Campbell Scientific CR6 CR6 Measurement and Control System - Page 231
Measurements from 1 to 100 Hz
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Section 7. Installation normally suspended to allow processing to catch up. Suspended measurements equate to lost measurement opportunities and may not be desirable. 600 Hz and 2000 Hz measurements (measurements exceeding 100 Hz) have duty cycles less than 100%. Need to work out rates for the CR6. Table 40. Summary of Analog Voltage Measurement Rates Maximum Rate 100 Hz 600 Hz 2000 Hz Number of Simultaneous Inputs Multiple inputs Fewer inputs One input Maximum Duty Cycle 100% < 100% < 100% Maximum Measaurements N/A Per Burst Variable 65535 Description Near simultaneous measurements on multiple channels Up to 8 sequential differential or 16 single-ended channels. Buffers are continuously "recycled", so no skipped scans. Near simultaneous measurements on fewer channels Buffers maybe consumed and only freed after a skipped scan. Allocating more buffers usually means more time will elapse between skipped scans. A single CRBasic measurement instruction bursts on one channel. Multiple channels are measured using multiple instructions, but the burst on one channel completes before the burst on the next channel begins. Analog Terminal Sequence Differential: 1, 2, 3, 4, 5, 6, 7, 8, then repeat. Single-ended: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, then repeat. Differential and single-ended: 1, 2, 1, 2, and so forth. 1, 1, 1... to completion, then 2, 2, 2... to completion, then 3, 3, 3..., and so forth. Excitation for Bridge Measurements Provided in instruction. Provided in instruction. Provided in instruction. Measurements per excitation must equal Repetitions CRBasic Programming Highlights Suggest using Scan() / NextScan with ten (10) ms scan interval. Program for the use of up to 10 buffers. See CRBasic example Measuring VoltSE() at 100 Hz Use Scan() / NextScan with a 20 ms or greater scan interval. Program for the use of up to 100 buffers. Also use SubScan() / NextSubScan with 1600 µs sub-scan and 12 counts. See CRBasic example Measuring VoltSE() at 200 Hz Use Scan() / NextScan with one (1) second scan interval. Analog input Channel argument is preceded by a dash (-). See CRBasic example Measuring VoltSE() at 2000 Hz 7.9.14.1 Measurements from 1 to 100 Hz Assuming a minimal CRBasic program, measurement rates between 1 and 100 Hz are determined by the Interval and Units parameters in the Scan() / NextScan instruction pair. The following program executes VoltSE() at 1 Hz with a 100% duty cycle. 231