JPS5825286B2 - input/output device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an input/output device, and particularly to an input/output device suitable for use in process input/output in a computer system.

In a computer control system that includes terminal cards for connection to a plurality of plants via an input/output control device, a failure of one card may cause malfunction of the entire system.

FIG. 1 shows a block diagram of a standard digital input/output device in a conventional computer control system, in which 1 is a CPU, 2 is a digital input control device, 3 is an address line, 4 is a data line, 5 is a is an error line, 6 is a matching circuit, 7 is a gate, 8 and 11 are level converters, 9 is an external contact, 10 is a fuse, 12 is a fault output gate, 1
3 indicates power supply lines.

In this configuration, the digital input control device 2 sends an address to the address line 3 in response to a command from the CPU 1.

A voltage is applied to the external contact 9 from a power line 13 through a fuse 10, and the state of the contact 9 is converted to an internal level by a level converter 8.

When the matching circuit 6 is selected according to the contents of the address line 3, it opens the gate 7 and sends data to the data line 4, and the digital input/output device 2 outputs the data to the CP.
Send to U1.

In such a system, a signal line to the outside, e.g.
If a ground fault occurs in one part of the figure, an excessive current will flow through the ground fault part 14 and the fuse 10 will break.

At this time, through the level converter 11 and the failure output gate 12, the failure is transmitted to the digital input control device 2 through the error line 5.

Therefore, the CPU 1 detects that a failure has occurred and performs protective actions such as stopping the operation of the entire system.

According to the above-described operation, even if the fuse 10 is disconnected, its failure will cause malfunction of the entire input/output device.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to eliminate the drawbacks of the prior art described above and to provide an input/output device that can prevent malfunction of the entire system due to failure of one card.

FIG. 2 shows a block diagram of an input/output device according to an embodiment of the present invention, and the difference from the configuration shown in the first diagram is that the output of the matching circuit 6 is also applied to the fault output gate 12. That's true.

According to this configuration, when a failure occurs in a certain card, the failure output gate 12 operates only when the card is selected by the address line 3, and the failure is output to the digital input control device 2 through the error line 5. When another normal card is being addressed, no signal indicating a failure will appear on the error line 5.

Therefore, even if a trouble such as a broken fuse occurs in a certain card, it will not affect other cards and can be treated as a failure only in that card.

Similarly to other data, the fault occurrence signal can also be specified with a J address and placed on a path line such as an error line, thereby making it possible to identify the location of the fault, making this an extremely effective system. It is possible to plan the operation.

In the above embodiments, the fuse cutout S case was illustrated, but by providing a plurality of busbars as error lines, it is possible to deal with all other failures.

Furthermore, although the above embodiments have been explained by taking a digital system as an example, the present invention can be applied to any other system.

As described above, according to the present invention, even if a failure occurs in one or several places, the influence can be prevented from spreading widely and the range of failure can be minimized. It is possible to obtain a new input/output device.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a standard digital input/output device in a conventional computer control system, and FIG. 2 is a block diagram of an input/output device according to an embodiment of the present invention. Throughout each figure, the same reference numerals indicate the same or equivalent parts, 2 is a digital input control device, 3 is an address line,
5 is the error line, 6 is the matching circuit, 10 is the fuse, 1
2 is a fault output gate.

Claims (1)

[Claims] I. A plurality of terminal units connected to the CPU through a data line, an address line carrying address data for selecting one of the terminal units, and a controller in which the data on the address line specifies the own unit. a matching circuit provided for each terminal unit to determine the condition; a fault detection means provided for each terminal unit to perform fault detection; and a terminal unit addressed based on the matching circuit output and the fault detection means output. An input/output device characterized by comprising gate means for placing a failure detection signal only from an error line on an error line.