Campbell CS650, Руководство по эксплуатации продукта

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Table 8-3: CS650 SDI-12 commands
SDI-12 command
(“a” is the sensor address)
Values returned Units
aM4!
1. Volumetric Water Content, q
2. Electrical Conductivity, s
3. Temperature
4. Permittivity, e
5. Period, t
6. Voltage Ratio, a
m
3
/m
3
dS/m
°C
μs
aM5!
..
aM9!
No Values Returned
?!
Returns the SDI-12 Address
aI!
CampbellSci, Operating System Version,
Product Serial Number
Campbell Scientific recommends using separate terminals when possible. However, multiple
CS650 sensors can connect to the same data logger control or U terminal. Each must have a
unique SDI-12 address. Valid addresses are 0 through 9, A through Z, and a through z. The CS650
ships with a default SDI-12 address of 0 unless otherwise specified at the time of ordering.
Change the SDI-12 address through
Device Configuration Utility (see A200 and Device
Configuration Utility (p. 13)) or with a terminal emulator in SDI-12 transparent mode (see SDI-12
sensor support (p. 41)).
8.2.1
M3!
and
M4!
commands
Typically, the M4! command is used to report volumetric water content, electrical conductivity,
temperature, permittivity, period, and voltage ratio. The
M4!
command reports the sensor
calculated values even if those values are likely to be erroneous.
The M3! command uses several logical tests built into the operating system to ensure that the
sensors do not report a number that is likely to be erroneous. Erroneous readings are either
outside the sensor operational limits or outside of published accuracy specifications. When one
of the following conditions occurs, the logical test replaces the calculated value with another
value such as 9999999 or NAN.
Permittivity < 0 or > 88
The equation used to convert period average and electrical conductivity values to permittivity is a
three-dimensional surface with two independent variables and eleven coefficients, plus an offset.
CS650 and CS655 Water Content Reflectometers 20