information on parsing strings, see Input Programming Basics (p. 251).
CRBasic Example 57. Using an SDI-12 Extended Command
'This program example demonstrates the use of SDI-12 extended commands. In this example,
'a temperature measurement, tt.tt, is sent to a CH200 Charging Regulator using the command
'XTtt.tt!'. The response from the CH200 should be '0OK', if 0 is the SDI-12 address.
'
'Declare Variables
Public PTemp As Float
Public SDI12command As String
Public SDI12result As String
'Main Program
BeginProg
Scan(20,Sec,3,0)
PanelTemp(PTemp,250)
SDI12command = "XT" & FormatFloat(PTemp,"%4.2f") & "!"
SDI12Recorder(SDI12result,1,0,SDI12command,1.0,0)
NextScan
7.9.18.3 SDI-12 Sensor Mode
The CR1000 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. 267), issue CRLF (<Enter> key) until CR1000> 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 SDI12SensorSetup() / SDI12SensorResponse() instruction pair programs
the CR1000 to behave as an SDI-12 sensor. A common use of this feature is the
transfer of data from the CR1000 to other Campbell Scientific dataloggers over a
single-wire interface (terminal configured for SDI-12 to terminal configured for
SDI-12), or to transfer data to a third-party SDI-12 recorder.
Details of using the SDI12SensorSetup() / SDI12SensorResponse() instruction
pair can be found in the CRBasic Editor Help. Other helpful tips include:
Concerning the Reps parameter in the SDI12SensorSetup(), valid Reps when
expecting an aMx! command range from 0 to 9. Valid Reps when expecting an
aCx! command are 0 to 20. The Reps parameter is not range-checked for valid
entries at compile time. When the SDI-12 recorder receives the sensor response
of atttn to a aMx! command, or atttnn to a aCx! command, only the first digit n,
or the first two digits nn, are used. For example, if Reps is mis-programmed as
123, the SDI-12 recorder will accept only a response of n = 1 when issuing an
aMx! command, or a response of nn = 12 when issuing an aCx! command.
279
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