JPS6398245A - Line control system for communication equipment - Google Patents

Abstract

PURPOSE:To prevent communication from being disabled due to misconnection, by judging whether the terminal of a communication equipment is an input terminal or an output terminal, by retrieving the level of a signal line, and connecting the input terminals and the output terminals of both communication equipments automatically. CONSTITUTION:In a first case, an output Q changes from an H to an L by the leading of a pulse because the D input of a flip-flop circuit 51 is the L. Thereby, switching means 4-1 and 4-4 are turned off, and switching means 4-2 and 4-3 are turned on. Therefore, a third pin in a 25-pin connector for an RS-232-C is connected to a driver 1, in other words, correct connection is performed (continuous line part in 51-Q). Next, in a second case, no change in the output Q is recognized remaining at the H as it is by the leading of the pulse because the D input of the flip-flop circuit 51 is the H. Also, since a line is connected correctly, no switching of terminal switching means is performed (broken line part in 51-Q).

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to a line control system for communication equipment, and relates to a method for automatically controlling a turnout terminal between a data line termination equipment (DCE) and a data terminal equipment (DTE). In particular, it can be used as a communication interface compliant with the R8-232-C standard.

"Prior art and its problems" Conventional communication equipment based on the R8-232-C standard (
When manufacturing equipment using interfaces,
If it is not known whether the equipment to be connected to each other is designed as a DTE, or data terminal equipment, or a DCE, or data line termination equipment, then both parties must connect the signals that correspond to the connector bins. Since they are different, they cannot be connected to each other unless some kind of hardware countermeasure is taken. Specific measures include straight type cables that connect the same bin numbers for DTE-DCE and DTE-D.
Either prepare a cross-type cable in which the bins corresponding to each signal for TE and DCE-DCE are connected, or prepare a switch for switching between DTE and DCE.
Alternatively, it is changed by jumper connections on the printed circuit board. In particular, the communication device of the other party to be connected is D.
If it is unclear whether the communication device is CE or DTE, the hardware of the other party's communication device must be investigated, and the hardware processing must also be performed for each device, which is extremely troublesome.

[Purpose] In view of these conventional drawbacks, it is an object of the present invention to prevent failure of communication due to incorrect connection of the signal line between both communication devices by automatically setting the signal line correctly.

``Summary'' Therefore, in order to achieve its purpose, this invention aims to eliminate unknown signals in the signal lines between communication devices connected to each other.
By selecting this and checking the level of the signal line, it is determined whether the terminal of the communication device is an input terminal or an output terminal, and the input terminal and output terminal of both communication devices are automatically connected. This eliminates the need to change one hardware and also eliminates the need to select the device to be connected.

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

Note that this example uses driver IC751, which is commonly used as an R3-232-C interface.
This will be explained using 88 and receiver IC75189.

In other words, in FIG. 1(a), the communication line is normally in the mark (1) state, so driver 1 and receiver
The communication line between the two is in the space (0) state. In other words, the receiver input terminal is below -3V. Then, as shown in Figure 1 (b), the receiver input terminal and the receiver
If the input end is connected, this line will be in a floating state. Therefore, if a pull-up resistor 11 is attached to the input terminal of the receiver 2 so that the input terminal becomes +3V or more when floating, the logic of the output of the receiver 2 is inverted from the normal state. By detecting this and switching the connection line, normal communication can be performed.

Next, a circuit for automatically setting the signal line will be explained using FIG. 2, taking the transmission and reception lines as an example.

That is, the reference numeral 101 is a first device, for example, a DTE. Further, 102 is a second device connected to the first device, and is, for example, a DCE. And binary data between these devices.

An interface is formed using a 25 pin connector to transfer control and timing signals. Note that this 25-bin connector conforms to the above-mentioned R8-232-C standard, and is also specified in JISC6361. The automatic configuration circuit of FIG. 2 is then applied to that interface. Furthermore, code 1 is a driver for R8-232-C, and 2 is a driver for R8-232.
-C receiver 13 is a signal detecting means, which is generally constituted by an integrated circuit, that is, an IC. A switching means 4 is provided between the first device 101 and the second device 102, that is, a terminal switching device 4-1.4-2 for switching between the input terminal and the output terminal of the first device 101 and the second device 102.
．． 4-3 and 4-4 and circuit switching means 4-5 and 4 for switching one signal line and the signal detection means 3
-6, these switching means are electrically controlled, and in this circuit diagram are set to 5 so that they are turned on by H level input and turned off by L level input. Signal detection means 3 and terminal switching means 4-1 to 4-4
A terminal switching control means 5 for controlling this terminal switching means is provided between them.

This terminal switching control means is a positive edge trigger D.
It is composed of a flip-flop, a flip-flop circuit 51 with clear and preset functions, a one-shot positive pulse generation circuit 52, and a reset circuit 53. Further, the circuit switching control means 8 which controls the circuit switching means 4-5 and 4-6 in conjunction with the terminal switching control means 5 is constituted by a one-shot negative pulse generation circuit. Furthermore, numerals 6 and 7 are inverters.

Further, a pull-up resistor 11 is connected to the input terminal of the signal detection means 3.

"Operation" Next, a method for automatically setting signal lines in the above configuration will be explained using the timing chart of FIG.

First, devices for communication, that is, the first device 101 and the second device 102 are connected, and the power supplies for both are turned on. The reset circuit 53 starts up after all the electronic circuits start up, and its level reaches H at that point, that is, at tl.
It is set so that

Time point 1. In the previous case, the output of the one-shot negative pulse generation circuit 8 is H, so the switching means 4-5 is turned on and the switching means 4-6 is turned off, and the input terminal of the signal detection means 30 is not connected to any line, and Pull-up resistor 11
Since the output of the signal detection means 3 becomes L, the flip-flop circuit 51
The D input of becomes L. At this time, the output of the one-shot positive pulse generation circuit 52 is at L level, so the clock input to the flip-flop circuit 51 is at L level. Further, since the reset circuit 53 is at L level, the output Q of the flip-flop circuit 51 is at H level.

Next, from time t to time t2, the reset circuit 53 goes high, but the output Q of the flip-flop circuit 51 remains high and does not change. Therefore, terminal switching means 4-1, 4-4 are turned on, terminal switching means 4-2 and 4-3 are turned off, and R8-232-
Bin No. 3 of the 25-pin connector for C is connected to the input of the receiver 2. Next, at time t, the one-shot negative pulse generation circuit 8 falls and becomes L level, and the terminal switching means 4-6 is turned on. , 4-5 is off,
Connect the No. 3 pin of the 25-pin connector for R8-232-C to the input end of the signal detection means 3. In this case, there are two possible outputs from the signal detection means 3. That is, in the first case, if the connection line is the receiver 20 input, that line becomes a float and the output of the signal detection means 3 remains at L (solid line portion in FIG. 351-D). In the second case, when the connection line is the output of the driver 1, the line becomes a space state and the output of the detection means 3 becomes H (the broken line part in FIG. 3-51-D).

From time t, the D input of the flip-flop circuit 51 is set, and if a positive pulse is input to CLK of the flip-flop circuit 51, it is triggered by the rising edge of the positive pulse and controls the output Q. Then, time t becomes the rising point of the pulse. As a result, the first case and the second case become as follows.

In the first case, since the D input of the flip-flop circuit 51 is L, the output Q changes from H to L at the rising edge of the pulse. As a result, the switching means 4-1.4-4
is turned off and 4-2.4-3 is turned on. Therefore, the No. 3 pin of the 25-pin connector for R8-232-C is connected to the driver 1, that is, it is correctly connected (solid line section in Fig. 3, 51-Q).

Next, in the second case, since the D input of the flip-flop circuit 51 is H, the output Q becomes H due to the rising edge of the pulse.
It remains unchanged. In addition, since the lines are connected correctly, the terminal switching means does not switch (Fig. 3, 5).
1-Q dashed line part).

Then, the pulse that rises at time t3 falls down at time t4. The one-shot positive pulse generation circuit 52 generates a pulse at this timing.

At time t, the negative pulse of the one-shot negative pulse generation circuit 8 ends, and its level changes from L to H.
become. As a result, the circuit switching means 4-5 is turned on;
-6 is turned off, the communication line is connected from the signal detection means 3 to the communication receiver 2, and the automatic setting is completed.

In the circuit shown in FIG. 2, a flip-flop circuit 51.
It is also possible to replace the one-shot positive pulse generation circuit 52, the reset circuit 53, and the one-shot negative pulse generation circuit 8 with microcomputer software. It becomes even more advantageous. An example of the circuit is shown in FIG. 4, but since the method of testing is substantially the same as that shown in FIG. 2, its explanation will be omitted. Select one unknown signal line from among the signal lines between communication devices and check the level of that signal line to determine whether the terminal of the communication device is an input terminal or an output terminal. However, since the input and output terminals of both communication devices are automatically connected, there is no need to make any hardware changes as in the past, and the effect is that it is possible to communicate with either device. be.

[Brief explanation of the drawing]

FIG. 1 is a basic circuit diagram of a line control system for communication equipment according to the present invention, FIG. 2 is a circuit diagram showing an embodiment, FIG. 3 is a timing chart diagram of FIG. 2, and FIG. FIG. 5 is a circuit diagram showing another embodiment and a functional diagram showing the gist of the present invention. DESCRIPTION OF SYMBOLS 1... Driver, 2... Receiver 13... Signal detection means, 4... Switching means, 5... Terminal switching control means, 6... Inverter, 7... Inverter, 11... ...Pull-up resistor, 101...First device, 102...Second device. Patent applicant Yamani-no-Newel Co., Ltd. Figure 1 (b) Figure 2 Figure 3

Claims (1)

[Claims] a first device; a second device connected to the first device; a signal detection means for detecting the level of a signal line of one of the devices; a terminal switching means for switching between the output terminal and the input terminal of the second device;
a circuit switching means for switching one signal line and the signal detection means, a terminal switching control means for controlling the terminal switching means, and a circuit switching means for controlling the circuit switching means in conjunction with the terminal switching control means, between the devices. circuit switching control means, selects one of the unknown signal terminals in the first or second device, detects the level on the signal line by the signal detection means, and detects the unknown signal terminal in the first or second device; It is determined whether the terminal is an input terminal or an output terminal, and further, the output terminal of the first device and the input terminal of the second device, and the output terminal of the second device and the input terminal of the first device are connected. A line control method for communication equipment characterized by connecting input terminals to each other.