JPH02246561A - Failure detection method between communication devices - Google Patents

Abstract

PURPOSE:To detect not only the trouble of an interface cable, but also the power-off state of a corresponding communication equipment by connecting a specific logic circuit provided to one communication device to the trouble detection part of the other communication device through an interface cable. CONSTITUTION:One communication equipment 1A among communication equipments 1A, 1B is provided with the trouble detection part 4A which has a pull-up resistance 5A at the input part and the other communication equipment 1B is provided with the logic circuit 7B which is connected to the trouble detection part 4A through the signal line 21 in the interface cable 2. The logic circuit 7B is constituted as a logic circuit which enters a high-impedance state by the power-off operation of the communication equipment 1B while generating a low-level output when the power source 6B of the communication equipment 1B is normal. Consequently, not only the trouble of the interface cable 2, but also the power-off state of the corresponding communication equipment can be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a failure detection method between communication devices that perform data communication via an interface cable.

[Prior Art] FIG. 3 is a block diagram for explaining a conventional fault detection method between communication devices.
1B is a communication device, and these communication devices 1A and 1B perform data communication via an interface cable 2.

In addition, each communication device 1A, 1B has one communication control unit 3A, 3B.
, fault detection units 4A, 4B, and power supplies 6A, 6B.

Here, the communication control units 3A and 3B are main units that perform data communication, and these communication control units 3A and 3B are connected via a data bus 20.

Furthermore, the failure detection units 4A and 4B detect cable disconnection (cable failure of the interface cable 2).
The fault detection section 4A of the communication device 1A is connected to the ground section of the communication device 1B via the signal line 21 of the interface cable 2, and the fault detection section 4B of the communication device 1B is connected to the ground section of the communication device 1B via the signal line 22 of the interface cable 2. It is connected to the ground part of the device 1A. In addition, each failure detection unit 4A, 4
Pull-up resistors 5A and 5B are connected near the input section of B.

Further, the power supplies 6A and 6B are for supplying power to various parts of the communication devices 1A and 1B.

Note that a signal ground line 23 is connected between the communication devices 1A and 18.
is interposed. Here, the signal ground line 23 connects the signal return line and reference potential to each communication device! 1A, 1B
This is the ground wire for feeding the

With this configuration, when the interface cable 2 is normal, the failure detection unit 4A in each communication device 1A, 1B
, 4B are input with ground level signals (low level signals) from the corresponding communication devices 1B and 1A, respectively.

However, if a fault occurs in the interface cable 2, such as when the cable is disconnected, the ground level signal will no longer be supplied from the corresponding communication device.

A signal (high level signal) from 5B is input, thereby making it possible to detect the above-mentioned cable fault.

[Problems to be Solved by the Invention] However, in such a conventional failure detection method between communication devices, if the corresponding communication device 1B.

When the power supplies 6B, 6A of 1A are turned off, the ground level signal is input to the failure detection units 4A, 4B in this case as well, so the failure detection units 4A, 4B detect the corresponding communication devices 1B, 4B.
1A is considered normal.

This poses a problem in that a startup operation for starting data communication is performed between the communication devices 1A and 1B.

The present invention was made in view of these problems, and provides a fault detection method between one communication device that can detect not only a fault in an interface cable but also a power-off state in a corresponding communication device. is intended to provide.

[Means to solve the problem] FIG. 1 is a block diagram of the principle of the present invention.

In FIG. 1, 1A and 1B are communication devices, and these communication devices 1A and 1B perform data communication via an interface cable 2. In FIG.

Further, one of the communication devices 1A and 1B is provided with a fault detection section 4A having a pull-up resistor 5A at the input section, and the other communication device 1B
is provided with a logic circuit 7B connected to the fault detection section 4A via a signal line 21 within the interface cable 2.

Here, the logic circuit 7B outputs a low level output when the power supply 6B of the communication device 1B is in a normal state.

It is configured as a logic circuit that enters a high impedance state when the communication device 1B is powered off.

[Work] In the above-described failure detection method between communication devices of the present invention.

If interface cable 2 is normal, communication device 1
A low level signal from the logic circuit 7B of the corresponding communication device 1B (in this case, it is assumed that the power supply 7B of this communication device 1B is normal) is input to the failure detection unit 4B in A.

However, if a failure occurs in the interface cable 2, such as when the cable is disconnected, the logic circuit 7 of the corresponding communication device 1B
Since the low-level signal is no longer supplied from B, the high-level signal from the pull-up resistor 5A is input to the fault detection section 4A, and as a result, the fault detection section 4A is in a state different from that when the interface cable 2 is normal. Detect. As a result, the above cable fault can be detected.

Furthermore, when the power supply 6B of one communication device 1B is turned off, the logic circuit 7B becomes a high impedance state, so a high level signal from the pull-up resistor 5A is input to the failure detection section 4A, which causes the reinterface ace cable 2
Detects a state that is different from the normal state. the result,
The situation is the same as when the cable is disconnected above, and a failure can be detected.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 2 is a block diagram showing an embodiment of the present invention. In FIG. 2, 1A and 1B are communication devices, and these communication devices 1A and 1B are configured to perform data communication via an interface cable 2. However, each communication device 1A
, 1B are communication control units 3A, 3B, failure detection units 4A, 4
B. Power supply 6A.

In addition to 6B, logic circuits 7A and 7B are provided.

Here, the communication control units 3A and 3B are main units that perform data communication, and these communication control units 3A and 3B are connected via a data bus 20.

In addition, failure detection units 4A and 4B detect cable disconnection (cable failure of interface cable 2) or other party's communication equipment! !
1B, LA power supply 6B, 6A is disconnected, and the failure detection unit 4A of the communication device 1A is connected to the logic circuit 7 of the communication device 1B via the signal line 21 of the interface cable 2.
The failure detection unit 4B of the communication device 1B connects to the communication device 1A via the signal line 22 of the interface cable 2.
is connected to the logic circuit 7B. In addition, pull-up resistors 5A, 5 are provided near the input portions of each failure detection unit 4A, 4B.
B is connected.

Here, the logic circuits 7A and 7B are connected to the other party's communication device 1B.
, LA's power supplies 7B and 7A output low level output in normal condition, while the communication equipment on the other side! This is a logic circuit that enters a high impedance state when the 1B and 1A power is cut off.
For this purpose, the logic circuits 7A and 7B are composed of drive elements 71A and 71B with tristate control ends. Note that these logic circuits 7A and 7B are integrated circuits.

With the above configuration, if the interface cable 2 is normal, the failure detection units 4A and 4B in the 1 communication device 1A and 1B
to the logic circuit 7B of the corresponding communication device 1B, 4A (in this case, it is assumed that the power supplies 7B, 7B of the communication device 1B, LA are normal).

A low level signal from 7A is input.

However, if a failure occurs in the interface cable 2, such as when the cable is disconnected, low level signals will no longer be supplied from the logic circuits 7B and 7A of the corresponding communication devices 1B and 1A, so the failure detection units 4A and 4B will not have pull-up signals. resistance 5
High level signals from A and 5B are input, and this causes the failure detection unit 4A.

4B detects a state in which the interface cable 2 is different from the normal state. As a result, the above cable fault can be detected.

Further, when the power supplies 6B and 6A of the communication device 1B and LA are turned off, the logic circuits 7B and 7A are in a high impedance state, so the failure detection unit 4A.

High level signals from pull-up resistors 5A and 5B are input to 4B, which causes the interface cable 2 to
Detects a state that is different from the normal state. the result,
The situation is the same as when the cable is disconnected above, and a failure can be detected.

In this way, it is possible to detect not only a failure in the interface cable but also a power-off state in the corresponding communication device, so even if the power of the communication device 1B or 1A on the other side is turned off, the failure can be detected. Parts 4A and 4B are made by the corresponding Tsushin! ! 1B and 1A are no longer considered to be normal, thereby preventing the communication devices 1A and 1B from starting data communication in this state. As a result, unnecessary data communication activation can be prevented in advance.

Further, since a small-scale circuit such as a drive element with a tri-state control terminal can be used as the logic circuits 7A and 7B, the number of components and circuit scale are not increased, and the structure does not become complicated.

Note that also in this embodiment, the communication device E1A.

A signal ground line 23 is interposed between the terminals 18 as a signal return line and a ground line for supplying a reference potential to each communication device 1A, 1B.

In addition, in principle, either one of the communication devices 1A or 1
B is provided with a failure detection unit 4A or 4B, and the other communication device 1
It is also sufficient to simply provide the logic circuit 7B or 7A at B or 1A.

[Effects of the Invention] As detailed above, according to the fault detection method between communication devices of the present invention, a fault detection section in one communication device is provided in the other communication device via an interface cable. Since a logic circuit is connected that outputs a low-level output when the communication device's power supply is normal and enters a high-impedance state when the communication device's power is turned off, it will not only prevent problems with the interface cable, but also prevent the corresponding communication device from being damaged. It has the advantage that it can also detect power-off conditions.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the principle of the present invention, FIG. 2 is a block diagram showing an embodiment of the present invention, and FIG. 3 is a block diagram showing a conventional example. In fig. 1A and 1B are communication devices, 2 is an interface cable, 3A and 3B are communication control units, 4A and 4B are failure detection units, and 5A and 5B are pull-up resistors. 6A and 6B are power supplies. 7A and 7B are logic circuits. 20 is a data bus, 21 and 22 are signal lines, and 71A and 71B are drive elements with tri-state control ends. 1A 1st - 11 Aishin IEt 2 - 11 Invface Keifure 5A - 7 Lua 77 or - V - 6B ---QL source 7B - One wheel logic circuit 20 --- 7- Tabasu 21 --- 1A, 18 = 2-11 Ink Face Case 5A, 5B - = 7 Luashibu 6A, 6B-112 7A, 7B - Logic circuit 71A, 71st - 1 three-state 1st time 1 faulty dobuia play 20 - 25 bus 21, 22 - signal 1 to 23 - m - signal γ unt° line book 1! Bright bar IFaLflt reservoir 17℃ 1 Figure 1A, 1 day - 2! L interlocking 2-11 Invescale 5A, 5th --- Fuflare Ip7 51-6A, 6B -
II source 20 --- Data bus 21, 22 ---Ippatsu No. 23 --- No. 4) End line conventional 1? Block diagram indicated as l+

Claims (1)

[Scope of Claims] A pair of communication devices (1A, 1B) that perform data communication via an interface cable (2) is provided, and one communication device (1A, 1B) of the pair of communication devices (1A, 1B) is provided.
) is provided with a failure detection unit (4A), and the interface cable (2) is connected to the failure detection unit (4A) in the other communication device (1B) of the pair of communication devices (1A, 1B). A logic circuit (7B) connected via a signal line (21) inside is provided, and the logic circuit (7B) outputs a low level output when the power supply of the communication device (1B) is normal, while the communication device (1B) outputs a low level output. Device (1B)
A failure detection method between communication devices, characterized in that it is configured as a logic circuit that enters a high impedance state when power is cut off.