Campbell CR510, Operator'S Manual

Page: 17 / 264

CR510 OVERVIEW
OV-5
OV2.2 PROGRAM TABLES, EXECUTION
INTERVAL AND OUTPUT INTERVALS
The CR510 must be programmed before it will
make any measurements. A program consists
of a group of instructions entered into a
program table . The program table is given an
execution interval which determines how
frequently that table is executed. When the
table is executed, the instructions are executed
in sequence from beginning to end. After
executing the table, the CR510 waits the
remainder of the execution interval and then
executes the table again starting at the
beginning.
The interval at which the table is executed
generally determines the interval at which the
sensors are measured. The interval at which
data are stored is separate from how often the
table is executed, and may range from samples
every execution interval to processed
summaries output hourly, daily, or on longer or
irregular intervals.
Programs are entered in Tables 1 and 2.
Subroutines, called from Tables 1 and 2, are
entered in Subroutine Table 3. The size of
program memory can be fixed or automatically
allocated by the CR510 (Section 1.5).
Table 1 and Table 2 have independent
execution intervals, entered in units of seconds
with an allowable range of 1/8 to 8191 seconds.
Subroutine Table 3 has no execution interval;
subroutines are only executed when called from
Table 1 or 2.
OV2.2.1 THE EXECUTION INTERVAL
The execution interval specifies how often the
program in the table is executed, which is
usually determined by how often the sensors
are to be measured.
Unless two different
measurement rates are needed, use only one
table
. A program table is executed sequentially
starting with the first instruction in the table and
proceeding to the end of the table.
Table 1.
Execute every x sec.
0.125 < x < 8191
Instructions are executed
sequentially in the order they
are entered in the table. One
complete pass through the
table is made each execution
interval unless program
control instructions are used
to loop or branch execution.
Normal Order:
MEASURE
PROCESS
CHECK OUTPUT COND.
OUTPUT PROCESSING
Table 2.
Execute every y sec.
0.125 < y < 8191
Table 2 is used if there is a
need to measure and
process data on a separate
interval from that in Table 1.
Table 3.
Subroutines
A subroutine is executed
only when called from Table
1 or 2.
Subroutine Label
Instructions
End
Subroutine Label
Instructions
End
Subroutine Label
Instructions
End
FIGURE OV2.2-1. Program and Subroutine Tables