Emerson Rosemount 3490 Series, Reference Manual

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Figure 4-18: Example Plotted Profile for Spherical Vessel
Normalized units (range 0.0 to 1.0) Actual level (X) and volume (Y) units
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
0.0
Y
X
200.0
400.0
600.0
800.0
1000.0
1200.0
1400.0
1600.0
1800.0
2000.0
0.4 0.8 1.2 1.6 2.0 2.4 2.8 3.2 3.6 4.0
0.0
Y
X
Parameters P114 (or P124) and P116 (or P126) need only be set to 1.0 for this method.
The volume or flow rate for the control unit PV is then derived from the plotted profile
using the live level measurements and interpolation between the plot points.
The X and Y points can also be converted (normalized) to be in the range 0.0 to 1.0 before
being entered manually (see
Figure 4-18 , left-hand graph). A value is then derived from
the plotted profile using the live level measurements that are already converted
(normalized) by the Transmitter Input Channel processing. Parameter P116 (or P126) is
then applied to the derived value to obtain the volume or flow rate for the control unit PV.
Note
Rosemount 3491/3493:
P113 to P116 are in the menus
SETUP
→
CONTROLLER
→
INPUT CHANNEL
→
Ch1 Profile,
Ch1 Pre scale, Ch1 NLP Data, and Ch1 Post Scale .
Note
Rosemount 3492:
P113 to P116 are in the menus
SETUP
→
CONTROLLER
→
PV CALCULATION
→
CHANNEL
1
→
Ch1 Profile, Ch1 Pre scale, Ch1 NLP Data, and Ch1 Post Scale .
P123 to P126 are in the menus
SETUP
→
CONTROLLER
→
PV CALCULATION
→
CHANNEL
2
→
Ch2 Profile, Ch1 Pre scale, Ch2 NLP Data, and Ch2 Post Scale .
Edit the 'look-up' table (P115/P125)
Prerequisites
Parameter P113/P123 must first be set to be “Special”.
Procedure
1. Navigate to the P115/P125 parameter screen.
Getting started Reference Manual
January 2021 00809-0100-4841
82 Emerson.com/Rosemount