C.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.
C.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 aM!
or aMC!, 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 SDI-12 transparent mode
(p. 47) ), 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 aMC! or aCC!.
C.1.10 Continuous measurement command (aR0! … aR9!)
Sensors that are able to continuously monitor the phenomena to be measured can be read
directly with the R commands (R0! … R9!). The response to the R commands mirrors the Send
Data command (aD0!). A maximum of 75 characters can be returned in the <values> part of the
response to the R command.
ClimaVUE 50 Compact Digital Weather Sensor 46
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