Geometrical instruments
Patent
1984-12-06
1986-06-17
Abrams, Neil
Geometrical instruments
339186M, H01R 909, H01R 1364
Patent
active
045952507
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a modular apparatus, such as an apparatus for the acquisition, processing and/or restitution of digital signals, of the type comprising programmable auto-controls, computers and industrial data-processing, instrumentation or transmission systems, incorporating electronic cards connected to a bus, particularly a printed circuit, by means of coded connections. The electronic cards can be, for example, central-unit cards, supply cards or input or output cards.
It is known that apparatuses of the programmable auto-control type are usually accommodated in a container, the bottom of which conceals a permanently installed printed circuit and has towards the interior of the container rows of connections, each of which is adapted to receive corresponding connections arranged at the edge of an electronic card mounted, for example, in a flat housing. The housings are arranged side by side in the container. The front face of at least some of the housings, which during operation is substantially in the plane of the aperture of the container, receives a terminal-box, by means of which the card is connected to an external central unit or to the members to be controlled or monitored.
The cards or their housings can be separated from the container. The readily understandable need has therefore arisen to prevent the possibility of mounting a given card or housing anywhere but in the location assigned to it in the container. Assembly and also work on repairs, tests or conversions of an existing apparatus are thereby made easier.
German utility model No. 6,605,363 discloses a mechanical coding device intended for preventing connection errors. According to this device, each of the two components to be connected possesses a comb. The teeth of each comb are directed towards those of the other comb. The teeth of the two combs are broken selectively, so that each remaining tooth is located opposite a broken tooth of the other comb.
This device has many disadvantages. The coding work is long and requires a high degree of attention. It is difficult to check. If a tooth is broken as the result of a coding error, the component has to be changed. Moreover, careful thought is needed to determine the codings which can be used in practice and those which should not be assigned. In fact, it is necessary to avoid the possibility of a device, the code of which consists of a relatively restricted number of remaining teeth, being connected to another device having a different code and possessing more broken teeth including those corresponding to the remaining teeth mentioned above.
German application No. 2,534,775 describes a device comprising, on the one hand, a comb with removable teeth and, on the other hand, a grid, of which the cells adapted to receive the teeth of the comb can be closed by means of attached plugs. Coding involves arranging the teeth on the comb according to a certain configuration and closing all the cells of the grid except those located opposite the teeth of the comb. This system has all the disadvantages of the device with breakable teeth, except that, in the second device, the coding errors can be rectified without waste.
German application No. 2,416,107 describes a third device which is specific to the apparatuses of the type covered by the invention and in which the housing carries teeth adapted to engagement in a profiled slide carried by the container. The profile of the teeth and that of the slide must match one another for the engagement of the housing to be possible. It is true that, during coding, there are no longer the difficulties and, where appropriate, the risks described with regard to the two known devices mentioned above. However, it is necessary, here, to make as many moulded teeth/slide pairings as there are different codes provided for all the equipment to be produced. This is very costly. Without special precautions at the design stage, there is even here the risk that relatively narrow teeth may be engaged incorrectly in a slide which is wider than them.
On the ot
REFERENCES:
patent: 4032213 (1977-06-01), Snyder et al.
patent: 4159862 (1979-07-01), Funck et al.
patent: 4398779 (1983-08-01), Ling
Joly Jean
Oehlert Yves
Abrams Neil
La Telemecanique Electrique
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