Campbell CR800 Series, Operator'S Manual

Page: 249 / 598

Section 7. Installation
249
Public BatteryVolt
Public Temp(4)
BeginProg
Scan (5,Sec,0,0)
'Non-SDI-12 measurements here
NextScan
SlowSequence
Scan (5,Min,0,0)
SDI12Recorder (Temp(1),1,0,"M!",1.0,0)
SDI12Recorder (Temp(2),1,1,"M!",1.0,0)
SDI12Recorder (Temp(3),1,2,"M!",1.0,0)
SDI12Recorder (Temp(4),1,3,"M!",1.0,0)
NextScan
EndSequence
EndProg
However, problems 2 and 3 still are not resolved. These can be resolved by using
the concurrent measurement command, C! . All measurements will be made at
about the same time and execution time will be about 95 seconds, well within the
5 minute scan rate requirement, as follows:
Public BatteryVolt
Public Temp(4)
BeginProg
Scan (5,Sec,0,0)
'Non-SDI-12 measurements here
NextScan
SlowSequence
Scan (5,Min,0,0)
SDI12Recorder (Temp(1),1,0,"C!",1.0,0)
SDI12Recorder (Temp(2),1,1,"C!",1.0,0)
SDI12Recorder (Temp(3),1,2,"C!",1.0,0)
SDI12Recorder (Temp(4),1,3,"C!",1.0,0)
NextScan
EndProg
A new problem introduced by the C! command, however, is that it causes high
power usage by the CR800. This application has a very tight power budget.
Since the C! command reissues a measurement request immediately after
receiving data, the sensors will be in a high power state continuously. To remedy
this problem, measurements need to be started with C! command, but stopped
short of receiving the next measurement command (hard-coded part of the C!
routine) after their data are polled. The SDI12Recorder() instruction C
command (not
C!
) provides this functionality as shown in CRBasic example
Using Alternate Concurrent Command (aC)
(p. 251).
A modification of this
program can also be used to allow near-simultaneous measurement of SDI-12
sensors without requesting additional measurements, such as may be needed in an
event-driven measurement.