Campbell CR10 PROM, Operator'S Manual

Page: 39 / 253

1-1
SECTION 1. FUNCTIONAL MODES
1.1 PROGRAM TABLES - *1, *2, AND *3
MODES
Data acquisition and processing functions are
controlled by user-entered instructions
contained in program tables. Programming can
be separated into 2 tables, each having its own
user-entered execution interval. A third table is
available for programming subroutines which
may be called by instructions in Tables 1 or 2 or
by a special interrupt. The *1 and *2 Modes are
used to access Tables 1 and 2. The *3 Mode is
used to access Subroutine Table 3.
When a program table is first entered, the
display shows the table number in the ID field
and 00 in the data field. Keying an "A" will
advance the editor to the execution interval. If
there is an existing program in the table, keying
an instruction location number prior to "A" will
advance directly to the instruction (e.g., 5 will
advance to the fifth instruction in the table).
1.1.1 EXECUTION INTERVAL
The execution interval is entered in units of
seconds as follows:
1/64 ...1 seconds, in multiples of 1/64 (0.015625)
1 ......31.875 seconds, in multiples of 1/8 (0.125)
32 .....8191 seconds, in multiples of 1 second
Execution of the table is repeated at the rate
determined by this entry. The table will not be
executed if 0 is entered. Entries less than 32
seconds will be rounded to a valid interval if
they are within 1/512 (0.00195) second of a
valid interval, otherwise error E41 will be
displayed. Entries greater than 32 seconds are
rounded to the nearest second.
The sample rate for a CR10 measurement is the
rate at which the measurement instruction can be
executed (i.e., the measurement made, scaled
with the instruction's multiplier and offset, and the
result placed in Input Storage). Additional
processing requires extra time. The throughput
rate is the rate at which a measurement can be
made and the resulting value stored in Final
Storage. The maximum throughput rate for fast
single-ended measurements with standard
software is 192 measurements per second (12
measurements repeated 16 times per second).
If the specified execution interval for a table is
less than the time required to process that
table, the CR10 finishes processing the table
and waits for the next occurrence of the
execution interval before again initiating the
table (i.e., when the execution interval has
elapsed and the table is still executing, that
execution is skipped). Since no advantage is
gained in the rate of execution with this
situation, it should be avoided by specifying an
execution interval adequate for the table
processing time.
NOTE: Whenever the processing time of
the user's program exceeds a table's
execution interval, an error is logged in
memory. The number of overrun errors
can be displayed and reset in the *B mode
(Section 1.6) or using the Telecommunica-
tions A command (Section 5.1). An
overrun will also cause decimal points to
appear on both sides of the sixth digit of
the CR10KD. The decimal points will not
appear around the G in LOG if the *0 Mode
is entered before the overrun occurs.
In some cases, the processing time may exceed
the execution interval only when the Output Flag
is set and extra time is consumed by final Output
Processing. This may be acceptable. For
example, suppose it is desired to sample some
phenomena every 0.125 seconds and output
processed data every 10 minutes. The
processing time of the table which does this is
less than 0.125 seconds except when output
occurs (every 10 minutes). With final output the
processing time is 1 second. With the execution
interval set at 0.125 seconds, and a one second
lag between samples once every 10 minutes, 8
measurements out of 4800 (.17%) are missed:
an acceptable statistical error for most
populations.
1.1.2 SUBROUTINES
Table 3 is used to enter subroutines which may
be called with Program Control Instructions in
Tables 1 and 2 or other subroutines. The group
of instructions which form a subroutine starts
with Instruction 85, Label Subroutine, and ends
with Instruction 95, End (Section 12).