Advantech 5000 Series - Manual (Page 236)

Appendix A
Host Computer
Any computer or terminal that can output in ASCII format over either
RS-232 or RS-485 can be connected as the host computer. When
only RS-232 is available, an ADAM RS-232/RS-485 Converter is
required to transform the host signals to the correct RS-485 protocol.
The converter also provides opto-isolation and transformer -based
isolation to protect your equipment.
Power Supply
For the ease of use in industrial environments the ADAM-5000
systems designed to accept industry standard +24 V
DC
unregulated
power. Operation is guaranteed when using any power supply
between +10 and +30 V
DC
. Power ripples must be limited to 100 mV
peak to peak while the voltage in all cases must be maintained between
+10 and +30 V
DC
. When the systems are powered remotely the
effects of line voltage drops must be considered.
All systems onboard switching regulators to sustain good efficiency
over the 10-30 V input range, therefore, we can assume that the actual
current draw is inversely proportional to the line voltage. The
follow- ing example shows how to calculate the required current that
a power supply should be able to provide.
Assume that a +24 V
DC
will be used to power an ADAM-5000/485 and
four ADAM-5017 input modules. The distance from Power supply to
modules is not so big that significant line voltage drop will occur. One
ADAM-5000/485 system and one ADAM-5017 module consume a
maximum of 1.0 W (ADAM-5000) and 1.2 W (ADAM-5017). The total
required power will equal 1 W + 4 x 1.2 W = 5.8 Watts. A power
supply of +24 V
DC
should, therefore, be able to supply a minimal current
of 5.8
/ 24 = 0.25 Amps.
Small systems may be powered by using wall-mounted modular power
supplies. Also when systems operate on long communication lines
(>500 feet) it is often more reliable to power the systems locally with
modular power supplies. These inexpensive units can easily be
obtained from any electronics retail store.
The power cables should be selected according to the number of
systems connected and the length of the power lines. When using a
ADAM-5000 A-3