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12 faster measurement rates – Campbell Scientific CR1000 Measurement and Control System User Manual

Page 231

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Section 7. Installation

231

 

FlagsBool8(1) = Flags

AND

&HFF

'AND 1st 8 bits of "Flags" & 11111111

FlagsBool8(2) = (Flags

>>

8)

AND

&HFF

'AND 2nd 8 bits of "Flags" & 11111111

FlagsBool8(3) = (Flags

>>

16)

AND

&HFF

'AND 3rd 8 bits of "Flags" & 11111111

FlagsBool8(4) = (Flags

>>

24)

AND

&HFF

'AND 4th 8 bits of "Flags" & 11111111


CallTable

(Bool8Data)

NextScan

EndProg

 

7.8.12 Faster Measurement Rates

Certain data acquisition applications require the CR1000 to make analog
measurements at rates faster than once per second (> 1 Hz

(p. 456)

). The CR1000

can make continuous measurements at rates up to 100 Hz, and bursts

(p. 448)

of

measurements at rates up to 2000 Hz. Following is a discussion of fast
measurement programming techniques in association with VoltSE(), single-ended
analog voltage measurement instruction. Techniques discussed can also be used
with the following instructions:

VoltSE

()

VoltDiff

()

TCDiff

()

TCSE

()

BrFull

()

BrFull6W

()

BrHalf

()

BrHalf3W

()

BrHalf4W

()

The table Summary of Analog Voltage Measurement Rates

(p. 232),

summarizes the

programming techniques used to make three classes of fast measurement: 100-Hz
maximum-rate, 600-Hz maximum-ate, and 2000-Hz maximum-rate. 100-Hz
measurements can have a 100% duty cycle

(p. 453).

That is, measurements are not

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%.