JPS5829241A - Data communication system - Google Patents

Abstract

PURPOSE:To prevent simultaneous transmission and reception to an opposite station in a data communication system of the half-duplex communication system by detecting data on a transmitting and a receiving line, and then inactivating a receiver or driver by the detection signal. CONSTITUTION:When a signal (b) is inputted to a signal line L2, a receiver 4 convert the input signal to a signal (a), which is inputted to a transmitter and receiver 1 and also inputted to the terminal T of a retriggerable one-shot FF5 at the same time. Then, its output Q' shown by (d) descends, and consequently a driver 3 connected to a signal line L1 is put in a disabled state to inhibiting the transmitter and receiver 1 from transmitting the signal (a) during its reception. While the transmitter and receiver 1 transmits a signal, on the other hand, a retriggerable one-shot FF6 is triggered by the output of the driver 3 to disable the receiver 4 by its output Q', so that the data on the signal line L2 is not inputted to the receiver 1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a data communication system using a dual communication system.

(The first diagram shows transmitter/receiver 0 using the conventional data communication method) (
The circuit diagram for ia (hereinafter referred to as USART) is shown, and the central logic operation i11! + (hereinafter referred to as CPU) converts the transmission data output from parallel to serial, sends a signal to the partner system via the driver 1B + t-, and receives the signal from the partner system via the receiver (4), Convert this to serial/parallel and use CPU! Figure 3 shows the time chart of data communication using the circuit shown in Figure 1, and as shown in Figure 1 (A), the data for Yarakuta in 1 is input to USARTis). υ5
ART (13 to 0 in the same figure indicates that the RxRDYQi number is issued. Therefore, in the conventional example described above, as shown in Fig. If it is not input to USART port 1, this υ!!
AI! Since the RxRDY @ signal was not activated from Tl1), there was a possibility that when data transmission and reception started, systems on both sides via the overvalue line were transmitting and receiving at the same time, leading to a communication failure.

The present invention is based on the above-mentioned points and provides the following, and it is provided in the USART of the end device or the center device! By using the received data itself as a trigger input and disabling reception from the other party during overconfidence, and disabling transmission from the own system during reception, a data overconfidence method is provided that clarifies the transmission and reception timing. Ah, what it is intended to do.

Below, one embodiment of the present invention will be described in detail on the tWA plane.
ai indicates a configuration example of the embodiment of the present invention, and 111 in the figure is CP
Transmission control is performed by U, and (1) is used to convert the parallel data from the CPU (1) into serial data in an appropriate format and output it, or Enter 11i good serial data to parallel data and CPUtt
1K is the USART that outputs the output. (s) is the driver that converts the serial data from the υ5ARTIII to a suitable level, and (4) is the level 0 portion of the received data. Also, Figure 4 shows the time chart of the circuit shown in Figure 3, and according to the time chart of Figure 4 shown below, #! ＄Operation state of the embodiment 1lt-shows 0 If a signal as shown in FIG. 4 comes to the signal line Lm, the level of the input signal is converted by the receiver (4) as shown in the same figure (A) Been US
ARTTl) is input to the 0 and 9 receivers (4
) is input as a tri-force signal to the T terminal of the retrigger pull-in shot flip-flop, and its
The output falls as shown in the figure, the driver (3) is disabled, and the above (this USART II) cannot transmit data while receiving the reconnaissance signal. is transmitting a signal such as the one shown in the figure (Figure 1), and if no data is being received, the signal is converted by the driver iml K into a signal such as the one shown in the Figure - and sent to the destination. At this time, From the output of the driver ts+, the tri-coupled yacht flip-flop (
The trigger input is input to the T terminal of @), and the Q output of this retrigger pull-down switch (@) is also the same figure (:
), and the receiver 14) is disabled, so even if data gets on the self-signal line Ll, that data will not enter USART (1).Thus, according to the present invention, is the Kll that sends and receives data, and priority is given to the system router that started sending data first.
Data transmission and reception will no longer occur at the same tying, and the transmission and reception ties in the dual communication system can be clarified, thereby preventing communication failures caused by defects in the transmission and reception ties. It has the effect of removing

By the way, in the above-mentioned IN3 diagram (embodiment), when a problem such as a runaway software or a circuit disconnection or short circuit occurs in the system at the other end of the communication, overconfidence from the other station is detected in an eight-way manner. In addition to the problem of not being able to recognize the abnormality, there is also the problem of not being able to determine whether the cause is caused by the own station or by the other station. Therefore, when such a failure occurs, it is possible to isolate the cause of the failure in the 8th invention, which is shown in Fig.
1 to (6) are the same as those in the embodiment shown in FIG. It is a switching circuit that closes when the circuit is closed.
Below is this figure 6 time chi? -) The operating state of the circuit will be explained below. Now, in the example circuit of FIG. 5, II
Figure e (assuming that the data is being sent as shown in
Q of retrigger pull shot flip flop (・)
The switching circuit (11) is as shown in the same figure.
The signal line Lst is open and reception is not accepted as in the embodiment shown in FIG. ) is as shown in the same figure (f), and data cannot be sent as described above.Next, if the other party's system is operating normally and the data is not being sent while receiving data, the data cannot be sent. Since the Q of the retrigger pull switch () is "H'", the switching circuit (1) closes the signal line Lv, and the transmission tIi signal output from the USARTisl is transmitted to the driver (3). ), switching circuit 1B), USART via receiver (4)
Return to (1). However, if the other system is malfunctioning and is transmitting data even though it is receiving data, the signal line LIK, which receives this signal, is connected to the ninth retrigger pull button. As shown in the figure, the output of the flip-flop Otub (M1OQ output becomes "Ll" as shown in the figure) and the signal line Lstl- is opened, so the U
The data signal output from SARTO passes through the aforementioned driver (3), switching circuit 18, and receiver (4) circuit and returns to the UIART port, making it easy to determine whether an error has occurred in the local system or the other system. In other words, in the case of the embodiment shown in Figure 0III, whether or not the other system is working normally depends on whether or not the original data is input as is.
Even if there is an abnormality such as no ACK or NAK response from the other system, it is possible to check whether there is an error in the transmission control of the own system, making it easier to find the cause of the abnormality. Since the invention is configured as described above, when attempting to transmit data from multiple systems simultaneously, transmission starts first and priority is given to the 9th system of the 9th system, so that data transmission and reception are the same. The timing of sending and receiving can be clarified without causing communication failures.
In addition to the above-mentioned effects, the ms invention also has the advantage that if a communication failure occurs, the cause of the problem is determined by whether or not the data signal emitted from the ghost is input as is. By distinguishing whether the problem is occurring on the system side or the partner system side, it has the effect of making it easier to respond when an abnormality occurs.

[Brief explanation of drawings]

Figure 1 is a circuit diagram of the conventional example, Figure 8 is a time chart of the same as above, Figure 118 is a circuit diagram of an embodiment according to the first invention of the present invention, Figure 4 is a time chart of the same as above, and Figure 5 is a time chart of the same as above. The circuit diagram and diagram of the embodiment according to the eighth invention are the same time charts as above, and (l) is the transmitter/receiver (USART').

Claims (1)

[Claims] (1) Data communication method K using the zadou communication system
The data transmitted and received by the transmitter/receiver itself is input as input, and the data is controlled so that it is impossible to receive from the other party when transmitting, and to disable transmitting from the own system when receiving. Method 〇Wei (In the data communication method using the Tei dual communication system, the 4th transmission/reception data of the transmitter/receiver is used as a trigger input to make it impossible to receive reception from the other party when transmitting, and to prevent excessive reception from both systems when receiving. If controlled like this, 7-
K. At the time of transmission, whether or not the transmitted data returns to the O transmitter/receiver determines whether the transmission/reception timing of the other system is correct, and in the event of a communication error, it is determined whether the 1iiji6 system is operating normally. An instant communication method 2 that is characterized by being able to isolate the cause of an abnormality by