3-7
Section
Sharing the Same Power Supply
41
Because of space and cost difficulties involved in preparing individual power
supplies, sharing the same power supply may be unavoidable. If this is the case,
take the following precautions.
•
Be sure to keep the I/O power supply separate.
•
When the communications and internal circuit power supply is shared, wiring
the network as shown in configuration A is recommended. Do not wire the net-
work as shown in configuration B because it will generate more noise than the
network in configuration A.
Note The lower voltage boundary of the internal circuit power supply must be higher
than that of the communications power supply. To meet the voltage specifica-
tions for the internal circuit power supply, be sure to follow the specifications pro-
vided in 3-3 Sharing the Communications Power Supply.
Configuration A
Same power supply
for communications
and internal circuit
Communications
power supply
Internal circuit
power supply
V– V+ – +
24VDC
24VDC
V– V+ – +
V– V+ – +
24VDC
V– V+ – +
24VDC
Communications
power supply
Internal circuit
power supply
Communications
power supply
Internal circuit
power supply
Communications
power supply
Internal circuit
power supply
Same power supply
for communications
and internal circuit
Configuration B
