JPS6187444A - 2-wire type semi-duplex communication system - Google Patents

Abstract

PURPOSE:To avoid transmission of ineffective data by controlling the transmission in response to an opposite device to a transmission request to avoid the start of transmission when the reception of the opposite device is disabled. CONSTITUTION:In transmitting data from the device A to a device B, a controller CTL gives a command to transmit information representing the transmission request to a pattern generator PG. the PG transmits a character string comprising specific bit pattern BP from transmission request information to the device B via a gate OR and a data line S1. The character string comprising specific BP from the information representing the propriety of the reception of request from the device B from the data line S2 is received and stored in a register REG. When the CTL recognizes that this information is possible for reception, the data start character string is transmitted to the PG, the information representing the length of data is fed to the counter CNT and the bit string forming an optional BP from the data stored in a memory SM is fed to the device B via an OR and an S1 respectively. The device B does not receive the specific character string as a character string but as data.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention provides data communication between data communication terminals, between information processing devices, or between a terminal and an information processing device via a data line. The present invention relates to a two-wire half-duplex communication system for transmitting and receiving bit strings consisting of patterns as data.

[Conventional technology]

Conventionally, data communication systems have a transmission data line and a reception data line between two devices that communicate with each other, and characters composed of 7 bits or 8 bits are transmitted as data. A system was adopted in which the end of data transmission was indicated by a character indicating the end of the data.

Therefore, when two devices that want to communicate, such as an information processing device as mentioned above, want to send and receive a bit string consisting of arbitrary bit patterns as data, some of the bit patterns being sent and received include If a bit pattern corresponding to a character indicating the end of transmission is included, it will be interpreted as a character indicating the end of transmission rather than as data, resulting in data communication being terminated midway. However, it had the disadvantage that it was not possible to transmit a string of nodes with arbitrary bit patterns.

In addition, in conventional data communication systems, a character string (consisting of a specific bit pattern) indicating that reception is not possible or possible is determined in advance, and when that character string is sent from the other party's device during transmission, it is A method is adopted in which transmission is stopped and restarted, and as a result, data transmission is started without confirming that the other device is completely capable of receiving the required data, and as a result, There was a drawback that data communication could sometimes result in failure.

[Problems to be Solved by the Invention] Therefore, in the present invention, in the conventional data communication system, it is possible to transmit a bit string consisting of an arbitrary bit pattern as data, and to ensure that the other device can receive it reliably. The problem to be solved is to start data transmission after confirmation and to avoid sending invalid data.

Therefore, the present invention allows a bit string consisting of an arbitrary bit pattern to be transmitted and received as data between two devices, and once data transmission is started, it is always completed until the end, and there is no possibility of a failure midway through. It provides a two-wire half-duplex communication method that eliminates the

[Means and effects for solving the problem] The two-wire half-duplex communication system according to the present invention uses a data line for transmitting a bit string forming an arbitrary bit pattern as data and a data line for receiving it. are connected to each other through
When two devices communicate with each other, the device that has the data to send sends information indicating the request to send via the data line as a character string made up of a specific bit pattern, thereby requesting the data to be sent. is transmitted to the other device, and after receiving a character string also made up of a specific bit pattern from the other device via the data line as information indicating whether or not the request can be accepted, if the request is accepted, the start of the data is sent to the other device. After sending a character string as information indicating the following information and information t13 indicating the length of the data, data (a bit string forming an arbitrary bit pattern) is sent via the data line.
The other device starts sending the data, and the other device receives the following data:
The feature is that even if a bit pattern representing a specific character string is included, it is received as data without being recognized as a character string.

[Implementation (;II) The present invention will now be described in detail with reference to the drawings.

The figure is a block diagram showing one embodiment of the present invention.

8 in the same figure, A and B are devices that communicate with each other, SM
is a memory for storing data to be transmitted from device A to device B, CNT is a counter that does not indicate the amount of data stored in sM, RM is a memory for storing data to be transmitted from device B, and PG is a memory for storing data to be transmitted from device B. A character string indicating whether device A can receive information from device B, a character string indicating that device A has a request for transmission to device B, and memo 98.
A pattern generator that generates a character indicating the start of the information in M when it is sent; OR is the data sent from the memory SM, a character string sent from the pulse generator PG, and a hint of the amount of data sent from the counter CNT. The OR circuit that takes the logical sum of each and sends it to device B, REG is the transmission request character string sent from device B, and the memory RM.
A register for receiving from device B a character string indicating the start of information to be received by device B, a character string indicating whether device B is capable of receiving information, and information indicating the amount of data to be received in memory RM. , CT L is a controller that controls the overall flow of information, AND 1 is an AND 1 that takes the AND of the information tk sent from device B with the signal of controller CTL, and receives it to L sister REG. circuit, AN
D2 transmits information sent from device B to controller CTL.
This is a tent circuit for performing a logical product with a signal of , and receiving the result to the memory RM.

In addition, Sl is a data line for device A to send data or character strings to device B, s2 is a data line for device B to send data or character strings to the device, and Fl is a data line for connecting external devices to the device. A data line for writing information to the memory SM, F2 is a control line for requesting an external device or device Δ to send the contents of the memory SM, and F3 is a data line for device A to write to the memory RM. And send the contents of memory SM! , ;'L sign wa-9 Controls for notifying external devices of all ,i,'i! , 1・′4 is”,,′:
, Okihachi is a data line for transmitting the contents of the memory RM to the main unit, and cl is a data line for sequentially transmitting the contents of the memory SM (2).
TI is a control line that triggers sending data to the counter CNT, TI is a control line that writes the amount of data written in the memory SM to the counter CNT, and TI is a control line that notifies the controller CT1 of the information in the counter CNT. The line T3 is a data line for sending the contents of the counter CNT to the OR circuit OR.
T5 is a control line for notifying the controller CTL when the transmission of data in the memo 13M is completed, I)
1 is a control line that instructs the pulse generator PG to generate a character string indicating that reception is possible, F2 is a control line that instructs the pulse generator PC to generate a character string that indicates that reception is not possible, and F3 is a control line that instructs the pulse generator PC to generate a character string that indicates reception is not possible. Pulse generator P
F4 is a control line that instructs pulse generator PG to generate a character string for sending a transmission request; F4 is a control line that instructs pulse generator PG to generate a character string for starting transmission; (-:2
is a pulse generator (I) that gives an opportunity to sequentially send the character strings generated by G to the data line P5.
"C4 is the control line that triggers sending data to S3, and C4 is the data line S.
A control line C5 is input to the AND circuit ANDI to send the information sent to the data line S2 to the signal line R1, and a control line C5 is input to the AND circuit AND2 to send the information sent to the data line S2 to the signal line R2. C6 is a control line that instructs memory RM to receive the indicated amount of data from signal VAR2, and C7 is a control line that instructs controller CTL.
receives information from control cotton R1 into register REG.

A control line R3 for instructing is a control line for the controller CTL to refer to '1'f in the register REG.

Next, this operation will be explained. The external device writes data to the SM of the device through the data line F1, and then requests transmission through the control line F2.

The controller CT L for the device sends a signal to the control line P3 to instruct the pulse generator PG to generate a character string indicating a transmission request, and also sends a signal to the control line C2 to send the character string to the data string P5. The pattern sent to the data line P5 passes through the off-circuit OR, and the data line S1
is sent to device B via. At the same time, the controller CT L controls: ijl! Send a signal to C4 and C7,
The register REG receives the information sent to the data line S2 (p (1+:°1).

The controller CTL refers to the information sent via the control line R3 and determines whether it has responded to the transmission request as such.If the information in the register REG indicates that it is ready to receive If it is a character string, stop the signal on the control line P3, send a signal to the control line P4, and send the character string to start transmission to device B. When the transmission is finished, stop the signal on the control line P4, and send a signal to the control line P4. A signal is sent, and the information on the counter CNT is sent to the device B. When this is completed, the control line C3 is stopped, a signal is sent to the control line CI, and the contents of the memory SM are transmitted to the device B by the amount indicated by the counter CNT.

When the transmission is completed, the output of the signal on the control line Ct is stopped,
The external device is notified via the control line F3 that the transmission of information from the memory SM has been completed.

If the character string sent to register REG as a response indicates that reception is not possible, control lines P3°C2, C4, C
Stop signal 7 and try again after a certain period of time.

To receive data from device B, operate as follows.

Controller CTL sends signals to control lines C4 and C7,
The information sent from device B is received by register REG. When register REG receives a character string indicating a transmission request, controller CTL sends a signal to control lines PL and C2, and sends a character string to device B indicating that it is ready for reception. send.

After that, a character string indicating the start of information is received in register REc, and information indicating the amount of data to be sent is received in register REG.
After receiving that amount of data, the controller CTL instructs the memory RM via the control line C6 to receive that amount of data, and also stops the signals to the control lines C4 and C7.
A signal is sent to the control line C5, -, so that the data transmitted to the data line S2 is transferred via the AND circuit AND2 to the data line R2-. When the controller CTL is notified via the control line R4 that the data of ¥ notified from the device B has been received, the controller CTL notifies the external device of the reception of the data via the control line F3. Stop the signals on control lines C5 and CG.

〔Effect of the invention〕

2, according to the present invention, the transmission operation is controlled by the response of the target device to the transmission request.
It is not possible to start transmission when the A location is in a non-receivable state. Further, since it is not necessary to indicate the letter "R" in the transmission information t13 using special characters, it is possible to transmit information having any pattern.

[Brief explanation of drawings]

The figure is a block diagram showing one embodiment of the present invention. Symbol explanation Δ and B: Devices that communicate with each other SM: Memory for storing data to be sent to device △ or device B CNT: Does not indicate the amount of data recorded in SM Counter RM: From device B Memory PG that stores the data to be sent: A character string that indicates whether device A can receive information from device B, and a character string that indicates whether device A can receive information from device B. A pattern generator that generates a character string indicating the start of data sent from the SM and a character string indicating the start when sending data in the SM OR: Data sent from the SM, a character string sent from the PG, and each bit of information indicating the amount of data sent from the CNT OR circuit REG that calculates the logical sum of and sends information to device B: Character string of transmission request sent from device B,
A register CTL for receiving from device B a character string indicating the start of data to be received by RM, a character string indicating whether device B can receive data, and information indicating the amount of data to be received by RM. : Controller that controls the overall flow of information ANDI: AND circuit A which takes the logic and product of the information sent from device B with the CTL signal and receives it to REG 2: The information sent from device B CT information
AND circuit SL for taking the AND with the L signal and receiving it to RM; Data line S2 for device A to send data, character string, or data amount information to device B: Device B sends data to device A. , a data line Fl for transmitting a character string or data information: a data line F2 for an external device to the device to write data to the SM; a data line F2 for an external device to request the device A to transmit the contents of the SM Regulation? ff1l line F3'?
:, Goshichiya 5 whose data is in Oki△ or RM? Is there a system to notify the external device that the content of v1 has been sent?
all :f2:F4 ;Data line C1 for the device to transmit the contents of RM to the external device: Control line C2 that provides an opportunity to sequentially send the contents of SM to T4: An opportunity to sequentially send the patterns generated by the PC to P5 Control wire C3: Control line that provides an opportunity to sequentially send the contents of CNT to T3 C4: Control line that is manually input to AND l to send the emotion sent to S2 to R1 (,,,,) : A N D 2 "manual control line (1) to send the information sent to S2 to R2. Control line 07 to instruct RM to receive the instructed Sato no Kiyo Fu from R2: Control line 'T''l instructs REG to receive information from R1 (tS): Controls the amount of data written to SM by CN
Control line T2: Control line for notifying the information of CNT to CTL 1-3: Data line i'' for sending the contents of CNT to OR 4: Data line for sending the contents of SM to OR 'I゛5: Control line for notifying CTL when the transmission of the information in 8M is completed. Control line for instructing PG to generate a character string indicating receivable. R2: For PG. Control line R3: Instructs the PG to generate a character string indicating that reception is not possible. Control line p4: Instructs the PG to generate a character string indicating a transmission request. I) Indicates the start of transmission to the G. Control line 1) 5: Data line for sending the contents of PG to OR R1: Data line R2 for sending the output of ANDl to REG: Output of AN[)2 RM C, data line R3: Control line for C'VL to refer to the contents of RL and G. R4: A control line that notifies that the amount of data instructed by the C6 line has been received from R2.

Claims (1)

[Claims] 1) Two devices that communicate with each other and have data to be transmitted are connected to each other via a data line for transmitting and a data line for receiving a bit string forming an arbitrary bit pattern as data. A device transmits a data transmission request to the other device by sending information indicating the transmission request as a character string consisting of a specific bit pattern via the data line, and the other device transmits the request via the data line. After receiving a character string made up of a specific bit pattern as information indicating acceptance or rejection, if it is accepted, a character string as information indicating the start of the data and the length of the following data. After sending the information, the other device starts sending data (a bit string forming an arbitrary bit pattern) via the data line, and the other device
A two-wire half-duplex system characterized in that even if the received data contains a bit pattern representing a specific character string, it is not recognized as a character string and is received as data. Communication method.