Final Storage Format - Campbell CR510 Operator's Manual

As an example of a negative value, the
datalogger returns BF 82 0C 49 HEX.
Data byte 1 = BF HEX.
Data byte 2 to 4 = 82 0C 49 HEX (or 8522825
decimal).
Data byte 1 is converted to binary to find the
Sign. BF HEX = 10111111 BINARY.
The most significant bit is 1 so the Sign is
NEGATIVE.
The exponent is found by subtracting 40 HEX
from the remaining least significant bits.
Converting the binary to hexadecimal, 111111
BINARY = 3F HEX (or 63 decimal).
3F - 40 HEX = FF FF FF FF FF HEX. Or in
decimal: 63 - 64 = -1.
Exponent is -1 decimal.
The binary representation of Data bytes 2 to 4
is: 10000010 00001100 01001001.
Summing all the fractional values: 2
-13 -14 -18 -21
2 + 2 + 2 + 2 + 2
Using the estimate method to find the Mantissa =
82 0C 49 HEX / 1 00 00 00 HEX (or 8522825 /
16777216) which is 0.50800 decimal.
The value is then (-)0.508*2
-0.254.
As an example of a positive value, the
datalogger returns 44 D9 99 9A HEX.
Data byte 1 = 44 HEX.
Data byte 2 to 4 = D9 99 9A HEX (or 891290
decimal).
Data byte 1 is converted to binary to find the
Sign. 44 HEX = 01000100 BINARY.
NOTE: Don't lose the leading zero!
The most significant bit is 0 so the Sign is
POSITIVE.
The exponent is found by subtracting 40 HEX
from the remaining least significant bits.
-1 -7
+ 2 +
-24
= 0.50800.
-1
which equals
APPENDIX B. BINARY TELECOMMUNICATIONS
Converting the binary to hexadecimal, 1000100
BINARY = 44 HEX (or 68 decimal).
44 - 40 HEX = 4 HEX. Or in decimal:
68 - 64 = 4.
Exponent is 4 decimal.
The binary equivalent of Data bytes 2 to 4 is:
11011001 10011001 10011010.
Summing all the fractional values:
-1 -2 -4 -5
2 + 2 + 2 + 2 + 2
-17 -20 -21
2 + 2 + 2 + 2
Using the estimate method to find the Mantissa =
D9 99 9A HEX / 1 00 00 00 HEX (or 14260634 /
16777216) which is 0.85000 decimal.
The value is then (+)0.85*2
13.60.
If appropriately requested by a J command,
Final Storage data, if any, will immediately
follow the input location data. Refer to the
datalogger manual for a description of how to
decode Final Storage data in CSI's binary data
format. Final Storage data will be limited to not
more than 1024 bytes per K command.
The K command data is terminated with 7F 00
HEX (a unique binary format code) followed by
two signature bytes. Refer to the datalogger
manual for the meaning and calculation of the
signature bytes. The signature in this case is a
function of the first time byte through the 7F 00
HEX bytes. Calculate the signature of the bytes
received and compare with the signature received
to determine the validity of the transmission.
B.2 FINAL STORAGE FORMAT
CR510 data is formatted as either 2 byte LOW
Resolution or 4 byte HI Resolution values. The
first two bytes of an Output Array contain a unique
code (FC Hex) noting the start of the Output Array
and the Output Array ID, followed by the 2 or 4
byte data values. At the end of the data sent in
response to the telecommunications F command a
2 byte signature is sent (see below).
Representing the bits in the first byte of each
two byte pair as ABCD EFGH (A is the most
significant bit, MSB), the byte pairs are
described here.
-8 -9 -12 -13
+ 2 + 2 + 2 + 2
-23
= 0.85000.
4
which equals
-16
+
B-3