Campbell CS230, Руководство по эксплуатации продукта

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Appendix C. SDI-12 Sensor Support
C-4
TABLE C-2. Example aM! Sequence
0D0!
The data logger immediately issues the first D
command to collect data from the sensor.
0+.859+3.54<CR><LF>
The sensor immediately responds with the sensor
address and the two values.
C.2.7 Stopping a Measurement Command
A measurement command ( M! ) is stopped if it detects a break signal. A break
signal is sent by the data logger before most commands.
C.2.8 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!). The data
logger issues the aD0! command once a service request has been received from
the sensor. In transparent mode (Appendix C.3 , SDI-12 Transparent Mode
(p. C-
4)
), 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! command.
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
C.2.9 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.
C.3 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 software or other terminal emulator
programs. Data logger keyboards and displays cannot be used.