JPH01149635A - Data transmitting system - Google Patents

Abstract

PURPOSE:To make a data transmitting process possible even in a state where the CPU of a receiving device continuously inhibits interruption processing for a time longer than the time required for transmitting information of one character quantity by utilizing a time during which no information transmission is performed by causing transmission starting information to be transmitted before a transmitting device starts information transmission. CONSTITUTION:In a transmitting device 1, a signal synthesizing circuit 3 successively outputs transmitting information inputted from a transmitting information producing circuit 5 to a signal transmitting circuit 2 after the circuit 3 outputs transmission starting information, which is different from the transmitting information, inputted from a transmission starting information producing circuit 4 to the circuit 2. The circuit 2 outputs the transmitting information 22 after every (n) pieces of the transmission starting information 21 to a receiving device 8 through a transmission line 7. The signals transmitted to the device 8 are inputted to a transmission starting information detecting circuit 10 and transmitting information detecting circuit 11 through a signal receiving circuit 9. Upon detecting one or more pieces of transmission starting information, the circuit 10 informs the circuit 11 of the start of the reception of the transmitting information. When the start of the reception is informed, the circuit 11 is set to a transmitting information receivable state and starts reception of the information.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a data transmission system consisting of a data transmitting device and a data receiving device controlled by a CPH. [Prior Art] Conventionally, this type of data transmission system Now, the data transmission device (
Typically, a transmitting device (hereinafter referred to as a transmitting device) initiates an asynchronous C2 information transmission to the operation of a data receiving device (hereinafter referred to as a receiving device). Therefore, the receiving device always operates in a state where it can receive transmitted information.

[Problem that the invention seeks to solve]

In the conventional data transmission method described above, even when the transmitting device is not transmitting information, the receiving device needs to be able to receive information. Here, the CPU that controls the receiving device may be in a state in which the transmitted information cannot be detected for a longer time than the time required to transmit information for one character, which is determined by the received information transmission speed. At this time, the receiving device may not be able to receive part of the transmitted information.

[Means for solving problems]

The present invention provides a data transmission system consisting of a transmitter and a receiver, in which the transmitter sends a plurality of specific characters (hereinafter referred to as transmission start information) that are not used in the transmission information before starting transmission of the transmission information. The receiving device includes means for generating and transmitting the transmission start information, and is characterized in that the reception device has means for detecting the transmission start information and becomes capable of receiving the transmission information when one piece of transmission start information is detected.

〔Example〕

FIG. 1 is a block diagram simplifying the configuration of a transmitting device and a receiving device according to the present invention, and shows only the components necessary to explain the present invention.

FIG. 2 shows a data transmission format transmitted from the transmitter 1 in FIG. 1 to the receiver 8 via the transmission path 7.

In FIG. 1, when there is information to be transmitted, the control circuit 6 first activates the transmission start information detection circuit 4. Transmission start information generation circuit 4 generates n pieces of transmission start information and outputs them to signal synthesis circuit 3. Control circuit 6 then activates transmission information generation circuit 5. The transmission information generation circuit 5 generates transmission information and outputs it to the signal synthesis circuit 3. here.

It goes without saying that the transmission start information is different from the transmission information. The signal synthesis circuit 3 outputs the transmission start information inputted from the transmission start information generation circuit 4 to the signal transmission circuit 2, and then outputs the transmission information inputted from the transmission information generation circuit 5 to the signal transmission circuit 2. The signal transmission circuit 2 is
As shown in FIG. 2, n pieces of transmission start information 21 and transmission information 22 are output from the transmitting device 1 to the receiving device 8 through the transmission path 7 in this order. In FIG. 2, Tv is the free transmission time.

The signal transmitted to the receiving device 8 is input to the transmission start information detection circuit 10 and the transmission information detection circuit 11 via the signal reception circuit 9. When the transmission start information detection circuit 10 detects one or more pieces of transmission start information, it notifies the transmission information detection circuit 11 of the start of transmission information reception. The transmission information detection circuit 11 that has been notified of the start of transmission information reception enters a transmission information reception enabled state and starts receiving transmission information. The transmission information received by the transmission information detection circuit 11 is as follows.

The transmitted information is stored in the memory circuit 12. When the transmission information detection circuit 11 completes receiving the transmission information.

It will be unable to receive information until it is notified of the start of the next transmission.

In addition, in the receiving device 8, the interrupt prohibition time by the CPU is shorter than the duration time of n pieces of transmission start information. Then, while the transmission start information detection circuit 10 notifies the transmission information detection circuit 11 of the start of transmission information reception, the CPU does not disable interrupts. Even if transmission start information is detected while interrupts are disabled by the OPU, interrupts will have been disabled by the time the nth transmission start information is detected.
A situation where part of the transmitted information cannot be received does not occur.

〔Effect of the invention〕

As explained above, in the present invention, the transmitting device transmits information 1;
By transmitting the transmission start information in advance, even if the CPU of the receiving device uses the time when no information is being transmitted to continuously prohibit interrupt processing for a period longer than the time required to transmit one character's worth of information. processing becomes possible.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of a data transmission system according to the present invention, and FIG. 2 shows a data transmission format according to the present invention. In the figure, 1 is a transmitting device, 8 is a receiving device, Tv is transmission idle time, 21 is n pieces of transmission start information, and 22 is transmission information.

Claims (1)

[Claims] 1. In a data transmission system consisting of a data transmitting device (hereinafter referred to as the transmitting device) and a data receiving device (hereinafter referred to as the receiving device), the transmitting device transmits information used in the transmitted information before starting transmission of the transmitted information. The receiving device includes means for generating and transmitting a plurality of specific characters (hereinafter referred to as transmission start information) that are not transmitted, and the receiving device has means for detecting the transmission start information, and when detecting the transmission start information, transmits the transmission start information. A data transmission method characterized by the ability to receive information.