Emerson Guided Wave Radar Level and Interface Transmitters 3300 - Manual (Page 64)

Reference Manual
00809-0100-4811, Rev CA
February 2006
Rosemount 3300 Series
4-12
4 and 20 mA Points
When setting the range values, it is possible to enter the values directly using
the keypad on the Field Communicator, or you may use actual values (HART
command [1, 3, 4, 2]). Keep in mind that the 20 mA value should be below the
Upper Dead Zone. If the 20 mA point is set to a point within the Dead Zone
the full range of the analog output is not used.
Also make sure that the 20 mA value is below the Upper Null Zone (UNZ).
(This parameter may be used if there are measurement problems in the upper
part of the tank, see Section 6: Disturbances at the Top of the Tank). The UNZ
is equal to zero in the default configuration.
The 4 mA point should be above the Lower Dead Zone. If the 4 mA point is
set to a point within the Dead Zone or below the probe end (tank bottom for
example), the full range of the analog output is not used.
See Section 2: Dead Zones for more information on the size of Upper and
Lower Dead Zones.
Figure 4-7. Range Values
HART Comm 1, 3, 4, 3
20 mA Upper Range Value (URV)
Upper Dead Zone
Product Level
Interface Level
Lower Dead Zone
4 mA Lower Range Value
(LRV)
Upper Reference Point
Rang
e 0-10
0 %
4 20 MA PO
INT
S