B.1.8 Stopping a measurement command
A measurement command (
M!
) is stopped if it detects a break signal before the measurement is
complete. A break signal is sent by the data logger before most commands.
A concurrent measurement command (
C!
) is aborted when another valid command is sent to
the sensor before the measurement time has elapsed.
B.1.9 Send data command (aD0! … aD9!)
The Send Data command requests data from the sensor. It is issued automatically with every type
of measurement command (
aM!
,
aMC!
,
aC!
,
aCC!
). When the measurement command is a
M!
or a
MC!
, the data logger issues the
aD0!
command once a service request has been received
from the sensor or the reported time has expired. When the data logger is issuing concurrent
commands (
aC!
or
aCC!
), the Send Data command is issued after the required time has elapsed
(no service request will be sent by the sensor). In transparent mode (see
(p. 38) ), the user asserts this command to obtain data.
Depending on the type of data returned and the number of values a sensor returns, the data
logger may need to issue
aD0!
up to
aD9!
to retrieve all data. A sensor may return up to 35
characters of data in response to a
D
command that follows an
M!
or
MC!
command. A sensor
may return up to 75 characters of data in response to a
D
command that follows a
C!
or
CC!
command. Data values are separated by plus or minus signs.
Command:
aD0!
(
aD1!
…
aD9!
)
Response:
a<values><CR><LF>
or
a<values><CRC><CR><LF>
where:
a
= the sensor address
<values>
= values returned with a polarity sign (+ or –)
<CR><LF>
= terminates the response
<CRC>
= 16-bit CRC code appended if data was requested with a
MC!
or
aCC!
.
B.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. Data logger security may need to be unlocked before activating the
transparent mode.
Transparent mode is entered while the computer is communicating with the data logger through
a terminal emulator program. It is accessed through Campbell Scientific data logger support
BaroVUE™10 Digital Barometer
38
