Campbell cs215, Instruction Manual

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Appendix D. SDI-12 Sensor Support
D.1.1 Address Query Command (?!)
Command ?! requests the address of the connected sensor. The sensor replies
to the query with the address, a .
D.1.2 Change Address Command (aAb!)
Sensor address is changed with command aAb! , where a is the current address
and b is the new address. For example, to change an address from 0 to 2 , the
command is 0A2! . The sensor responds with the new address
b
, which in this
case is 2.
D.1.3 Send Identification Command (aI!)
Sensor identifiers are requested by issuing command aI! . The reply is defined
by the sensor manufacturer, but usually includes the sensor address, SDI-12
version, manufacturer’s name, and sensor model information. Serial number or
other sensor specific information may also be included.
D.1.4 Start Measurement Commands (aM!)
A measurement is initiated with M! commands. The response to each
command has the form atttnn, where
a = sensor address
ttt = time, in seconds, until measurement data are available
nn = the number of values to be returned when one or more subsequent D!
commands are issued.
D.1.5 Aborting a Measurement Command
A measurement command ( M! ) is aborted when any other valid command is
sent to the sensor.
D.1.6 Send Data Command (aD!)
This command requests data from the sensor. It is normally issued
automatically by the datalogger after measurement commands aM! . In
transparent mode, the user asserts this command to obtain data.
D.2 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. 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 is also accessible with
terminal emulator programs such as Windows HyperTerminal. Datalogger
keyboards and displays cannot be used.
D-2