Campbell Scientific CS650 and CS655 Water Content Reflectometers - Manual (Page 12)

CS650 and CS655 Water Content Reflectometers
5.2 Electrical Specifications
Sensor Output: SDI-12
Serial RS-232
Warmup Time: 3 s
Measurement Time: 3 ms to measure
600 ms to complete SDI-12 command
Power Supply
Requirements: 6 Vdc to 18 Vdc
Must be able to supply 45 mA @ 12 Vdc
Maximum Cable Length: 610 m (2000 ft) combined length for 1 – 10
sensors connected to the same datalogger
control port
Electromagnetic
Compatibility: Πcompliant (EMC compliant performance
criteria available upon request)
Meets EN61326 requirements for protection
against electrostatic discharge and surge
External RF sources can affect CS650
measurements. CS650 circuitry should be
located away from radio transmitter aerials
and cables, or measurements ignored during
RF transmissions.
5.2.1 Current
Active (3 ms): 45 mA typical @ 12 Vdc
(80 mA @ 6 Vdc, 35 mA @ 18 Vdc)
Quiescent: 135 µA @ 12 Vdc
Average Current Drain: I = 0.09n + [3.5 + 0.024(n-1)]n/s
I = average current in milliamps
n = number of CS650’s
s = number of seconds between
measurements
(see FIGURE 5-1)
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