JPH0498950A - Signal transmission system - Google Patents

Abstract

PURPOSE:To detect a specific driver circuit to be driven by providing a pull- down resistor having a resistance to specify its own circuit, a daisy chain connection switching means and its control means to the system. CONSTITUTION:When a fault is detected by a control circuit 2-l of a driver circuit 1-1, the control circuit 2-1 turns on a switch circuit 3-1 and informs a fault to a CPU 6 of a receiver circuit 4 through a daisy chain connection signal line 101. The CPU 6 outputs an inhibit signal to all control circuits 2-i so that all switch circuit other than a switch circuit of the driver circuit in which a fault is detected are not closed. Then a potential V1 at a connection point between the signal line 100 and the other end of a register R0 is expressed as V1=(R0/R1+R0).Vcc. That is, when the potential V1 is expressed as Vi=(R0/ Ri+R0).Vcc, it is discriminated that the driver circuit 1-i is driven.

Description

TECHNICAL FIELD The present invention relates to a signal transmission system, and more particularly to a signal transmission system in which output signals from a plurality of driver circuits are wire-ORed via daisy-chained signal lines and input to a receiver circuit.

Prior Art Conventionally, in this type of signal transmission system, a switch circuit of each of a plurality of driver circuits is provided with, for example, an oven collector output TTL (transistor-tr
Ansistor logic) circuits are used, and the output signals from these driver circuits are wire-ORed via daisy-chained signal lines and input to a receiver circuit.

In such a conventional signal transmission system, the output circuit of each of the multiple driver circuits is composed of a switch circuit, so when wired-OR is performed via a daisy chain connected signal line, all the outputs of the driver circuits are Since it is possible to determine only two states, ie, whether the switch circuit is off or not, there is a drawback that the specific driver circuit driven cannot be detected.

OBJECTS OF THE INVENTION The present invention has been made in order to eliminate the above-mentioned drawbacks of the conventional system, and it is an object of the present invention to provide a signal transmission system capable of detecting a specific driver circuit driven.

Configuration of the Invention A signal transmission system according to the present invention is a signal transmission system in which output signals from a plurality of driver circuits each connected in a daisy chain by a first signal line are inputted to a receiver circuit via the first signal line. a second signal line connecting the plurality of driver circuits in a daisy chain;
a plurality of pull-up resistors provided in each of the plurality of driver circuits, each having a resistance value for specifying its own circuit; and a plurality of pull-up resistors provided in each of the plurality of driver circuits, the pull-up resistor and the second a plurality of switching means for turning on and off connections with the signal line; and a plurality of controls provided in each of the plurality of driver circuits and controlling the connection of the switching means in response to a specific signal output to the first signal line. and a discriminating means for discriminating the driver circuit that has sent out the specific signal in accordance with the voltage value input via the second signal line.

Embodiment Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention. In the figure, a plurality of driver circuits 1-i (i =
1.2. . . . -, n) and the receiver circuit 4 are connected to the signal line 100. connected in a daisy chain by lots.

The driver circuits 1-i each have a control circuit 2-1 connected to the signal line 1ull, and one end connected to a pull-up power supply (■.C).
and a switch circuit 3-1 whose other end is connected to the signal line 100 via a pull-up resistor Rj, each having a resistance value for specifying its own circuit, that is, each of which is assigned a different resistance value. is provided.

The receiver circuit 4 has a potential V1 at the connection point between the signal line 100 and the other end of the resistor RO whose one end is grounded.
/D (Analog/Digital) conversion circuit 5, CPU (Central Processing Unit) 6, which performs determination processing to determine which driver circuit 1-i has generated an abnormality and has sent a failure report, and output. A terminal 7 is provided on both sides.

The operation of one embodiment of the present invention will be explained using FIG.

When an abnormality is detected by the control circuit 2-1 of the driver circuit 1-1, the control circuit 2-1 turns on the switch circuit 3-i and turns on the signal line 10 of the daisy chain connection.
1 to notify the CPU 6 of the receiver circuit 4 of the abnormality.

Upon receiving the abnormality notification from the control circuit 2-1, the CPU 6 switches all the switch circuits (here, switch circuits 3-2 to 3-3) except the switch circuit of the driver circuit in which the abnormality has been detected (here, switch circuit 3-1). -n) is outputted to all the control circuits 2-i to prevent them from turning on.

As a result, switch circuit 3-1 of driver circuits 1 to I
switch circuits 3-2 to B-n of the other driver circuits 1-2 to 1-n remain off.

Therefore, the potential V1 at the connection point between the signal line 100 and the other end of the resistor RO is Vl=(RO/R1+RO)·Vcc.

Even when an abnormality is detected by the control circuit 2-2 of the driver circuit 1-2, only the switch circuit 3-2 of the driver circuit 1-2 is turned on, similar to the operation described above, and the other driver circuits 1-2 are turned on. -1.1-3 to 1-n switch circuit 3
-1. Since 3-3 to 3-n remain off, the potential v1 is Vl =, (RO/R2+RO) 'Vcc
becomes.

Further, even when an abnormality is detected by the control circuit 2-n of the driver circuit 1-n, only the switch circuit 3-n of the driver circuit 1-n is turned on, similar to the operation described above, and the other drivers Since the switch circuits 3-1 to 3-(n-1) of circuits 1-1 to 1-(n-1) remain off,
The potential v1 is Vl-(RO/Rn+RO)'Vo.

becomes.

The A/D conversion circuit 5 A/D converts the potential vl and sends it to the CPU 6.
Therefore, the CPU 6 can specify the driver circuit 1-i based on the value from the A/D conversion circuit 5.

Sunawachi, the potential Vl is Vi - (RO/Ri +RO)
- When the voltage is VCC, it can be determined that the driver circuit 1-i is driving.

In this way, each driver circuit 1-i connected in a daisy chain by the signal lines 100 and 101 is provided with a pull-up resistor R1 having a resistance value for specifying its own circuit, and one end connected to the pull-up power supply (Vcc). A switch circuit 3-i is connected to the switch circuit 3-i, the other end of which is connected to the signal line 100 via a pull-up resistor Ri, and a switch circuit 3-i that is
A control circuit 2-i is provided to control the connection of the driver circuit 2-i, and when an abnormality is detected in the control circuit 2-1 of the driver circuit 1-1, the potential V1 which is A/D converted by the A/D conversion circuit 5 is provided. By having the CPU 6 determine the driver circuit 1-i that outputs the failure report according to the value of , it is possible to detect the specific driver circuit 1-j that has been driven.

For example, since it is possible to specify which device has become abnormal in a computer system, maintenance and replacement time for the system can be significantly reduced.

DETAILED DESCRIPTION OF THE INVENTION According to the present invention, each of the plurality of driver circuits includes a pull-up resistor having a resistance value for specifying its own circuit, and a signal connected to the pull-up resistor in a daisy chain. A switching means for turning on and off the connection to the line, and a control means for controlling the connection of the switching means according to the fault report output, are provided, and the fault report is made according to the voltage value inputted through the signal line. By determining the driver circuit that has sent out the signal, it is possible to detect the specific driver circuit that has driven the signal.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the configuration of an embodiment of the present invention. Explanation of symbols of main parts 1-1 to 1-n...Driver circuit 2-1 to 2-
n...Control circuit 3-1 to 3-n...Switch circuit 5...
・A/D conversion circuit 6...CPU

Claims (1)

[Claims] (1) A signal transmission system that inputs output signals from a plurality of driver circuits each connected in a daisy chain by a first signal line to a receiver circuit via the first signal line, the plurality of driver circuits a second signal line for daisy chain connection of the plurality of driver circuits, a plurality of pull-up resistors provided in each of the plurality of driver circuits and each having a resistance value for specifying its own circuit, and a plurality of pull-up resistors provided in each of the plurality of driver circuits. and a plurality of switching means for turning on and off the connection between the pull-up resistor and the second signal line, and a plurality of switching means provided in each of the plurality of driver circuits, according to a specific signal output to the first signal line. It is characterized by comprising a plurality of control means for controlling the connection of the switching means, and a discrimination means for discriminating the driver circuit that has sent out the specific signal according to a voltage value inputted through the second signal line. signal transmission system.