Campbell TB4, Product Manual

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Appendix C. CS700H Operation Details
C-6
TABLE C-4. Operating Modes
Auto/
Manual
X20
Cycle
Enable
X29
Heater
On/Off
X21
Snow
Enabled
X22 Snow Description
1 0 / 1 0 X X
Manual Mode:
The Cycle Enable flag X29 is used to force a
Heating Cycle. This is set or cleared by another
system at the site – as it determines whether
heating is required. When the Cycle Enable
flag is “0” the heaters are off. When the Cycle
Enable flag is “1” then the Heating Cycle is
started. (That is, the heater elements are
switched on and off to keep inside the funnel at
the SetPoint temperature X26.) The snow
sensor state can be read using the measure/data
commands, but its state is ignored when
controlling the heaters.
1 0 0 / 1 X X
Manual Mode:
The heater elements can be controlled directly
with the Heater On/Off flag X21. When the
flag is “0” the heaters are off, and when the
flag is “1” the heaters are on. Note that the
heaters must be cycled by the controlling
system in order to control the funnel
temperature. This mode must be used with
caution!
(X = Don’t Care)
C.6 SDI-12 Sensor Support
The CS700H will only communicate over SDI-12 when both its
sensor cable and power cable are connected (TABLE 7-2 and
TABLE 7-3 ).
C.6.1 Introduction
SDI-12, Serial Data Interface at 1200 baud, is a protocol developed to simplify
sensor and data logger compatibility. Only three wires are necessary — serial
data, ground, and 12 V. With unique addresses, multiple SDI-12 sensors can
connect to a single SDI-12 terminal on a Campbell Scientific data logger.
This appendix discusses the structure of SDI-12 commands and the process of
querying SDI-12 sensors. For more detailed information, refer to version 1.4 of
the SDI-12 protocol, available at www.sdi-12.org .
For additional information, refer to the SDI-12 Sensors | Transparent Mode
and SDI-12 Sensors | Watch or Sniffer Mode videos.
C.6.2 SDI-12 Command Basics
SDI-12 commands have three components:
NOTE