Campbell Scientific LLAC4 Four-channel, Low-Level AC Conversion Module - Manual (Page 9)

LLAC4 Four-Channel, Low-Level AC Conversion Module
TABLE 2. Control Port Compatibility
Datalogger Input (Hz) Control Port Measurement Type
CR1000
CR3000 400,000 C1,C2… C8 High Frequency
CR800 400,000 C1,C2,C3,C4 High Frequency
CR5000 5,000,000 C7,C8 High Frequency
CR23X 2,500 C5,C6,C7,C8 High Frequency
CR200(X) 1,000 P_LL,P_SW,C1,C2 High Frequency
CR10X 40 C6,C7,C8 Switch Closure
Comparing Table 1 to Table 2 suggests that the CR10X may not be able to read
either type of anemometer in high wind situations. However, all other
dataloggers would be appropriate choices.
4. Wiring
Most sensors that have a low-level AC output will have three wires: signal,
reference, and drain. The signal wire should go to P1 – P4 on the LLAC4 and
the reference and drain wires to a on the LLAC4. The LLAC4 also requires
that 12 V be applied to its 12 V terminal and G. This power should come from
the datalogger or the datalogger’s power supply.
A low-level AC signal on P1 will be converted to a 0-5 V square wave on the
D1 terminal. D1 can be wired to an appropriate datalogger control port that
can make high frequency measurements.
P1
P2
P3
FROM SENSOR
T
O DA
TALOGGER
P4
12V
G
D1
D2
D3
D4
G
12V
G
Control Port
G
12V
G
D1
G
DATALOGGER
SIG +
REF
DRAIN
P1
SENSOR
LLAC4
FIGURE 2. LLAC to TTL
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