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MELSEC-Q
4 SETUP AND PROCEDURES BEFORE STARTING THE OPERATION
4.6.3 Twisted bus system (when using a shielded twisted pair cable)
(1) Wiring precautions
(a) Wiring a shielded twisted pair cable
When wiring a shielded twisted pair cable, prevent the noise and surge
induction, referring to the following.
1) Do not install a shielded twisted pair cable together with the main
circuit, high-voltage cable, or load line and also do not bring them
close to each other. (Keep a distance of 100mm (3.94 inches) or more
between them.)
2) Provide as much distance as possible between the shielded twisted
pair cables and the power supply of the module or I/O signal cables.
3) Do not use any of shielded twisted pair cables (e.g. One pair among
three pairs) for supplying power.
(b) Connecting terminating resistors
For the network modules at both ends, connect the DA and DB by a
terminating resister (110 , 1/2W) provided with the module.
(c) Connecting/disconnecting a shielded twisted pair cable
Shut off the external power supply for the system in all phases.
(2) Connection of cable
(a) Connection method
For connection between DAs and between DBs, use shielded twisted pair
cables.
No cabling is required for (DG).
In addition, connect terminating resistors for stations at both ends.
DA
DB
(DG)
FG
Shielded twisted pair cable
SLD
DA
DB
(DG)
FG
SLD
DA
DB
(DG)
FG
SLD
DA
DB
(DG)
FG
SLD
Terminating
resistor
(110 , 1/2W)
Terminating
resistor
(110 , 1/2W)
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