JPH04304698A - Exclusion control system during package installation error - Google Patents

Abstract

PURPOSE:To prevent the generation of a disturbance imposed to the input or the output to a different package by giving a high impedance to an input terminal or an output terminal of a self-package when it is recognized that a different package has been mounted on a unit when a self-package is mounted. CONSTITUTION:A first package 11 and a second package 21 comprises inverter 12, 22 which are input-pulled up by means of their respective pull-up resisstors 13 and 23 and whose output terminals are connected with control terminals of their respective tri-state buffers 14 and 24. When the first package 11 is mounted to a unit, if it is recognized that at least one of the second packages 21 is already mounted to the unit, the input terminal or the output terminal of the first package 11 is arranged to be in a high impedance-state. This construction makes it possible to protect the output 34 of the first package already 11 mounted previously from being affected by a disturbance.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to an exclusive control system when a package is incorrectly mounted, and particularly to a plurality of packages that are mounted in one unit and whose input terminals or output terminals are connected to each other through the backboard of this unit. At the same time 1
Concerning an exclusive control method that allows implementation of only one package.

0002

[Prior Art] Conventional exclusive control methods for incorrectly mounting packages include a method of changing the connector type for each package to prevent incorrect mounting, and unifying the power supply terminals of packages to at least prevent failures. The method was adopted.

0003

[Problem to be Solved by the Invention] This conventional exclusive control method when a package is incorrectly mounted is a method in which the connector type is changed for each package, but a different connector must be prepared for each package type, which increases the number of connector types. , and there is a problem that it cannot be applied if there is a condition that the connectors must be of the same type. Another problem is that the method of unifying the power supply terminals of packages cannot solve the phenomenon of signal interruption due to incorrect mounting.

0004

[Means for Solving the Problems] The exclusive control method when a package is incorrectly mounted according to the present invention is implemented in a plurality of units that are mounted on one unit and whose input terminals or output terminals are connected to each other on the backboard of the unit. In the exclusive control method of the package, means for recognizing the mounting state of other packages other than the own package in the unit, and means for recognizing the mounting state of the other packages in the unit when the own package is mounted in the unit; Each of the plurality of packages is provided with means for setting the input terminal or the output terminal of the own package to high impedance when it is recognized that the package is mounted.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention. The inputs of the first package 11 and the second package 21 are pulled up by pull-up resistors 13 and 23, respectively, and the outputs are pulled up by tri-state buffers 14 and 2, respectively.
It has inverters 12 and 22 connected to the control terminals of 4, and a first package mounting state signal 33 which is the output of the inverter 12 and a second package mounting state signal 33 which is the output of the inverter 22.
The mounting status signal 32 of the package is crossed on the backboard 31 and sent to the inverter 22 of the other package.
Connected to 12 inputs. Further, the output 34 of the first package and the output 35 of the second package are wired-OR connected on the backboard 31.

Next, the operation will be explained.

[0008] Under normal operating conditions, the first package 1
1 and the second package 21 are not mounted at the same time. Now, consider a situation where only the first package 11 is mounted and the second package 21 is not mounted. At this time, the mounting status signal 32 of the second package becomes open, so
The input of the inverter 12 of the first package 11 is “H”
level, the output of the inverter 12 becomes "L" level, enables the tri-state buffer 14, makes the output 34 of the first package active, and sets the mounting state signal 33 of the first package to "L" level. L”
level.

If the second package 21 is incorrectly mounted in this state, the input of the inverter 22 is at the "L" level, so the output of the inverter 22 becomes the "H" level, causing the output of the tri-state buffer 24 to go high. - The impedance is set, and the mounting state signal 32 of the second package is set to "H" level to enter a stable state. The operating principle described above makes it possible to prevent disturbance from being caused to the output 34 of the first package that has been previously mounted.

Note that even if the outputs of three or more packages are wired-OR connected on the backboard 31, the same operation as described above occurs, and only the package mounted first is valid.

Further, in this embodiment, the case where the package output is wired-OR has been described, but it is obvious that the present invention can be applied and the same effect can be obtained even when the package input is wired-ORed.

0012

Effects of the Invention As explained above, the present invention provides for a plurality of packages that are mounted on one unit and whose input terminals or output terminals are connected to each other on the backboard of the unit, to prevent mounting of other packages. It has a means for recognizing the status and a means for setting the input terminal or output terminal of the own package to high impedance if it is recognized that another package is already mounted on the unit when the own package is mounted. Therefore, even if a package is incorrectly mounted, it is possible to prevent the already mounted input terminal or output terminal from disturbing the input or output of another wired-ORed package.

[Brief explanation of drawings]

FIG. 1 is a block diagram of one embodiment of the present invention.

[Explanation of symbols]

11 First package 12, 22 Inverter 13, 23 Pull-up resistor 14, 24 Tri-state buffer 21
Second package 31 Backboard 32 Second package mounting status signal 33
First package mounting status signal 34
Output of package 35 Output of second package

Claims (1)

[Claims] Claim 1: In an exclusive control system for a plurality of packages mounted in one unit, whose respective input terminals or output terminals are connected to each other by a backboard of the unit, means for recognizing a mounting state on a unit; and when recognizing that at least one of the other packages has already been mounted on the unit when the own package is mounted on the unit, the input of the own package; An exclusive control method when a package is incorrectly mounted, characterized in that each of the plurality of packages is provided with a terminal or means for setting the output terminal to high impedance.