4.5 POINT DISPLAYS 9, 10, 11, AND 12 - SINGLE LOOP WITH
HORIZONTAL TREND
The Single Loop With low-resolution Horizontal Trend display is illustrated in Figure 4-10. A typical
display with a high alarm indication is shown first on sheet 1. On sheet 2 the tag name is shown ap-
pearing at the top of the display. The left side of the Single Loop With Horizontal Trend Display
has a trend indicator that provides 2% resolution of the last 40 process variable samples taken.
The time frame for the trend indicator is determined by the sample rate of the process variable
(e.g., a sample taken every 2 seconds X 40 samples on the indicator = an 80 second trend indica-
tor time frame). The indicator time frame appears on the left side of the display, directly below the
graph baseline (shown as 80 S in the illustration). The right side of the display has a 50 segment
vertical axis line with numeric values above and below it indicating its upper and lower ranges.
Left of the vertical axis line is the process variable bar. The top of the PV bar connects to the
trend indicator. On the immediate right of the vertical axis line is the setpoint arrowhead. Alphanu-
meric legends and values are listed below the graph baseline, under the vertical axis lower range
value. They are the engineering units (e.g.,
PERCENT
), setpoint (
SP
) or ratio (
RA
), process vari-
able (
PV
), and output value (
OV
) legends. The status indicators also appear below the graph base-
line, but to the left of the
SP
and
PV
legends. There are no alarm limit indicators on this graphical
display; however, the horn overlay appears at the top of the display and the alarm overlay appears
directly below it.
Figure 4-10. Point Displays 9 - 12, Single Loop with Horizontal Trend
(Sheet 1 of 2)
HORN OVERLAY (A009
= ’wALARMx’, L065 = 1,
AND L063 = 0)
HIGH ALARM OVERLAY
PROCESS VARIABLE HAS
MOVED ABOVE
CONFIGURED UPPER
ALARM LIMIT (ALARM
INDICATORS DO NOT
APPEAR ON TREND
DISPLAY)
Section 4. Operator Displays
4-23
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