SequentialMode, PipeLineMode (Processing Modes)
SequentialMode and PipeLineMode instructions are used to determine how the datalogger will handle instruction processing in the program.
Syntax
SequentialMode
PipeLineMode
Example
In the following CR1000X program, the SequentialMode instruction is used to force the datalogger to execute all instructions in the order they appear in the program. This allows the barometric pressure reading to be made only once per hour (i.e., conditionally, based on time).
This program was written for a CR1000X, but other dataloggers can use similar code (voltage ranges, channel numbers, or other parameters may need to be changed to reflect the specifications of the datalogger).
'CR1000X Series Datalogger
SequentialMode
Public AirTemp, WetTemp, Bar_kPA, VpKPA
DataTable (EnvData,1,-1)
DataInterval (0,1,Min,10)
Sample (1,AirTemp,FP2)
Sample (1,WetTemp,FP2)
Sample (1,Bar_kPA,FP2)
Sample (1,VpKPA,FP2)
EndTable
BeginProg
Scan (1,Sec,3,0)
'Code for HMP45C measurements AirTemp and
RH:
'Code for measuring Barometer, based on
time
If TimeIntoInterval(59,60,Min) Then PortSet(C2,1)
If TimeIntoInterval(0,60,Min) Then
Bar_kPa=Bar_kPa*0.1
PortSet(C2,0)
EndIf
WetDryBulb (VpKPA,AirTemp,WetTemp,Bar_kPA)
CallTable EnvData
NextScan
EndProg
Remarks
The datalogger has two processing modes: sequential mode A CRBasic program execution mode wherein each statement is evaluated in the order it is listed in the program. and pipeline mode A CRBasic program execution mode wherein instructions are evaluated in groups of like instructions, with a set group prioritization.. In sequential mode, instructions are executed by the datalogger sequentially as they occur in the program. In pipeline mode, measurement tasks and processing tasks are handled separately (in a "measurement task sequencer" and a "processing task sequencer") and executed concurrently. See Processing Modes for a list of instructions run in the "measurement task sequencer" and instructions run in the "processing task sequencer."
When running in PipelineMode, the datalogger allocates two buffers for processing tasks by default. The number of buffers can be increased in the BufferOption parameter of the Scan instruction. The buffers can be set to no fewer than two (0, 1, or 2, can be entered for the parameter, but two buffers will still be allocated). Additional buffers can be allocated if more are needed when extensive processing is taking place at certain times during program execution. Keep in mind, however, that these buffers use memory (See the BufferOption parameter in the help for the Scan instruction for additional information). The MaxBuffDepth value in the datalogger Status table can be monitored to help understand the optimum number of buffers to allocate for a program.
The default mode of operation is pipeline mode A CRBasic program execution mode wherein instructions are evaluated in groups of like instructions, with a set group prioritization.. However, when the datalogger program is compiled, the datalogger analyzes the program instructions and automatically switches to sequential mode A CRBasic program execution mode wherein each statement is evaluated in the order it is listed in the program. if the code requires it. The datalogger can be forced to run in either mode by placing the appropriate instruction at the beginning of the program before the BeginProg instruction.
In pipeline mode, it takes less time for the datalogger to execute each scan of the program. However, because processing can lag behind measurements, there could be instances, such as when turning on a sensor using the SW12 instruction, that the sensor might not be turned on at the correct time to make the measurement. In such instances, another instruction should be used (for example, PortSet) or the datalogger should be set to run in SequentialMode.
See Also