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3.
Power Supply
4.
Physical Connections
CAUTION
CAUTION
The data logger power supply is typically used to power the SDM-AO4A. Use
a rechargeable lead-acid battery, float charged by AC power or a solar panel,
for long-term operation. The PS150 and PS200 power supplies are ideal for
this application. The BPALK alkaline battery pack is rated at 7 amp-hours and
will power one SDM-AO4A for less than one month. This supply is not
recommended for continuous long-term operation.
The SDM-AO4A may also be powered from an external 12 Volt supply,
independent from the data logger supply. The low side of an external 12 Volt
supply should be connected to data logger ground and not directly earth
grounded.
FIGURE
4-1
shows the front panel of the SDM-AO4A. The terminal block
(p. 3)
on the left is used for connection to the data logger and the terminal block on
the right provides the continuous analogue output. The two ground ports on
the left block are identical and connected internally.
TABLE
4-1
describes the terminal block connections. Multiple SDM-
(p. 3)
AO4As may be used by connecting the data logger side of one SDM-AO4A to
the next as long as each SDM-AO4A is set to a unique address.
The CABLE5CBL-L or similar cable is used to connect the module to the data
logger. A 1-ft cable length should be sufficient when both data logger and
module are housed within an ENC12/14 enclosure; a 2-ft length may be
required if the data logger and SDM-AO4A are housed at opposite ends of an
ENC16/18 enclosure.
CRBasic data loggers should use the SDMSpeed() instruction if the cable
length is longer than 20 feet (see Section 7.1.2, SDMSpeed() Instruction
Cables connecting the terminals of the data logger and SDM
device must be as short as possible to minimize the risk of
corruption of the signal and damage from induced surges.
When first powered up, the device is in low-power mode until the first valid
SDM instruction is received. In this mode, outputs are pulled to GND.
The order of connections is critical. ALWAYS CONNECT
GROUND FIRST, followed by 12V and then the Control
Ports.
Shielded twisted pair cabling is recommended for wiring the continuous
analogue outputs.
SDM-AO4A Four-Channel Analogue Output
).
(p. 8)
2
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