Campbell CR800 Series, Operator'S Manual

Page: 194 / 598

Section 7. Installation
194
of information (eight states with one bit per state). To store the same information
using a 32 bit BOOLEAN data type, 256 bits are required (8 states * 32 bits per
state).
When programming with BOOL8 data type, repetitions in the output processing
DataTable() instruction must be divisible by two, since an odd number of bytes
cannot be stored. Also note that when the CR800 converts a LONG or FLOAT
data type to BOOL8, only the least significant eight bits of the binary equivalent
are used, i.e., only the binary representation of the decimal integer
modulo divide
(p. 505)
256 is used.
Example:
Given: LONG integer 5435
Find: BOOL8 representation of 5435
Solution:
5435 / 256 = 21.2304687
0.2304687 * 256 = 59
Binary representation of 59 = 00111011 (CR800 stores
these bits in reverse order)
When
datalogger support software
(p. 86)
retrieves the BOOL8 value, it splits it
apart into eight fields of -1 or 0 when storing to an ASCII file. Consequently,
more memory is required for the ASCII file, but CR800 memory is conserved.
The compact BOOL8 data type also uses less comms band width when
transmitted.
CRBasic example Bool8 and Bit Shift Operators
(p. 196)
programs the CR800 to
monitor the state of 32 "alarms" as a tutorial exercise. The alarms are toggled by
manually entering zero or non-zero (e.g., 0 or 1) in each public variable
representing an alarm as shown in figure
Alarms Toggled in Bit Shift Example
(p.
195).
Samples of the four public variables FlagsBool8(1) , FlagsBool8(2) ,
FlagsBool8(3) , and FlagsBool8(4) are stored in data table Bool8Data as four
one-byte values. However, as shown in figure Bool8 Data from Bit Shift
Example (Numeric Monitor)
(p. 195),
when viewing the data table in a
numeric
monitor
(p. 506),
data are conveniently translated into 32 values of True or False .
In addition, as shown in figure Bool8 Data from Bit Shift Example (PC Data File)
(p. 196),
when datalogger support software
(p. 86)
stores the data in an ASCII file, it is
stored as 32 columns of either -1 or 0 , each column representing the state of an
alarm. You can use variable aliasing
(p. 138)
in the CRBasic program to make the
data more understandable.