Campbell Scientific CR1000KD CR1000 Measurement and Control System - Page 133
Pipeline Mode
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Section 7. Installation 7.7.3.6.1 Pipeline Mode Instructions or commands that are handled by each sequencer are listed in table Task Processes (p. 133). The measurement task sequencer is a rigidly timed sequence that measures sensors and outputs control signals for other devices. The digital task sequencer manages measurement and control of SDM devices. The processing task sequencer converts analog and digital measurements to numbers represented by engineering units, performs calculations, stores data, makes decisions to actuate controls, and performs serial I/O communication. The CR1000 executes these tasks in either pipeline or sequential mode. When a program is compiled, the CR1000 evaluates the program and determines which mode to use. Mode information is included in a message returned by the datalogger, which is displayed by the support software. The CRBasic Editor precompiler returns a similar message. Note A program can be forced to run in sequential or pipeline modes by placing the SequentialMode or PipelineMode instruction in the declarations section of the program. Some tasks in a program may have higher priorities than other tasks. Measurement tasks generally take precedence over all others. Priority of tasks is different for pipeline mode and sequential mode. Table 15. Task Processes Measurement Task Digital Task Processing Task • Analog Measurements • Excitation • Read Pulse Counters • All SDM • Processing instructions, except SDMSI04() and • Output SDMI016() • Serial I/O • SDMSIO4() • Read Control Ports (GetPort()) • Set Control Ports (SetPort()) • VibratingWire() • PeriodAvg() • CS616() • SDMIO16() • ReadIO() • WriteIO() • Expression evaluation and variable setting in measurement and SDM instructions • Calibrate() Pipeline mode handles measurement, most SDM, and processing tasks separately, and possibly simultaneously. Measurements are scheduled to execute at exact times and with the highest priority, resulting in more-precise timing of measurement, and usually more-efficient processing and power consumption. Pipeline scheduling requires that the program be written such that measurements are executed every scan. Because multiple tasks are taking place at the same time, 133