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(4) Cables used for the modules connected to the head module
Use shielded cables for the cables which are connected to the I/O
modules and may be extended out of the control panel.
If a shielded cable is not used or not grounded correctly, the noise
immunity will not meet the specified value.
(a) Grounding a shielded cable
POINT
Grounding with a vinyl-coated wire soldered onto the shielded section of the shielded cable
as shown below is not recommended. Doing so will raise the high-frequency impedance,
resulting in loss of the shielding effect.
• Ground the shield of the shielded cable as close to the
module as possible so that the grounded cable will not be
affected by electromagnetic induction from ungrounded
cables.
• Ground the exposed shield section to large area on the
control panel. A clamp fitting can be used as shown in
below. In this case, apply a cover on the painted inner wall
surface of the control panel, which comes in contact with the
fitting.
Paint mask
Shielded cable
Vinyl-coated wire
Solderless terminal
Screw
Clamp fitting
Shielded cable
46
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