Section 7. Installation
7.7.14.2 SDI-12 Recorder Mode
The CR800 can be programmed to act as an SDI-12 recording device or as an
SDI-12 sensor.
For troubleshooting purposes, responses to SDI-12 commands can be captured in
programmed mode by placing a variable declared As String in the variable
parameter. Variables not declared As String will capture only numeric data.
Another troubleshooting tool is the terminal-mode snoop utility, which allows
monitoring of SDI-12 traffic. Enter terminal mode as described in SDI-12
Transparent Mode
(p. 240), issue CRLF (<Enter> key) until CR800> prompt
appears. Type W and then <Enter>. Type 9 in answer to Select:, 100 in answer to
Enter timeout (secs):, Y to ASCII (Y)?. SDI-12 communications are then
opened for viewing.
The SDI12Recorder() instruction automates the issuance of commands and
interpretation of sensor responses. Commands entered into the SDIRecorder()
instruction differ slightly in function from similar commands entered in
transparent mode. In transparent mode, for example, the operator manually
enters aM! and aD0! to initiate a measurement and get data, with the operator
providing the proper time delay between the request for measurement and the
request for data. In programmed mode, the CR800 provides command and
timing services within a single line of code. For example, when the
SDI12Recorder() instruction is programmed with the M! command (note that the
SDI-12 address is a separate instruction parameter), the CR800 issues the aM!
and aD0! commands with proper elapsed time between the two. The CR800
automatically issues retries and performs other services that make the SDI-12
measurement work as trouble free as possible. Table SDI-12Recorder()
Commands
(p. 246) summarizes CR800 actions triggered by some
SDI12Recorder() commands.
If the SDI12Recorder() instruction is not successful, NAN will be loaded into the
first variable. See NAN and ±INF
(p. 466) for more information.
SDI-12 Commands for Programmed (SDIRecorder()) Mode
Command Name
SDIRecorder()
SDICommand
Argument
SDI-12 Command Sent
Sensor Response
1
CR800 Response Notes
Address Query
?!
CR800: issues a?! command. Only one sensor can be
attached to the C terminal configured for SDI-12 for this
command to elicit a response. Sensor must support this
command.
Change Address
Ab!
CR800: issues aAb! command
Concurrent Measurement
Cv!, CCv!
CR800: issues aCv! command
Sensor: responds with atttnn
CR800: if ttt = 0, issues aDv! command(s). If nnn = 0
then NAN put in the first element of the array.
Sensor: responds with data
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