line will be explained step by step.

The central control unit 1 edits one or more command words for the communication control unit 3 to perform a transmission operation, stores them in an area 20 in the main storage unit 2, and edits the first command word to be executed first. The address is stored in the command address word area 21. Subsequently, the central control section 1 activates the communication control section 3 via the control line 101. When the communication control unit 3 receives the activation, the communication control unit 3 stores the command address word area 2 in the main storage unit 2.
1, the storage address of the command word to be fetched is first recognized, and the command word is fetched from within the area 20.

This command word has a command type 40, a chain command instruction flag 41, and various parameters 42 such as the storage address of the transmission data and the number of transmission bytes, as shown in the configuration example of FIG. Therefore, when the chain command instruction flag 41 is set in the current command word, the control unit 3, upon completing the current command word, starts the command word next to the current command word in the area 20 in the main storage unit 2. Execute. Once activated in this way, the communication control section 3 can chain and execute a series of command words. Communication control unit 3
When the execution of one command word is completed, the chain command instruction flag 41 is checked, and if the chain command instruction flag 41 is set, the interrupt instruction flag in the register 30 is further checked.

First, the operation of the communication control section when the chain command instruction flag 41 is not set will be explained. In this case, since the executed command word is the final command word, the completed state is stored as a status word in the area 22 in the main storage unit 2, and a completion report is sent to the central control unit 1 via the control line 103. Let's do it.

An example of the structure of the above-mentioned status word is shown in FIG. The status word has a completion report instruction flag 50 and an interruption report instruction flag 51 that indicate the cause of interruption when reporting by an interrupt.When reporting completion, the completion report instruction flag 50 is set, and when reporting an interruption, the interruption report instruction flag 51 is set. Set flag 51. The completed command word address 52 is the main memory 2 in which the last command word that has completed execution is stored.
Indicates the first address within. For example, in the case of an interruption report, this completed command word address indicates the starting address where the last command word completed at the time of interruption is stored.

Next, the operation of the communication control section 3 when the chain command instruction flag 41 is set will be explained. In this case, the communication control section 3 is the central control section 1
The interrupt instruction flag in the register 30 is checked to see if there is an interrupt instruction from the register 30, and if the interrupt instruction flag is not set, the next command word to be executed is fetched and executed. When the interrupt instruction flag is set, the status word is stored in the area 22 in the main memory 2, the interrupt instruction flag in the register 30 is reset, and an interrupt is sent to the central controller 1 via the control line 103. , report an interruption. The status word in this case has the interruption report instruction flag 51 set and has the start address of the last command word completed at the time of interruption.

In this way, when the communication control section 3 receives an interruption instruction from the central control section 1, it can interrupt the operation when the command word being executed is completed. In order to cause the communication control unit 3 to resume the interrupted transmission operation, the central control unit 1 decodes the status word stored in the area 22 in the main storage unit 2 at the time of interruption,
By using the interruption report instruction flag 51 and the completed command word address 52, it is recognized that the command word stored at the address indicated by the completed command word address 52 has been executed and is in the suspended state, and the completed command word address is 52
The start address of the command word next to the command word stored at the address indicated by is stored in the command address word area 21, and the communication control unit 3
Start. As a result, the communication control unit 3 starts execution from the command word next to the last command word completed at the time of interruption, making it possible to resume the execution at the interruption point.

As described above in detail, the present invention is configured such that the communication control unit completes the transmission operation upon completion of execution of the current command in accordance with the interruption instruction from the central control unit, so that the transmission operation can be quickly interrupted. Furthermore, since the state at the time of interruption is stored as a status word, there is an advantage that the interruption can be resumed very easily.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of the basic configuration of a data communication control device used in an embodiment of the present invention, and FIGS. 2 and 3 are conceptual diagrams showing examples of the configuration of a command word and a status word, respectively. . DESCRIPTION OF SYMBOLS 1...Central control unit, 2...Main storage unit, 3...Communication control unit, 20...Command word area, 21...
...Command address word area, 22...Status word storage area, 30...Suspension instruction flag register, 100...Common bus, 101...Start instruction control line, 102...Suspension instruction control line, 103...
...Interrupt control line, 40...Command type, 41
...Chain command instruction flag, 42...Various parameters, 50...Completion report instruction flag, 51
. . . Interruption report instruction flag, 52 . . . Completion command word address.

Claims (1)

[Claims] 1. In a data communication control system in which data communication control devices equipped with a central control unit, a main storage unit, and a communication control unit are interconnected via a communication line to transmit and receive data, communication activated by an activation command from the central control unit When a control unit is transmitting via a communication line by executing chained command words and receives an interrupt instruction from the central control unit, the communication control unit completes the operation related to the current command word. The communication control system is characterized in that the transmission operation is interrupted at the moment when the transmission operation is stopped, the state at the time of the interruption is stored in a main storage unit as a status word, and then an interruption report is sent to a central control unit.