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3.
LINKING TO THE A2CCPU
MELSEC-A
3.1.3
Precautions when constructing the system
(1)
Flat cables, twisted-wire-pair cables and shielded three-
or five-core
PVC cables are used
for connections between the A2CCPU and the
A64RDC.
The maximum connecting distance between stations varies with the
cable diameter when twisted-wire-pair cables are used.
More than or equal to 0.2 mm2 to less than 0.5 mm2
,,........
50
m
0.5
mm and larger
............................................................
100 m
2
(2) The A64RDC requires an external
power supply
o f
24 VDC. Use an
A66PC power supply module
or a general-purpose stabilized
power
supply (24 VDC).
(3)
When supplying power from one power supply to multiple A64RDCs or
to remote I/O modules, select the proper cables and wiring route, taking
voltage drop into consideration.
V I
v 2
Stabilized
power
supply
/
1 2
I 1
+
1 2
\
R1
-
Y
\
1
R 2 -
1
I1
1 2
Remote
1/0
module
A64RDC
VI : Voltage drop between stabilized power supply and remote I/O module
Vz
: Voltage drop between remote 1 / 0 module and A64RDC
RI : Resistance between stabilized power supply and remote
I/O module
R2 : Resistance between remote
110
module and A64RDC
11
: Remote
1 / 0 module current consumption
1 2
: A64RDC current consumption
ICalculation of voltage drop1
VI
=
R I
x
(11
+
12)
V2
=
R2 x
I2
Remote 1/0 module receiving port voltage
(Remote I/O module receiving port voltage)
=
(Stabilized power supply voltage)
-
VI
(A64RDC receiving port voltage)
=
(Stabilized power supply voltage)
-
VI
-
V2
Connection is possible if the receiving port voltage of A64RDC is within the
range 15.6 V through 31.2 V.
3 - 3
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