Note: Descriptions are shown in the official language in which they were submitted.
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This jllV~iltiOIl relates to an input/output (I~o)
data cable for use in interconnecting the mod~llar
components of a programmable controller.
A programmable controller comprises a processor
which controls the operation of thc system being controlled
by receiving logic signals from a plurality of input
modules and feeding logic signals to a plurality of
f~ output modules, the input and output modules being
~J connected to the processor through respective data
c~bles. Also the logic level voltage must be fed to
the input modules, output modules and processor.
The logic signals which pass between the processor
and the input and output modules are subjected to
considerable interference especially in the ca~e when
the system being controlled is a machine. Accordingly,
it is necessary to ensure that the interconnecting data
cables have high immunity frvm such interference,
It is known to interconnect the I/O modules and the
processor by means of rigid bus~bars and data cables, the
rigid structure allowing high immunity to be designed into
the bus-bars and data cables. However, such rigid
systems severely restrict the versatility of the
controller as regards its physical layout.
Flexible ribbon conduc-tors are known but these do
not have the re~uired imm.units7 and also suffer from high
inductive losses.
It is an object o~ thc present invention to obviate
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or mitigate the above disadvantages.
~ccordina to one aspect of the present invention
there is provided an illpUt/OUtpUt data cable for a
programmable controller, the cable comprising a flexible
5 laminate made up of three layers, each layer having a
conducting part and an insulating part, the first of
said layerl being adapted to be connected to the system
ground, the second of said layers being adapted to carry
O a logic voltage, and the third of said layers having a
10 plurality o~ signal tracks for carrying data signals,
wherein said first and second layers are adjacent.
According to a second aspect of the present invention
the~e is provided an input/output data cable ~or a
programmable controller, the cable comprising a flexible
15 laminate made up of two layers, each layer having a
conducting part and an insulating part, the conducting
part of the first of said layers having a single conducting
O track extending substantially across the whole width of
the layer, and the conducting part of the second of said
20 layer being formed by a conducting track extending over
paxt of the width of said layer and b~ a plurality of
signal tracks ~or carryirlg datn slgnals.
Lmbodiments O;e the present invention will now be
described, by way of example, with reference to the
25 accompanying drawings 5 in which:
Fig. 1 is a top plan view O:e one embocliment of a
data cable made in accordance with said one aspect of
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q;
the present invention;
Fig. 2 is a sectional view taken along the line II -
II of Fig. 1,
Figs. 3a, 3b and 3c are plan views of the three
5 layers of the data cable of Fig. l;
Figs~ 4a and 4b are perspective and elevational
views respectively of a connector for use with the data
0 cable of Fig. l; and
Figs. 5~ anfl 5b are plan views of the two layers
10 of one embodiment of a data cable made in accordance
with said second aspect of the present invention.
Referring to Figs. 1 - 4 of the drawings, an input/
output data cable 1 for interconnecting the modular
components of a programmable controller comprises a
15 flexible laminate assembly made up of three layers 10,
11 and 12 each having a conducting part and an insulating
part, The layer 11 is used for the logic voltage; the
layer 12 is used f or the system ground and layer 10 is
used for data signals.
As illustrated in Figs. 3a and 3b the layers 11 and
12 each comprise a single copper track 110 and 120 attached
to an lnsulatillg polyester strip 111 and 121 respectively.
At the e~llds of each of the copper tracks 110 and 120 there
are pro~ided contact tabs 114 and 124 respectively f or
co~nection with a connector as hereinafter described.
Tlle layer 10 comprises a plurality of side-by-side
signal e;lrrying conductors 100 extending along the layer
10 and ~ttached to an insulating polyester strip 101.
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The dal,a cable is ~`ormed by glueing the layers
together one on top of the other to form a laminate
struct-lre so that the logic voltage carrying layer 11
and system ground layer 12 are adjacent and the data
signal carrying layer 10 is on the exterior. ~n
additional insulating strip 133 is laid on top of the
layer 12. 1
The resultant assembly comprises a flexible laminated
cable having relatively wide area,tracks the adjacent
layers being extremely close to each other. This
arrangement provides high immunity and additionally
minimises inductive losses along the data signal tracks
due to the relative closeness ~f the logic voltage
carrying layer 11.
A suitable terminal 40 is illustrated i~ Fig. 4,
and is adapted to be attached to each end of the data
cable ]. The terminal 40 has a plurality of spaced
contacts 41, end ones 41a and 41b contacting with the
respective tabs 114 and 124 of the voltage level layer
11 and ground layer 12. Central contacts 41c engage
respective tracks of the data s~gnal layer 10,
The above described arrangement wherein the data
signal layer 10 is adjacent the logic voltage carrying
layer 11 i5 suitable for a system which has been designed
to fail safe on occurence of a high logic voltage leYel.
Thus, in the event of a short circuit between the data
signal layer 10 and the adJacent layer, i.e. the layer
11, the system being controlled by the controller will
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~ail sa:Ce.
Clearly i~ the system being controlled has been
designed to fail safe on a logic level OI zero then the
data carrying layer 10 should be placed adjacent the
grounded layer 12.
These two alternatives are possible with the data
cable of t}~is invention since the data signal carrying
0 layer is ad~jacent only ore other layer.
Referring now to Figs. 5a and 5b a data cable is
made up of two layers 21 and 22. The first of the
layers 21 comprises a single copper track 210 attachecl
to an insulating polyester strip 211, a contact tab 214
is provided for connection with a conductor of the t~pe
illustrated in Figs. 4a and 4_.
The second layer 22 comprises a copper track 220
extending across substantially half of the width of the
layer 22 and a plurality of side-by-side signal carrying
conductors 2~5. The track 22(~ and cQnductors 225 are
attached to an insulating polyester strip 221 and the
track 220 is provided with a contact tab 224.
The data cable is formed by glueing the layers 21
and 22 together one on top of the other to form a laminate
structure. In this embodiment of the data cable the
logic voltage can be applied either to the track 21~
- 25 or track 224 depending on the system design, ground being
connected to the other track.
