JPH02301228A - Automatic switching control circuit - Google Patents

Abstract

PURPOSE:To adopt a unit for an automatic switching control circuit together with a transmission circuit and to miniaturize a circuit by arranging a changeover switch, a fault detection means and a control means to each of 1st or 2nd termination circuits respectively. CONSTITUTION:First termination circuits 1-4 terminating each of 1st signal paths 11-14 and a 2nd termination circuit 5 terminating a 2nd signal line 15 switched when the 1st termination circuits 1-4 are faulty are provided. Then the 1st or 2nd termination circuits are provided with fault detection means 21-25 detecting the fault of the termination circuits, a changeover switch switching the 1st signal lines 1-4 into the 2nd signal line 15 when the termination circuits are faulty and a control means controlling the changeover switch based on fault information coming from a fault detection means and a subsequent termination circuit and also sending fault information to a host termination circuit are provided. Thus, a unit is adopted for the automatic switching control circuit together with the termination circuit and the circuit is miniaturized, then the addition or revision of an input/output signal line is flexibly coped with.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application 1] The present invention relates to an automatic switching control circuit that switches signal paths when a termination circuit that terminates an input/output signal path has a failure.

[Prior Art] A conventional automatic switching control circuit includes a plurality of fault detection circuits, a control circuit, and a changeover switch that switches input/output signal paths, each of which is connected to a plurality of termination circuits. When a fault occurs in the termination circuit, the fault detection circuit detects this fault and notifies the control circuit of this fault. The control circuit receives this input and controls the changeover switch to switch to a separately determined signal path. In this way, input/output signals are transmitted via this switched signal path. This automatic switching control circuit is centrally arranged and separated from the termination circuit.

[Problems to be Solved by the Invention] The conventional automatic switching control circuit described above is arranged separately from the termination circuit, so when adding an input/output signal path, it is difficult to configure the termination circuit that terminates this input/output signal path. There is a problem in that not only additions but also control circuits and changeover switches in the automatic changeover control circuit must be added and changes accompanying these additions must be made. For this reason, the automatic switching control circuit becomes complicated and cannot be miniaturized, and there are also problems in that it is not possible to respond flexibly to additions or changes of input/output signal paths.

[Means for Solving the Problems] In order to solve such problems, an automatic switching control circuit according to the present invention terminates each of a plurality of first signal paths through which a plurality of input/output signals are transmitted. a plurality of first termination circuits arranged from top to bottom; a second termination circuit that terminates a second signal path that is switched when the first termination circuit becomes a failure; and a first or second termination circuit. a fault detection means in the termination circuit for detecting a fault in the termination circuit; and a fault detection means in the first or second termination circuit for switching from the first signal path to the second signal path in the event of a failure in the termination circuit; control the changeover switch based on the fault information arriving from the fault detection means and the lower end circuit in the first or second termination circuit, and send the fault information to the higher end circuit. and control means.

[Operation] The control means controls the changeover switch based on the fault detection result by the fault detection means and the fault information coming from the lower termination circuit. As a result, the first signal path is switched to the second signal path.

[Example] Next, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the automatic switching control circuit of the present invention. In the same figure, 1 to 5 are terminal circuits, 11 to 1
4 is a signal path (first signal path) through which input/output signals are transmitted;
15 is a signal path (second signal path) through which input/output signals are transmitted when the termination circuits 1 to 5 have a failure, and 21 to 25 are located within the termination circuits 1 to 5, respectively, and detect a failure in the termination circuits 1 to 5. 31 to 35 are located in the termination circuits 1 to 5, respectively, and changeover switch units switch the signal paths 11 to 14 to the signal path 15 when the termination circuits 1 to 5 have a failure; 41 to 44 are respectively located in the termination circuit 1; ~ 5 is a control unit that performs switching control of the changeover switch units 31 to 35 when the termination circuits 1 to 5 fail, and 51 to 55 are failure information (hereinafter referred to as failure signals).
is the signal path through which is transmitted. And signal paths 11 to 14
When a failure occurs in any one of the termination circuits 1 to 4 (first termination circuit) terminating the signal paths 11 to 4 (first termination circuit),
14 is switched to a signal path 15, and this signal path 15 is terminated by a termination circuit 5 (second termination circuit).

Next, FIG. 2 will be explained. This figure is a specific circuit diagram of the termination circuit 2 for explaining the operation of the configuration of the above embodiment. In this figure, parts equivalent to those in FIG. 1 are designated by the same reference numerals, and their explanation will be omitted. In FIG. 2, 101 is a changeover switch that switches the signal path 12 to the signal path 15 under the control of the control unit 42, and 103 and 104 are logic circuits. Further, the signal path 51 is connected to the termination circuit 1, and the signal path 52 is connected to the termination circuit 3. The termination circuit 1 is called an upper termination circuit of the termination circuit 2, and the termination circuit 3 is called a lower termination circuit of the termination circuit 2.

The operation of the automatic switching control circuit configured as described above will be explained. When a fault occurs in the termination circuit 2, the fault detection section 22 detects this and sends this fault signal to the logic circuit 103 and the logic circuit 104. The logic circuit 103 inputs the fault signal from the fault detection section 22 and the fault signal from the signal path 52, calculates the logical sum of these two fault signals, and sends this logical sum output signal to the signal path 52. ,
That is, it is sent to the upper termination circuit.

On the other hand, the logic circuit 104 receives this fault signal and also inverts and inputs the fault signal from the signal path 52, that is, the fault signal from the lower termination circuit. As a result, this logic circuit 104 performs a logical product of these two input signals and sends this logical product output signal, that is, a switch changeover signal to the changeover switch 101. Changeover switch 101
is controlled based on this switch switching signal, and as a result, signal path 12 is switched to signal path 15.

Note that even if the fault signal is input from the fault detection unit 22, the logic circuit 104 inverts the fault signal from the signal path 52 and inputs it, so when the fault signal arrives from the signal path 52, the changeover switch is activated. 101 is not output. Therefore, the selector switch 101 does not operate, and the signal path 12 cannot be switched to the signal path 15. That is, since there is only one signal path 15 that can be switched in the event of a fault, even if a fault occurs in the upper termination circuit, if a fault occurs in the lower termination circuit, the changeover switch in the upper termination circuit will not be activated. If it does not operate and the lower termination circuit becomes a failure, the lower signal path is switched with priority.

Also, when a new termination circuit is added, the termination circuit 1
A terminating circuit having the same configuration as that of 4 to 4 is additionally installed between terminating circuit 4 and 5.

[Effects of the Invention] As is clear from the above explanation, the automatic switching control circuit of the present invention has a changeover switch, a fault detection means, and a control means arranged in each of the first termination circuit and the second termination circuit. Therefore, the automatic switching control circuit is integrated into a unit together with the termination circuit, which has the effect of simplifying the configuration and reducing the size. Further, when adding an input/output signal path, it is only necessary to add this unit, and therefore, there is an effect that the addition or change of the input/output signal path can be flexibly handled.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the automatic switching control circuit of the present invention, and FIG. 2 is a specific circuit diagram of the termination circuit 2 used to explain the operation. 1-5...Terminal circuit, 11-15.51-55...
...Signal path, 21-25...Fault detection section, 31-3
5... Changeover switch section, 41-45... Control section.

Claims (1)

[Scope of Claims] A plurality of first terminating circuits that terminate each of a plurality of first signal paths through which a plurality of input/output signals are transmitted and are arranged from a higher order to a lower order; and the first terminating circuit. a second terminating circuit that terminates a second signal path that is switched when a fault occurs; a fault detection means that is located in the first or second terminating circuit and detects a fault in the terminating circuit; a changeover switch in the first or second termination circuit that switches from the first signal path to the second signal path in the event of a failure in the termination circuit; A fault detection means and a control means for controlling the changeover switch based on fault information arriving from a lower termination circuit and transmitting fault information to a higher termination circuit, the changeover switch, the failure detection means and the control means An automatic switching control circuit characterized in that means is provided in each of the first or second termination circuit.