Campbell-scientific CR9000X Measurement and Control System Uživatelský manuál stáhnout pdf (Strana 53)

Overview

OV2.2 Measurements, Processing, Data Storage

The CR9000X divides a program into two tasks. The measurement task

manipulates the measurement and control hardware on a rigidly timed

sequence. The processing task processes and stores the resulting

measurements and makes the decisions to actuate controls.

The measurement task stores raw Analog to Digital Converter (ADC) data

directly into memory. As soon as the data from a scan is in memory, the

processing task starts. There are at least two Scan buffers allocated for this

raw ADC data (additional buffers can be allocated under program control),

thus the buffer from one scan can be processed while the measurement task is

filling another.

When a program is compiled, the measurement tasks are separated from the

processing tasks. When the program runs, the measurement tasks are

performed at a precise rate, ensuring that the measurement timing is exact and

invariant.

Processing Task: Measurement Task:

OV2.3 Data Tables

The CR9000X can store individual measurements or it may use its extensive

processing capabilities to calculate averages, maxima, minima, histograms,

FFTs, etc., on periodic or conditional intervals. Data are stored in tables such

as listed in Table OV2-1. The values to output are selected when running the

program generator or when writing a datalogger program directly.

Table OV2-1. Typical Data Table

TOA4 StnName Temp

TIMESTAMP RECORD RefTemp_Avg TC_Avg(1) TC_Avg(2) TC_Avg(3) TC_Avg(4) TC_Avg(5) TC_Avg(6)

TS RN DegC DegC DegC degC degC degC degC

Avg Avg Avg Avg Avg Avg Avg

2004-02-16 15:15:04.61 278822 31.08 24.23 25.12 26.8 24.14 24.47 23.76

2004-02-16 15:15:04.62 278823 31.07 24.23 25.13 26.82 24.15 24.45 23.8

2004-02-16 15:15:04.63 278824 31.07 24.2 25.09 26.8 24.11 24.45 23.75

2004-02-16 15:15:04.64 278825 31.07 24.21 25.1 26.77 24.13 24.39 23.76

See Section 2.4 Data Format on Computer for additional details on Logger

Memory and Data Structure.

Digital I/O task

Read and writes to ports and counters on CR9071

(ReadIO, WriteIO, TimerIO)

Processes measurements

Determines controls (port states) to set next scan

Stores data

Analog measurement and excitation sequence and

timing

Sets ports on 9060 Excitation Module (SetPort)

Sends interrupt to Processor task that reads and sets

ports/counters.

Polls CR9052 and CR9058 for Data

OV-21

1 2 ... 48 49 50 51 52 53 54 55 56 57 58 ... 441 442

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