Rockwell Automation 1772-LV,D17726.6.1 A and I MNL MINI-PLC-2/15 PROCESSO - Manual (Page 50)

Assembly and Installation
Chapter 3
3Ć30
Bend the end of the wire to to the right and place the bare copper wire under the
pressure plate of the terminal screw. (Optionally, a spade lug can be used.)
Tighten the screw, and check that the wire is firmly in place. Bundle each
Module’s wires together and push them into the wiring duct. when completed,
the bundled wires should look similar to those shown in Figure 3.28.
Low Level DC I/O lines require shielded cable for signal transmission and must
be run in a separate wiring or in a duct containing only LOW LEVEL DC I/O
lines and Serial Communications Cables. use Belden 8761 Cable or its
equivalent. this cable has a single insulated twisted-pair with a foil shield
covering its entire length and a bare drain wire (Figure 3.29). The twisted-pair
consists of a signal wire and its signal return. The shield’s function is to reduce
the effect of induced noise at any point along the cable.
General procedures for connecting a shielded cable to a Field Wiring Arm are
described below. Consult the Module’s Product Data Sheet for specific wiring
connections.
Strip approximately 3 ft of insulation from the Belden 8761 Cable at the Field
Wiring arm end. Peel the shield away from the pair of insulated wires
(Figure 3.29). Either strip off the shield foil at the insulation or twist it together
with the bare drain wire thereby forming a single strand (Figure 3.30). it may be
necessary to insulate the shield with tape or shrink tubing along areas where it
might otherwise come into contact with wiring arm terminals.
Trim both insulated wires to 2-inch lengths and strip approximately 3/8-inch of
insulation from the end of each wire. The shield strand is left at its full 3- ft
length (Figure 3.31). Then, connect the insulated wires to the Field Wiring Arm
terminals.
The twisted shield strand must be properly grounded only at one end. The
recommended grounding point for the shield is at the I/o Chassis. Connect the
twisted shield strand to ground by placing it between the I/O Chassis mounting
bracket and the flat washer before the nut is tightened. A lug can be used
(Figure 3.32).