Campbell Scientific CR6 CR6 Measurement and Control System - Page 231

Measurements from 1 to 100 Hz

Page 231 highlights

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

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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
Per Burst
N/A
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