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MELSEC-Q
5 PROCEDURES BEFORE SYSTEM OPERATION
5.5.3 Precautions against wiring
As one of the requirements to give full play to QJ71PB92D’s functions and make up
the system with high reliability, it is necessary to have an external wiring unsusceptible
to an influence of noise. Precautions against external wiring of QJ71PB92D is
described below.
(1)
Do not route the wire of QJ71PB92D close to or bundle it together with the main
circuit and high-tension lines, or the load-carrying lines from other than the PLC.
Otherwise, the module may be susceptible to an influence of noise and surge
induction.
(2)
The wires from the input/output modules of the PLC should be away from the
communication cable of PROFIBUS-DP interface module as far as possible as
shown in the figure below.
Shield twisted-pair cable
Wiring of input
module
Wiring of output module
Shielded covering
Pow
e
r s
upp
ly
mod
u
le
P
L
C CP
U
Inpu
t m
o
du
le
Inpu
t m
o
du
le
O
u
tput modul
e
O
u
tput modul
e
QJ71PB9
2D
(3)
Grounding
(a)
When the PROFIBUS-DP interface module is used, the FG and LG
terminals of the power supply module of the PLC should basically be
grounded.
(b)
If communication cannot be performed after grounding because of
abnormal voltage applied to the FG terminal, the module may be used
without grounding.
