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Connecting options
5-5-6
Twisted cables
5-6
Connecting options
Analogue and digital signals are less sensitive to interference if the cables
carrying them are "twisted". This is certainly to be recommended if screening
cannot be used. By twisting the wires the exposed areas are minimised. This
means that in the current circuit for any possible High Frequency (HF) interfer-
ence fields, no voltage can be induced. For a PLC it is therefore important that
the return wire remains in proximity to the signal wire. It is important that the
pair of wires is fully twisted over 360°.
The option cards are connected by the optional connectors X4 or X5 on the
control board see Fig. 35, page 41 and mounted above the control board. The
inputs and outputs of the option cards are connected in the same way as
other control signals.
Section 5-6
49
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