Campbell Scientific CS650 and CS655 Water Content Reflectometers - Manual (Page 26)

CS650 and CS655 Water Content Reflectometers
TABLE 6-4. CS650 SDI-12 Commands
SDI-12 command
(“a” is the sensor
address) Values Returned Units
aM! 1) Volumetric Water Content, θ
2) Electrical Conductivity, σ
3) Temperature
m 3 /m 3
dS/m
°C
aM1! 1) Permittivity, ε
2) Electrical Conductivity, σ
3) Temperature
dS/m
°C
aM2! 1) Period, τ
2) Voltage Ratio, α
3) Temperature
µ Sec
°C
aM3! 1) Volumetric Water Content, θ
2) Electrical Conductivity, σ
3) Temperature
4) Permittivity, ε
5) Period, τ
6) Voltage Ratio, α
m 3 /m 3
dS/m
°C
µ Sec
aM4! .. aM9! No Values Returned
?! Returns the SDI-12 Address
aI! CampbellSci, OS version, Product
Serial Number
Up to 10 CS650’s may be connected to the same datalogger control port as
long as each one has a unique SDI-12 address. The CS650 ships with a default
SDI-12 address of 0 unless otherwise specified at the time of ordering. The
SDI-12 address may be changed through DevConfig software (see Section 6.4,
A200 and Device Configuration Utility) or with a terminal emulator in SDI-12
transparent mode (see Appendix B).
SDI-12 communication is established using the CRBasic instruction
SDI12Recorder for CRBasic dataloggers or the Edlog program instruction
P105 SDI-12 Recorder. See Appendix B for more detail on SDI-12
communication.
6.5.1 Use of Multiplexers
Multiplexers such as Campbell Scientific’s AM16/32B may be used to connect
up to 32 CS650 probes to a single control port. When using multiplexers, the
simplest configuration is for all probes to have the same SDI-12 address.
When multiplexing CS650 probes, the switched 12V channel should be used so
that power to the sensor may be turned off under program control before the
multiplexer switches to the next channel.
Failure to turn off the switched 12 volt channel before
clocking the multiplexer will result in damage to the
multiplexer relays.
CAUTION
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