Emerson Tescom ER5000 Series User Manual page 139

ER5000 — The ERTune™ Program: Basic Features
To optimize the display when both additional variables have been
added to the Plot Screen
In many applications, the ranges for the first and second additional
variable will vary widely. For example, it is a common practice
to use the first additional variable to display feedback from the
ER5000's 0–100 psig / 0–6.9 bar internal sensor and use the second
additional variable to display feedback from an external sensor
that has a range that is considerably larger, such as 0–30,000 psig /
0–2068 bar.
Since the display for the secondary axis is set by the range and unit
of measurement for the first additional variable, a display based on
psig / bar can give unsatisfactory results:
• If the secondary axis is set to the smaller range of the internal
sensor, feedback from the external sensor will often be
beyond the maximum of the display.
• If the secondary axis is set to the larger range of the external
sensor, the feedback from the internal sensor will be difficult
to differentiate.
The "best of both worlds" approach in this scenario is to set the
range for both variables to 0–100%, rather than using a unit of
measure based on pressure values. At this setting, both variables
will display meaningful response curves in the Plot Screen despite
the difference in their ranges.
The one disadvantage to this approach is that actual pressure
values must be extrapolated from the percentage values
generated by and displayed by the ERTune
important for you to track pressure values, set both variables ranges to
the actual pressure ranges of the sensors. You will be able to track the
values in real time using the Value Field
reviewing the data files from data acquisition. You will also be able
to track the sensor selected as the first additional variable visually
in the Plot Screen display.
program. If it is more
™
for each variable and by
139