Campbell CR10 PROM Instruction Manual download pdf (Page 25)

APPENDIX B. SERIAL COMMUNICATIONS WITH THE CSAT3

B-4

TABLE B-5. Converting u

Wind from Word 2

Range Word 4 Range Code Conversion Output Resolution

b07 b06 (mm s

-1

)

01 1

wind (m s

-1

) = word 2 ∗ 0.001 ∗ 0.25

0.25

11 0

wind (m s

-1

) = word 2 ∗ 0.001 ∗ 0.50

0.50

20 1

wind (m s

-1

) = word 2 ∗ 0.001 ∗ 1.00

1.00

30 0

wind (m s

-1

) = word 2 ∗ 0.001 ∗ 2.00

2.00

The speed of sound reported by the CSAT3 is the average between the three sonic paths. The

relationship to find the speed of sound is given in Table B-6. Word 3 must be converted to a base 10

representation before applying the equation.

TABLE B-6. Converting Speed of Sound from Word 3

Conversion Output Resolution

(mm s

-1

)

(°C @ 25°C)

speed of sound (m s

-1

) = word 3 ∗ 0.001 + 340.0

1 0.0017

B.4 WORD 4

Word 4 contains diagnostic information and the reporting range of u

, u

, and u

wind speed. The

diagnostic flags, bits b15 through b12, describe the status of the anemometer. A flag is on if the bit is

set high. All the flags are on while the anemometer is acquiring signals or is in a lost trigger state.

TABLE B-7. Decoding the Diagnostic Flags from Word 4

Bit Set High Description Comment

b15 Difference in the speed of sound

between the three non orthogonal

axes is greater than 2.360 m s

-1

(~ 4°C @ 25°C)

The anemometer path length may have

been altered or the anemometer head is

broken.

b14 Poor signal lock There may be an obstruction in the

anemometer path or on the transducer

face.

b13 Sonic signal amplitude too high An obstruction, in the anemometer path or

on the transducer face, was removed.

b12 Sonic signal amplitude too low There may be an obstruction in the

anemometer path or on the transducer

face.

Bits b11 through b06 are used in determining the range of the wind speed reported in words 0 through 2.

Bits b05 through b00 are a diagnostic counter. This counter increments once per measurement. The

minimum value is 0 and the maximum is 63. The counter wraps from 63 to 0 when the maximum value

is incremented by one.

TABLE B-8. Special Case – Not a Number

Not a Number Word 0 Word 1 Word 2 Word 3 Word 4

Conditions hex base 10 hex base 10 hex base 10 hex base 10 hex base 10

Not Available 8000 -32768 8000 -32768 8000 -32768 8000 -32768 F03F 61503

Lost Trigger 8000 -32768 8000 -32768 8000 -32768 8000 -32768 F000 61440

1 2 ... 20 21 22 23 24 25 26 27 28 29 30

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Campbell CR10 PROM Instruction Manual Page 25

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