JPH0775363B2 - Data transmission method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of use] The present invention relates to a communication control starting means for starting data communication between devices in a configuration in which one asynchronous non-procedural terminal is connected to a central processing unit. .

〔Overview〕

According to the present invention, in a communication starting means for realizing communication between an asynchronous non-procedural terminal having an unspecified communication speed and parity form and a central processing unit, transmission / reception of the central processing unit based on two kinds of characters from the terminal. By setting the means and the parity verification means, the communication can be executed without changing the setting of the communication speed and the parity mode at the terminal.

[Conventional technology]

When performing data communication between a central processing unit and an asynchronous non-procedural terminal, conventionally, a terminal having the same communication speed and parity as the communication speed and parity set in advance in the sending / receiving unit of the central processing unit. , Or the terminal was used after setting the communication speed and parity of the terminal to the communication speed and parity of the sending / receiving unit of the central processing unit.

[Problems to be solved by the invention]

In such a conventional method, when the asynchronous non-procedure terminal is connected to the central processing unit and when the connected terminal is changed to a different terminal, the communication speed and parity of the terminal are sent to the central processing unit each time. -It is inconvenient that the communication speed and parity set in the receiving section must be set again, and there is a drawback that terminals that cannot make this setting cannot be used.

The present invention eliminates such drawbacks, and provides a starting means capable of realizing data communication between an asynchronous non-procedure terminal having an unspecified communication speed and parity and a central processing unit by simple data transmission from the terminal. An object of the present invention is to provide a data transmission method having the above.

[Means for solving problems]

The present invention has a non-synchronous non-procedural terminal for transmitting and receiving data to which a predetermined parity bit is added at a predetermined communication speed, a transmission and reception means for transmitting and receiving data at this communication speed, and a parity verification means for testing the parity bit. In the data transmission system including a processing device, the terminal has a first character corresponding to a communication speed of data transmitted from the device and a second character corresponding to a form of a parity bit added to the communication data. Is provided, the central processing unit sets the communication speed of the transmitting and receiving means based on the first character that has arrived, and
It is characterized by further comprising control means for setting the parity verification standard of the parity detection means based on the second character that has arrived.

[Action]

When the power of the central processing unit is turned on, the first character is transmitted from the terminal. The communication speed is set based on the first character. Subsequently, the second character indicating the mark, space, even number, or odd number in the parity form of the data is transmitted from the terminal, and the parity verification standard of the parity verification means of the central processing unit is set.

When this setting is completed, communication between the central processing unit and the terminal is started.

〔Example〕

 An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of this embodiment.

In this embodiment, the asynchronous non-procedure terminal 1 is connected to the central processing unit 2, and the central processing unit 2 receives the asynchronous data transmitted from the terminal 1 and the central processing for the terminal 1. A transmitter 4 for transmitting a response from the device 2,
The memory unit 6 stores a character for determining the communication speed and the parity, and the control unit 5 for determining the communication speed and the parity of the terminal 1.

Next, the operation of determining the communication speed and parity of the central processing unit 2 by the data transmission from the terminal 1 will be described based on FIGS. 1 and 2.

When the power of the central processing unit 2 is turned on, the control unit 5 instructs the receiving unit 3 to receive the data at the lowest communication speed that the central processing unit 2 can set, while the terminal 1 Send the first character. The first character is a character that can be identified by the receiving unit 3 of the central processing unit 2 as asynchronous data having the lowest speed, regardless of the communication speed of the terminal 1, and is predetermined. The control unit 5 having received the first character received by the receiving unit 3 is identified when the first character transmitted at each communication speed stored in the memory unit 6 in advance is received at the lowest speed. The communication speed of the terminal 1 is provisionally determined by comparison with the power character. At this time, since the parity has not been detected yet, the parity bit is ignored and the comparison is performed. The control unit 5 instructs the reception unit 3 to the provisionally determined communication speed, and the reception unit 3 waits for reception of the next character at the provisionally determined communication speed.

Receiving the first character from the terminal 1 again, the receiving unit 3 transfers this to the control unit 5 and compares it with the first character stored in the memory unit 6 to determine whether this character is a predetermined first character. Confirm that the character is. If the character is recognized as the first character, the tentatively determined communication speed is determined to be the communication speed of the terminal 1,
The communication speed is instructed to the receiving unit 3 and the transmitting unit 4, and the received character is stored in the memory unit 6.

On the other hand, if it is determined that the received character is not the first character, it means that either the tentatively set communication speed is incorrect or the data transmitted from the terminal 1 is not the first character. The communication speed is set to a low value, and the operation is restarted from the beginning to prevent malfunction of the terminal 1 and the central processing unit 2.

Next, based on the second character transmitted from the terminal 1, the control unit 5 identifies whether the parity of the data set in the terminal 1 is mark, space, even number, or odd number. The second character is a character that can be compared with the first character stored in advance in the memory unit 6 to determine the parity from four types of parity, and is predetermined. The control unit 5, which has received the second character from the reception unit 3, confirms that this character is the predetermined second character, and determines the parity from the parity bits of the first and second characters and the two characters. Identify.

On the other hand, when the second character is not the predetermined character, it means that the communication speed is incorrect or the data transmitted from the terminal 1 is not the second character. Settings are made and operations are restarted from the beginning to prevent malfunction of the terminal 1 and the central processing unit 2.

When the control unit 5 determines the communication speed and parity based on the character transmitted from the terminal 1, it returns a response to the terminal 1. When the terminal 1 does not receive this response, the terminal 1 transmits again from the first character. As a result, malfunction can be prevented.

[Effects of the Invention] As described above, according to the present invention, even when an asynchronous non-procedural terminal having an unspecified communication speed and parity is connected to the central processing unit, if two kinds of characters are transmitted from the terminal several times. There is an effect that data communication between the central processing unit and the asynchronous non-procedural terminal can be started.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of the embodiment of the present invention. FIG. 2 is a flowchart showing the operation procedure of the present invention. 1 ... Terminal, 2 ... Central processing unit, 3 ... Reception unit, 4 ...
... Sending section, 5 ... Control section, 6 ... Memory section.

Claims (1)

[Claims] 1. An asynchronous non-procedure terminal for transmitting / receiving data to which a predetermined parity bit is added at a predetermined communication speed, a transmission / reception means for transmitting / receiving data at this communication speed, and a parity detection means for testing the parity bit. In the data transmission system including the central processing unit, the terminal is the second character corresponding to the first character corresponding to the communication speed of the data transmitted from the own device and the form of the parity bit added to this communication data. The central processing unit sets the communication speed of the transmission / reception means based on the incoming first character, and the parity of the parity detection means based on the incoming second character. A data transmission method comprising a control means for setting a verification standard.