JPS637699B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a system for transmitting data between stations via a half-duplex transmission line using an asynchronous uncontrolled procedure (hereinafter simply referred to as an uncontrolled procedure), and in particular, the present invention relates to a system for transmitting data between stations via a half-duplex transmission line using an asynchronous uncontrolled procedure (hereinafter simply referred to as an uncontrolled procedure). The present invention relates to a control method for interrupting the transmission operation when a reason for interrupting the transmission occurs on the secondary station side while transmitting data to the next station.

In a system that transmits data in an uncontrolled manner via a half-duplex transmission path, it is impossible for the secondary station to interrupt the transmission operation while data is being transmitted from the primary station to the secondary station. In order to provide such a transmission interruption function to an uncontrolled procedure system, a full-duplex transmission path may be provided between the primary station and the secondary station. However, in recent years, opportunities to send texts containing kanji have increased, and communication speeds of 600 bps or more (for example, 1200 bps) are required. At such high communication speeds, if you try to use a telephone line as a full-duplex transmission line, you will need a full-duplex modem, which is considerably more expensive than a half-duplex modem, and it will be more susceptible to line conditions. There was a problem that it was accompanied by disadvantages.

In view of this problem, an object of the present invention is to provide a transmission interruption control method in a system that performs data transmission in an uncontrolled manner via a half-duplex transmission line.

However, in the transmission interruption control method according to the present invention, the primary station that is transmitting data to the secondary station suspends its transmission operation for a certain period (monitoring period) at arbitrary intervals, switches to a receiving state, and the secondary station side Then, when the primary station recognizes that the monitoring period has started based on the data it received just before or the notification from the primary station,
If there is a reason for transmission interruption, the interruption data is sent to the primary station, and if the primary station receives interruption data within the monitoring period, it stops the subsequent transmission operation, and if it does not receive it, it resumes the transmission operation. It is something to do.

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an example of a system to which the present invention is applied, in which a communication control device 1 (primary station) and a printer terminal 7
This is a system that transmits data between the station and the secondary station in an uncontrolled manner through a half-duplex transmission line.

The communication control device 1 has a control circuit 2, a transmission buffer 3, and a transmission/reception circuit 4, and is connected to a telephone network 6 via a half-duplex modem 5 for the telephone network. The printer terminal 7 includes a control circuit 8, a transmission buffer 9, a transmission/reception circuit 10, a reception buffer 11, and an interrupt key 12.
It is connected to a telephone network 6 via a half-duplex modem 5 for the telephone network.

The communication control device 1 sequentially transmits the data in the transmission buffer 3 from the transmission/reception circuit 4 . During this transmission operation, the control circuit 2 generates a return code in the transmission data.
Checking for CR. When the return code is detected, the control circuit 2 transmits the return code, switches the transmitter/receiver circuit 4 to a receivable state, and starts monitoring the line. The length of this monitoring period is kept constant by a timer within the control circuit 2.

The printer terminal 7 receives data from the communication control device 1 with the transmitting/receiving circuit 10, stores it in the receiving buffer 11, and sequentially prints the data with the printer 14. Whenever it becomes necessary to interrupt the transmission operation of the communication control device 1 during printing, the interrupt key 12 on the keyboard 13 is pressed manually or automatically. When the interrupt key 12 is pressed, the interrupt data is stored in the transmission buffer 9. When the control circuit 8 detects a return code during data reception, it checks whether the transmission buffer 9 has suspended data. If there is interrupted data,
The control circuit 8 switches the transmitter/receiver circuit 10 to a transmittable state and transmits the interruption data. If there is no interrupted data, the printer 14 performs a recovery operation and waits for reception of subsequent data.

When the control circuit 2 of the communication control device 1 receives the interruption data from the printer terminal 7 during the monitoring period, it cancels the scheduled data transmission thereafter. If the interruption data is not received even after the monitoring period has elapsed, the control circuit 2 restores the transmitting/receiving circuit 4 to a transmittable state and starts transmitting subsequent data.

FIG. 2 is a timing diagram showing an example of the above operation. Communication control device (primary station) 1 transmits data 1
If there is a return code CR16 in 5, the monitoring period 17 begins immediately after the return code 16 is sent. If the interruption key 12 is pressed 19 at the printer terminal (secondary station) 7 while data 15 is being received, interruption data 20 is transmitted from the printer terminal 7 within the monitoring period 17 . Therefore, the communication control device 1 stops the subsequent data transmission operation. However, when the interruption data 20 is not transmitted, the communication control device 1 starts transmitting the subsequent data 18.

In the above explanation, since the return code CR was agreed upon between the primary and secondary stations as the start information of the monitoring period,
There was no need for the primary station to take any special measures to notify the secondary station of the start of the monitoring period. Also,
A monitoring period was inserted every time a return code appeared in the transmitted data. However, a monitoring period may be inserted at regular intervals during transmission, or the start of the monitoring period may be notified to the secondary station by some means. Furthermore, the monitoring period may be inserted when a specific character other than the return code appears in the transmitted data.

For example, as shown in the timing diagram of Figure 3,
When the communication control device (primary station) enters the monitoring period 17 while transmitting data 21, the transmission carrier 22 is lowered to switch to a receivable state. On the printer terminal (secondary station) side, when the transmission carrier 22 falls, it switches to a transmittable state and sends the interrupted data 2.
If there is 0, send it. In this way, it is also possible to use the transmission carrier to notify the primary station of the start of the monitoring period to the secondary station.

As described above, according to the present invention, it is possible to perform transmission interruption control in a system using a half-duplex transmission line in the same way as when a full-duplex transmission line is used. Furthermore, if a measure is taken to insert a monitoring period using the recovery operation time of the printer of the secondary station as described above, even if the monitoring period is inserted, a decrease in the transmission efficiency of the primary station can be prevented.

[Brief explanation of the drawing]

1 to 3 are diagrams for explaining embodiments of the present invention, FIG. 1 is a diagram showing a schematic configuration of an example of a system to which the present invention is applied, and FIGS. 2 and 3 are the same as above. FIG. 3 is a timing diagram for explaining a transmission interruption operation in the system. DESCRIPTION OF SYMBOLS 1... Communication control device, 2... Control circuit, 3... Transmission buffer, 4... Transmission/reception circuit, 5... Half duplex modem for telephone network, 6... Telephone network, 7... Printer terminal, 8... Control circuit, 9... Transmission buffer , 10...transmission/reception circuit, 1
1...Reception buffer, 12...Interruption keyboard, 14
...Printer.

Claims (1)

[Claims] 1. In a system that transmits data between stations using an asynchronous uncontrolled procedure via a half-duplex transmission line,
While transmitting data to the secondary station, the primary station interrupts its transmission operation for a certain period of time (referred to as a monitoring period) at arbitrary intervals and switches to a receivable state, and the secondary station indicates that it is in the monitoring period. Only if there is a reason for transmission interruption when recognized from the data received immediately before or notification from the primary station, the interruption data is transmitted to the primary station, and the primary station transmits the interruption data from the secondary station within the monitoring period. A transmission interruption control method characterized in that if interruption data is received, the subsequent transmission operation is stopped, and if interruption data is not received, the transmission operation is restarted.