Campbell Scientific CR200/CR200X-series Dataloggers - Manual (Page 128)

Section 11. Programming Resource Library
logger issues aD1!, aD2!, etc., until all data are received. The limiting
constraint is that the total number of characters that can be returned to a aDv!
command is 35 characters (75 characters for aCv!). If the number of characters
exceed the limit, the remainder of the response are obtained with subsequent
aDv! commands wherein v increments with each iteration.
11.4.1.3.2 Continuous Measurements Command (aRv!)
Sensors designed to continuously monitor the measured phenomena, such as a
shaft encoder, do not require a measurement command (e.g., aMv!). They are
read directly with the aRv! command. If a sensor cannot perform continuous
measurements, then it responds to aRv! with the sensor address.
11.4.2 SDI-12 Communications
The CR200(X) supports SDI-12 communication through two modes –
transparent mode and programmed mode.
• Transparent mode facilitates sensor set-up and troubleshooting. It allows
commands to be manually issued and the full sensor response viewed.
Transparent mode does not log data.
• Programmed mode automates much of the SDI-12 protocol and provides
for data recording.
Multiple SDI-12 sensors can be connected to an SDI-12 input: . If multiple
sensors are wired to a single channel, each sensor must have a unique address.
SDI-12 standard v 1.3 sensors accept addresses 0 - 9, a - z, and A - Z.
If program mode communications is not successful, NAN will be loaded into the
first variable specified in SDI12Recorder () instruction. See Section NAN and
±INF (p. 153) for more information.
11.4.2.1 SDI-12 Transparent Mode
System operators can manually interrogate and enter settings in probes using
transparent mode. Transparent mode is useful in troubleshooting SDI-12
systems because it allows direct communication with probes.
Transparent mode may need to wait for commands issued by the programmed
mode to finish before sending responses. While in transparent mode, datalogger
programs may not execute. Datalogger security may need to be unlocked before
transparent mode can be activated.
Transparent mode is entered while the PC is in telecommunications with the
datalogger through a terminal emulator program. It is easily accessed through
Campbell Scientific datalogger support software, but may also be accessible
with terminal emulator programs such as Windows Hyperterminal. Keyboard
displays cannot be used.
To enter the SDI-12 transparent mode, enter the support software terminal
emulator. Click the “Open Terminal” button. A green “Active” indicator
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