JPS5946865A - Method for preventing mis-connection of connector cable - Google Patents

Abstract

PURPOSE:To prevent the damage in a transmission circuit that arises in the collision of the outputs of drivers against each other by controlling the enable terminal of a driver gate according to the connection condition of the other connector through a signal transmission cable. CONSTITUTION:When cables are correctly connected, a potential is inputted from a card 1b side to an inverter 7a through a connector 2D, a cable 3 and a connector 2B, and since an inverted output (high level) is supplied to the enable terminal E of a driver 6a, the driver 6a is abled and can transmit a signal toward a receiver 5b in a card 1b. When the connectors 2a and 2d are connected and the connectors 2B and 2C are connected respectively on account of the mis- connection of the cable 3, and attention is paid for the driver 6a on the card 1a side, the potential of a power source VP5 on the card 1b side is supplied through the connector 2C, the cable 3 and the connector 2B to the inverter 7a and therefore the inverted output (low level) is supplied to the enable terminal E of the driver 6a and the driver 6a does not operate.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a driver [! The present invention relates to a method for preventing erroneous connection of a connector cable when signal transmission is performed by reversely connecting a first device and a second device including a jl path and a receiver circuit = t, respectively.

FIG. 1 is a circuit configuration diagram showing an example of a conventional signal transmission circuit. In the same figure, 18 and 1b are respectively mounted with electronic components, electronic bags ff1fff: constituent printed wiring boards (hereinafter simply referred to as cards), 2 to 2D are connectors, 3 are connector cables, 4a, 4bij-
5a and 5b are respective drivers, and 5a and 5b are respective receivers.

In FIG. 1, connector cable 3 connects connectors 2 and 20, and connectors 2B and 21) correctly between cards 1a and 1b, and as a result, from driver 4 to receiver 5a, Also driver 4
A signal is transmitted from the receiver 5a to the receiver 5a.

However, as shown in FIG. 1A, due to incorrect connection of connector cable 3, connector 2A, ! = 2D, and if connectors 2B and 20 are connected, the outputs of driver 4a and driver 4b will not collide with each other.
Circuit damage will occur.

As described above, the conventional signal transmission circuit has the drawback that if a connector cable is incorrectly connected, the circuit may be damaged.

The present invention has been made in order to eliminate the drawbacks of the prior art.Therefore, an object of the present invention is to provide a signal transmission circuit which does not cause circuit damage even if a connector cable is erroneously connected. An object of the present invention is to provide a method for preventing incorrect connection of connector cables.

The key point of the configuration of the present invention is that a driver gate equipped with an enable terminal is used as a driver, and when a connector cable is correctly connected between both cards, a control signal obtained from the other card via the cable is transmitted to the enable terminal. to enable the operation of the driver gate, and when the connector cable is incorrectly connected, the driver gate becomes inoperable depending on the control signal obtained from the mating card via the cable. .

The present invention will now be described in detail with reference to the drawings.

FIG. 2 is a circuit configuration diagram showing an embodiment of the present invention. In this figure, the same or corresponding items as in Figure 1 are labeled with the same ministry names. In addition, 6a,
6btj: Driver gates each equipped with an enable terminal E (gates that operate when the control signal input to the enable terminal E is at a high level, and are inoperative when a control signal is at a low level), 7a and 7b are each equipped with an open collector transistor element. Inverters configured with 111 to 4
indicate the pull-up resistor, Vp5ili, and the voltage of the power supply 11, respectively.

FIG. 2 shows a case where two connectors and 2C and connectors 2B and 2D are correctly connected by the connector cable 3.

Focusing on the driver 6a in the card 1a, the ground potential from the card 1b side is the connector 21), the cable 3,
The inverter 7aVC is input through the connector 2B, and its inverted output () is supplied to the enable terminal EK of the driver 6a, so the driver 6a becomes operational and transmits a signal toward the receiver 5bVc in the card 1bK. Can be done. The same thing can be said about the driver 6bK on the card 1b side.

FIG. 2A shows a circuit configuration when the two connectors and 2D, and the connectors 2B and 2C are connected due to incorrect connection of the connector cable 3 in the circuit of FIG. 2.

In this case, focusing on the driver 6a on the card 1a side,
The potential of the power supply vp 5 on the card 1b side is the connector 2
C, cable 3, inverter 7a via connector 2B
Since the inverted output (low level) is supplied to the enable terminal E of the driver 6a,
Driver 6a does not operate. Driver 6 on card 1b side
The exact same thing can be said about b. As a result, even if the drivers are connected incorrectly, there is no risk of circuit damage.

In the circuit of FIG. 2, if cards 1a and 1b are close together and the ground potential of card 1a is equal to the ground potential of card 1b, there is no problem, but for example, the ground potential of card 1a is higher than that of card 1b. If the voltage is as high as 5V, the enable terminal E of the driver 6b in the card 1b, which would normally be supplied with a high level signal, is supplied with a low level signal and the driver 6b becomes inoperable. An example in which malfunction does not occur even when the ground potentials of both cards are not equal will be described below.

FIG. 3 is a circuit diagram showing another embodiment of the present invention.

In the figure, the same things as in Figures 1 and 2,
Alternatively, corresponding parts are given the same reference numerals. In addition, 8a and 8bU are each a receiver, and 9a and loa are each a driver.

FIG. 3 shows a case where the two connectors 20 and the connectors 2B and 2D are properly connected by the connector cable 3.

Focusing on the driver 6b in the card 1b, the output of the driver 10a in the card 18 is the connector 2A,
The signal is input to the receiver 8b via the cable 3 and the connector 2C, and its output (inopel) is input to the enable terminal E of the driver 10a, so that the driver 6bij becomes operable. Incidentally, the resino<8b is composed of multiple open collector transistor elements, and is configured to generate an output signal of a high level when a signal of a certain level is inputted thereto.

FIG. 3A shows a circuit configuration when the two connectors and 2D and the connectors 2B and 20 are connected due to incorrect connection of the connector cable 3 in the circuit of FIG. 3.

In this case, focusing on the driver 6b on the card 1b side,
Since no signal is input to the receiver 8b from the card 1a side, the low level output of the receiver 8b is not supplied to the enable terminal E, and the driver 6bl- is not operated. In this case, driver enable control is performed only on the card 1b side and not on the card 1a side, but when the input of the enable terminal becomes low level, the output impedance of the driver element becomes high, so the circuit No damage will occur.

In the embodiment shown in FIG. 3, enable control is performed using the other card's ground potential (and the other card's driver output), so the distance between the transmitter and receiver 11 is long; Even if there is a difference in ground potential between the two countries, it will not be affected by the difference (it can prevent incorrect connection of the connector couple).

According to this invention, the enable terminal of the driver cable is controlled by the connection state of the connector on the other side via the signal transmission pull. In the impedance state, it is possible to prevent damage to the transmission circuit that conventionally occurs due to the outputs of the drivers colliding with each other.

The present invention can also be applied to general transmission circuits that form signal transmission paths using connector cables.

[Brief explanation of drawings]

Figure 1 does not show a conventional signal transmission circuit (1 configuration diagram, 1A
The figure is a configuration diagram showing the circuit configuration when the connector cable is incorrectly connected in the signal transmission circuit of Figure 1, Figure 2 is a circuit configuration diagram showing one embodiment of the present invention, and Figure 2A is the
Figure 3 is a circuit diagram showing another embodiment of the present invention, and Figure 3A is a diagram showing the circuit configuration when an incorrect connection is made in the circuit shown in Figure 3. FIG. Code explanation 1a, 1b...Card, 2A-2D...
・ Connector, connector, 3... Connector cable, 4
a, 4b...driver, 5a, 5b...
・Receiver, 6a, 6b...Driver, 7a,
7b...Inverter, 3a, 8b...
Receiver, 9a, 10a...Driver's agent Patent attorney Akio Namiki Agent Patent attorney Kiyoshi Matsuzaki Figure 1 Figure JA

Claims (1)

[Claims] 1) In a signal transmission circuit in which a first device and a second device each including a driver circuit and a receiver circuit are connected in reverse by a connector cable to transmit a signal from the driver circuit to the receiver circuit, the driver circuit When the connector cable is correctly connected between the first device and the second device, a control signal obtained from the other device via the cable is transmitted to the enable terminal. When the connector cable is incorrectly connected, supplying a control signal obtained from the other device via the cable to the enable terminal will make the driver gate inoperable. A method for preventing incorrect connection of connector cables.