JPH0815280B2 - Abnormality monitoring device for multi-CPU system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to an apparatus for monitoring an abnormality in a transmission function of a multi-CPU system.

B. SUMMARY OF THE INVENTION The present invention is an apparatus for outputting data for transmission function diagnosis from each unit of a multi-CPU system at a constant cycle to a system bus, and checking whether or not there is an abnormality based on the data received back. By monitoring the level of the input signal of one unit that has returned from another unit and regulating the switching unit so that when the level drops, the switching is controlled so that internal folding occurs in the other unit. This prevents repeated switching operations of the switching unit when the power is turned off.

C. Conventional technology In a multi-CPU system that uses a half-duplex transmission path as the system bus, diagnostic data is output from the CPU units to the system bus at fixed intervals to diagnose the transmission function. It is received back to check if there is an abnormality in the transmission function. If there is an abnormality, disconnect the unit that received the data from the system bus, return the diagnostic data in the unit, and check the data by sending and receiving. At this time, if the unit is normal, reconnect the unit to the system bus. Connect to.

Fig. 2 shows such a system. U _{1 to} U ₃ are CPUs.
(Central processing unit) A unit, which is connected to the system bus SB in a multiple manner. 1 ₁ to 1 ₃ CPU, 2 ₁ to 2 ₃ transmission unit, CB ₁ to CB ₃ is a CPU bus. The units U ₂ , U ₃ , the transmitter 3A, the receiver 3B, and the system bus SB constitute _one unit Y, and the unit U ₁ is installed at a position distant from the unit Y. The unit U ₁ and the device Y are connected to each other by a 4-wire full-duplex transmission line composed of an optical communication line, and the full-duplex transmission line is a 2-wire half-duplex on the device Y side. It is converted to a transmission line and coupled to the system bus SB. 4A and 4B are a transmitter and a receiver,
E / 0, 0 / E, etc. are used as the transmitters 3A, 4A and the receivers 3B, 4B, respectively. 5 is a switching unit, and a function of switching between the transmitting unit 2 ₁ of sender and receiver of the transmission unit 2 ₁ connects the system bus SB.

D. Problems to be Solved by the Invention When the unit U ₁ and the device Y are separated from each other as in the example of FIG. 2, the following problems occur because the power supplies are separate. That is, when outputting the data for diagnosis from Yunitsuto U ₁ to turn off the power of the device Y, it becomes impossible aliasing of the signal in the device Y, transmitting unit 2 ₁ is the same recognition abnormal transmission function, As a result, the switching unit 5 repeats the switching operation. Thus, although the transmission function is not abnormal, the switching unit 5
It is not preferable for the system to perform the abnormal operation of. An object of the present invention is to prevent abnormal operation of the switching unit when the power of the device Y is cut off.

E. Means for Solving Problems The present invention monitors the level of an input signal from another unit when sending diagnostic data to the other unit, and switches when the level drops. The control unit is provided with a control unit that regulates the transmission function diagnostic data so that the data is internally folded.

F. Function When a signal for transmission function diagnosis is sent from the transmission unit of one unit to another unit through the system bus, the signal will not be returned if the power of the other unit is turned off. At this time, since the level of the input signal of one unit is lowered, the switching unit is regulated so as to be internally folded.

G. Embodiment FIG. 1 is a view showing an embodiment of the present invention, in which the same symbols as in FIG. 2 indicate the same parts. In this embodiment, the restricting portion 6 is provided on one of Yunitsuto U _1, the restricting portion 6, sends the data for transmission function diagnosis apparatus Y (see FIG. 2) from the transmission unit 2 ₁ of Yunitsuto U ₁ At this time, the level of the input signal of the receiver 4B is monitored, and when the level is lowered, the switching unit 5 is regulated to a state in which the diagnostic data is internally folded. Has the function of outputting.

Next, the operation of the above embodiment will be described. For example, a serial data for periodically transmitted function diagnosis from the transmission unit 2 ₁ is output, the data is sent to the transmitter 4A, through the receiver 3B and the system bus SB for example Yunitsuto U ₂ (see FIG. 2) And then returned from here to the system bus SB, oscillator 3A,
Receiver 4B and through the switching unit 5 returns to the transmission unit 2 _1. If the returned data matches the output data, the abnormal check of the transmission function ends, but if one bit of the data is recognized to be different from the output, for example, the transmission unit 2 ₁ Based on the switching command, the switching unit 5 is switched so that the contents of the data are folded back. And performs a checking of the reception by the internal loopback, the transmission side of the transmission unit 2 ₁ again by the switching unit 5 is connected to the device Y if it is considered healthy. If where power of the device Y is turned off, even if the data for diagnosis is issued from the transmission unit 2 _1, data input to the receiver 4B is the level of the input signal decreases over the entire bits Therefore, the regulation unit 6 issues a regulation command to the switching unit 5, and as a result, the switching unit 5 is regulated in a state in which the data is internally folded. After that, this state is maintained and the switching operation is not repeated. The input signal level drop is not an abnormality of the system bus, but another unit is
Since it is the same as the state of being separated from the above, the above-mentioned operation does not affect the abnormal check of the transmission function.

H. Effects of the Invention As described above, according to the present invention, when the level of the input signal of one unit is lowered, the internal folded state of the data is forcibly held. When the power of the device including the other units connected to one unit is turned off, it is possible to prevent an inconvenient state such as the repeated switching operation, and to not affect the abnormal check of the transmission function.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram showing a conventional example. 1 ₁ to 1 ₃ ... CPU, 2 ₁ to 2 ₃ ... transmission unit, 3A, 4A ... transmitter,
3B, 4B ... Receiver, 5 ... Switching section, 6 ... Regulator section.

Claims (1)

[Claims] 1. A device for monitoring an abnormality of a multi-CPU system in which a plurality of units including a CPU and a transmission unit are multiple-connected to a system bus, wherein data for transmission function diagnosis is transmitted from a transmission unit of one unit to a system bus. Sent to another unit via the transmission unit, and the data returned here is received by the transmission unit of the one unit to check whether there is an abnormality in the transmission function. In an abnormality monitoring device that disconnects the transmission unit from the system bus and connects the transmission side to the reception side so that the diagnostic data is folded back internally, when the diagnostic data is sent to another unit, the other The level of the input signal that is returned from the unit and input to one unit is monitored, and when the level drops, the switching unit is activated and the diagnostic data is internally folded. Abnormality monitoring device having a multi-CPU system, characterized in that a regulating portion for regulating a state such that return.