Table of Contents
Advertisement
SECTION
3.
INSTRUCTION SET
BASICS
counter. The
loop
counter
is
added to
the
indexed value to determine
the actual input
location
the instruction acts
on.
Normally the
loop
counter is incremented by
1
after each
pass through
the
loop.
Instruction 90, Step
Loop Index, allows
the increment step to
be
changed.
See Instructions 87 and 90, Section
12,
for more details
To index an input location
(4
digit integer) key C
after keying the value but before entering the
parameter. Two minus signs
(-)
will
be
displayed to
the right
of
the parameter.
3.5
VOLTAGE RANGE AND
OVERRANGE DETECTION
The RANGE code parameter on InpuVOutput
Instructions is used to specify the
full scale
voltage range
of
the measurement and the
integration period for
the measurement (Table
3.5-1).
Select
the smallest full scale range that
is
greater than or equal to the full scale output of
the sensor being
measured.
Using
the sma
possible range
will result
in
the best resolution
for
the measurement.
Two different integration sequences are
possible. The slow integration, 16.67
milliseconds,
is
one
60
Hz
cycle
and rejects
noise from
60 Hz AC line power as
wellas
having better rejection
of random noise than
fast integration. A PROM with 50Hz rejection
is
available for countries whose electric utilities
operate at 50Hz (Appendix
B).
When
a
voltage input exceeds the range
programmed, the value
stored
is
the maximum
negative number, displayed
in
the
*6 Mode
as
-99999.
In
output data
from Final Storage this
becomes -6999 in low resolution or
-99999.
in
high resolution.
An input voltage greater than +8 volts on one of
the analog inputs
will result
in
errors and
possible overranging on the other
analog inputs
Voltages greater
than
16
volts may permanently
damage the 21X.
TABLE
3.5-1. lnput Voltage
Ranges and Codes
Range Code
Slow
16.67ms
Integ.
1
2
3
4
5
Full Scale Range
Fast
250;rs
Integ.
11
t5
millivolts
12
t15
millivolts
13
t50
millivolts
14
t500
millivolts
15
t5000
millivolts
Resolution"
0.33
microvolts
1.
microvolts
3.33
microvolts
33.3
microvolts
333.
microvolts
*Differential measurement, resolution
for single-ended measurement
is twice value shown.
3.6
OUTPUT PROCESSING
Most
Output Processing Instructions require
both
an intermediate processing operation and
a
final processing
operation.
For example, when
the
Average Instruction,
71
,
is executed,
the
inte
rmediate processing
operation increments a
sample count and adds
each new Input Storage
value to
a
cumulative
total residing
in
lntermediate
Storage.
When
the Output Flag
is
set, the final processing operation divides the
total by the number of sample counts, stores the
resulting average in Final Storage and zeros
the
value in Inlermediate Storage so that
the
process starts over with
the next execution.
Final Storage
is
the default destination of data
output by Output Processing Instructions
(Sections OV1.2,
1.5,
2.1).
Instruction
80 may
be used to direct output
to
Input Storage or
to
FinalStorage.
Output Processing Instructions requiring
intermediate processing sample
the specified
input location(s) each time the
Output
I
3-2
is
executed, NOT necessarily each time
the
Advertisement
Table of Contents
