JPH01193953A - System for detecting abnormality of bus - Google Patents

Abstract

PURPOSE:To discriminate the place of an insulation failure by outputting an abnormality signal when a voltage which occurs at the time of driving a bus is larger than a prescribed voltage. CONSTITUTION:Data is transmitted in the bus 331 by setting a switching transistor 311 to an on state or off state. A comparator 221 detects the potential of the bus 331 when the switching transistor 311 is switched from the on state to the off state. When the potential becomes higher than a prescribed one (7V, for example), a signal 1 is outputted from the comparator 221. An alarm device 223 gives an alarm in correspondence with the signal 1 outputted from the comparator 221. Consequently, that the insulation failure has occurred in the bus 331 can be discriminated when a transient potential which occurs at the time of switching the switching transistor 311 from the on state to the off state is larger than the prescribed potential.

Description

[Detailed Description of the Invention] [Summary] Regarding a bus abnormality detection method in a device that inputs and outputs signals via a bus, a drive means for driving the bus and a drive means are provided for the purpose of determining the location of insulation failure. and voltage comparison means that outputs an abnormal signal when the voltage generated when driving the bus is larger than a predetermined voltage.

[Industrial application field]

The present invention relates to a bus abnormality detection method, and more particularly to a bus abnormality detection method in a device that inputs and outputs signals via a bus.

Note that in this specification, a bus that connects a plurality of input/output devices, and output pins of drivers and input pins of receivers of each input/output device are collectively referred to as a "bus."

[Conventional technology]

Normally, in a device that inputs and outputs signals via a bus, if a failure such as a disconnection occurs in the bus, the signal transfer will not be performed normally, so the abnormality can be discovered in the CPU or the like.

For example, as shown in FIG. 6(a), a CPU 621, an input/output device a 631, and an input/output device b6 are connected via a bus 611.
Consider the case where 41 is connected.

Here, CPtJ621 and input/output device a631 are connected to bus 6.
11, and the input/output device b641 is connected near the other end.

FIG. 6(b) shows how the CPU 621 drives the bus 611.

Termination resistors are connected to both ends of the bus 611. Further, the CPU 621 includes a switching transistor 623 for bus drive, and the collector side of the switching transistor 623 is connected to the bus 611.
The emitter side is grounded. Bus 6 from CPU621
When transmitting data "1" to the transistor 11, the switching transistor 623 is turned off. At this time, the collector side potential of the switching transistor 623 becomes a predetermined potential (usually 3 to 4 V) determined by the ratio of the terminating resistors. Also,
When transmitting data “0°” from the CPU 621, the switching transistor 623 is turned on. At this time, the bus 611 is connected to the switching transistor 623.
It is grounded via.

[Problems to be Solved by the Invention] By the way, in the conventional method described above, if a part of the lotus 611 becomes insulated, there are input/output devices that receive data normally and other input/output devices that do not receive data normally. In order to
Although it is possible to detect that some kind of failure has occurred in the device as a whole, there is a problem in that it is difficult to determine whether it is an abnormality in the bus or in the input/output equipment.

For example, when an insulation failure occurs near the input/output device b641 (the positive potential (+5V) side of the power supply and the bus 611 are connected isometrically with a resistor with a resistance value of 1Ω, for example),
The data sent from the CPU 621 is changed from "°1" to "°"0.
When the switching transistor 62
6), the voltage on the bus 611 near the input/output device a 631 changes as shown in FIG. 6(c). Further, the voltage on the bus 611 near the input/output device b641 changes as shown in FIG. 6(d).

The actual bus 611 has a certain impedance, and transient voltage fluctuations occur due to reflection.

Therefore, as shown in FIG. 6(c), the input/output device a63
1 can receive the data “0°” output from the CPU621, and the input/output device b641 can receive the data “0°” output from the CPU621.
The data ``0'' output from 21 cannot be received, and the cause of the failure is unclear.

The present invention was created in view of these points, and an object of the present invention is to provide a lotus abnormality detection method that can determine the location of insulation failure.

[Means to solve the problem]

FIG. 1 is a principle block diagram of the bus abnormality detection method of the present invention.

In the figure, drive means 111 drives bus 131.

The voltage comparison means 121 outputs an abnormal signal when the voltage generated when the drive means 111 drives the bus 131 is higher than a predetermined voltage.

Therefore, the overall configuration is such that an abnormal signal is output when the voltage generated when driving the bus 131 is higher than a predetermined voltage.

(Operation) The bus 131 is driven by the drive means 111, and the voltage generated at that time is introduced into the voltage comparison means 121.The voltage comparison means 121 compares the introduced voltage with a predetermined voltage, An abnormal signal is output when the voltage is higher than a predetermined voltage.

In the present invention, by outputting an abnormal signal when the voltage generated when driving the bus 131 is higher than a predetermined voltage, it is possible to determine the location of the insulation failure.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 2 shows the overall configuration of an embodiment to which the bus abnormality detection method of the present invention is applied. Further, FIG. 3 shows a detailed configuration of an embodiment to which the bus abnormality detection method of the present invention is applied.

(2) Correspondence between the embodiment and FIG. 1 Here, the correspondence between the embodiment of the present invention and FIG. 1 will be shown.

The drive means 111 includes the switching transistor 31
Corresponds to 1.

Voltage comparison means 121 corresponds to comparator 221.

Bus 131 corresponds to bus 331.

Examples of the present invention will be described below assuming that the correspondence relationship as described above exists.

2. Configuration of the Embodiment In FIG. 2, a device to which the bus abnormality detection method of the present invention is applied, such as a computer system, includes a CPU 210 that performs overall control and calculations, and a memory that stores data and programs that the CPU 210 directly reads and writes. 241 and
A disk device 263 and a disk device 26 for holding data and programs to be processed by the CPU 210.
3, a keyboard 273 for inputting data, a display 275 for displaying data, an I10 adapter 271 for controlling the keyboard 273 and display 275, and a keyboard 273 for inputting data, A direct memory access control unit (hereinafter referred to as D) for performing input/output without going through the CPU 210.
(referred to as MAC) 251.

The computer system also includes a comparator 221 that compares voltage values to detect a bus abnormality, and an alarm device 223 that issues an alarm according to the comparison result of the comparator 221.

In addition, the CPU 210. Memory 241. The DMAC 251 is housed in the control board 200, and this control board 2
00 is equipped with a set of comparators 221 and an alarm device 223. Similarly, other input/output devices (I10 adapter 261
, 271) is also provided with a set of comparators and an alarm device (not shown).

CPU210. Memory 241. DMAC251゜I10
The adapters 261, 271 and the comparator 221 are connected to the bus 23
Connected to 1. The I10 adapter 261 and the disk device 263 are connected.

The I10 adapter 271 and the keyboard 273 are connected, and the I10 adapter 271 and the display 275 are connected.

FIG. 3 shows the detailed configuration of one bus 331 among the (plurality of) connection lines constituting the bus 231.

In the figure, terminating resistors are connected to both ends of a bus 331. One end of bus 331 (hereinafter referred to as end A)
is a 250Ω resistor 381 and a 580Ω resistor 38.
3 is connected to the other end of the resistor 381, and the operating voltage 5 is connected to the other end of the resistor 381.
(2) is applied, and the other end of the resistor 383 is grounded. Similarly, a 250Ω resistor 385 and a 580Ω resistor 3 are connected to the other end of the bus 331 (hereinafter referred to as the B end).
87 is connected to the resistor 387, and the operating voltage 5 is applied to the other end of the resistor 385, and the other end of the resistor 387 is grounded.

Further, the CPU 210 includes a switching transistor 311 for driving the lotus 331. The collector side of the switching transistor 311 is connected to the bus 331, and the emitter side is grounded.

Further, the non-inverting input terminal of the comparator 221 is connected to the bus 331, and the inverting input terminal of the comparator 221 is connected to a predetermined voltage (e.g. 7cm), which divides the operating voltage (resistor 381
(determined based on the voltage divided by the resistor 383) is applied. The output of comparator 221 is input to alarm device 223.

In addition, in FIG. 3, other components connected to the bus 331 are omitted.

1-Made by Okudanki ShikameNext, the operation of the bus abnormality detection method according to the embodiment of the present invention described above will be explained.

FIG. 4 shows how to calculate the generated voltage when an insulation failure occurs in the bus 331. Further, FIG. 5 shows the state of voltage change that occurs transiently when the switching transistor 311 is switched from an on state to an off state.

Now, there is a CPU 210° comparator 2 near the A end of the bus 331.
21 is connected to the I10 adapter 271 near the B end, and there is an insulation failure near the B end (the 5■ line where the bus 331 supplies the operating voltage 5■ through the 1Ω resistor 391 isometrically). Consider the case where a state in which the

(i) Calculation of generated voltage ■ Voltage of bus 331 when switching transistor 311 is in steady state: When the vicinity of the B end of lotus 331 is connected to line 5 through resistor 391, as shown in Fig. 4 (a) Bus 3 as shown in
31 is connected to line 5 through a parallel circuit consisting of resistors 381, 385°391, and resistor 38.
It is grounded through a parallel circuit consisting of 3.387.

Here, the switching transistor 311 is in the on state (
(assuming 200mA current), the potential at terminal A is 0, B
If the potential at the end is 8 (see Figure 4 (b)), then V,/290+0.2=(5-VA)/1,',v
, -v, 嬌4,8■... (1). Similarly,
A when the switching transistor 311 is in the off state
The terminal potential v and the B terminal potential ■8 (see Figure 4 (c)) are V, = V, = 290/(290+1)X5#5V...
...(2) becomes.

■Voltage of the reflected wave when the switching transistor 311 is switched from the on state to the off state: When the switching transistor 311 is switched from the on state to the off state, the current flowing into the A terminal via the bus 311 is IA
Then, the potential ■ at the A end can be expressed as VA =Vs -ZoxlA' - (3).

When the switching transistor 311 is on, V
A = 4.8V, IA #0.2A, and by substituting these values into equation (3), we obtain Vs""24.8V... (4) (usually used as a signal line) The impedance of the wire used is 10
Since it is around 0Ω, zo=t.

(calculated as OΩ).

Therefore, equation (3) becomes VA = 24.8-100XIA (5).

Moreover, since the current IA flows into the ground via the resistor 383, it becomes (5-VA)/250+I=VA1580 (6).

From equations (5) and (6), VA#17V... Obtain (7).

Therefore, when the switching transistor 311 is switched from the on state to the off state, the potential at the A terminal becomes 17V until the reflected wave returns.

FIG. 5 shows the collector side potential of the switching transistor 311. Since the A end of the bus 331 and the collector side position of the switching transistor 311 are almost the same,
The collector side potential of the switching transistor 311 is initially 17V (from equation (7)). Furthermore, the collector side potential of the switching transistor 311 approaches 5V (from equation (2)) in the steady off state with time.

(ii) Abnormality Detection Next, the operation for detecting insulation failure of the switching transistor 311 based on the reflected wave determined above will be described.

When the switching transistor 311 is switched from the on state to the off state, the potential at the A terminal becomes 17V until the reflected wave returns.

Since the non-inverting input terminal of the comparator 221 is connected to the vicinity of the A terminal of the bus 331, the comparator 221 performs a voltage comparison operation according to the potential of the A terminal.

When the potential at the non-inverting input terminal reaches 17V, which is higher than the potential 7■ at the inverting input terminal, the comparator 221 supplies a signal "1" to the alarm device 223. In the alarm device 223, the comparator 221
In response to the signal "1" supplied from the bus 331, the bus 331 notifies an external operator that an insulation failure has occurred in a part of the bus 331 by sounding an internal buzzer or lighting a warning light.

Note that if the line length of the switching transistor 311 is long, the time it takes for the reflected wave to return will be proportionally longer. For example, if the line length of the bus 331 is 10 m, the time it takes for the reflected wave to return when the switching transistor 311 is switched from the on state to the off state is 100 m.
It will be about ns.

Therefore, it is necessary to use a comparator 221 that can perform voltage comparison within 100 ns.

(2) Summary of Implementation J By turning the switching transistor 311 on or off, the bus 331 is driven (data is sent). Further, the comparator 221 detects the potential of the lotus 331 when the switching transistor 311 is switched from the on state to the off state, and when the potential becomes higher than a predetermined potential (for example, 7V), the comparator 221 detects the potential of the lotus 331 when the switching transistor 311 is switched from the on state to the off state.
21 outputs a signal "'1".The alarm device 223 is
A warning (
(buzzer, warning light, etc.).

Therefore, when the voltage (potential) generated when the switching transistor 311 is switched from the on state to the off state is larger than a predetermined voltage (potential), it can be determined that an insulation failure has occurred in the bus 331.

(2) Modified embodiment of the invention In the embodiment of the invention described above, the comparator 22
In response to the signal "1" output from the comparator 221, a warning is issued to notify an external operator of insulation failure.
Q, and the CPU 210 may take countermeasures.

Further, in the embodiment, the switching operation of the switching transistor 311 in the CPU 210 was considered, but the same can be considered when the drivers in other components operate. At this time, the comparator provided in each keyboard performs a voltage comparison operation, and furthermore, any alarm device (
Insulation failure of the bus 331 can be determined based on warnings from a plurality of warnings.

Furthermore, in ``Correspondence between Examples and Figure 1'',
Although the correspondence between the present invention and the embodiments has been described, those skilled in the art will easily assume that the present invention is not limited to this and that there are various modifications.

〔Effect of the invention〕

As described above, according to the present invention, the location of insulation failure can be determined by outputting an abnormal signal when the voltage generated when driving the bus is higher than a predetermined voltage, which is extremely useful in practice. It is.

[Brief explanation of the drawing]

FIG. 1 is a principle block diagram of the bus abnormality detection method of the present invention, FIG. 2 is an overall configuration diagram of an embodiment to which the bus abnormality detection method of the present invention is applied, and FIG. 3 is a block diagram of the bus abnormality detection method of the present invention. FIG. 4 is an explanatory diagram of the calculation of the generated voltage in the embodiment, FIG. 5 is an explanatory diagram of the generated voltage in the embodiment, and FIG. 6 is an explanatory diagram of the conventional example. In the figure, 111 is a drive means, 121 is a voltage comparison means, 131 is a bus, 200 is a control board, 210 is a CPU, 221 is a comparator, 223 is an alarm device, 231.331 is a bus, 241 is a memory, 251 is a DMAC . 261.271 is an I10 adapter, 263 is a disk device, 273 is a keyboard, 275 is a display, 311 is a switching transistor, and 381.383, 385, 387, and 391 are resistors. Book % BIEI (71 厘空aro,..., ri ■Fig.

Claims (1)

[Claims] (1) Drive means (111) for driving the bus (131)
), and the bus (131) by the drive means (111).
A bus abnormality detection method comprising: voltage comparison means (121) that outputs an abnormal signal when a voltage generated when driving is larger than a predetermined voltage.