Perform Analog Output Verification; Perform Level Deviation Monitoring - Emerson Rosemount 5408 Reference Manual

Safety Instrumented Systems (4-20 mA only)
5.
6.
8.8.4

Perform analog output verification

Compare HART Primary Variable digital value with analog output reading. Verify that the
deviation is within the pass limit.
Procedure
1.
2.
3.
4.
8.8.5

Perform level deviation monitoring

Use the analog output to obtain level (or distance) reading and compare with an
independent level measurement. Verify that the deviation is within the pass limit.
Procedure
1.
(2) Command 2: Analog output current and Percent of range Command 3: Device variables (PV, SV, TV, and QV) and Analog output current
144
Perform a two-point level measurement verification of the transmitter in the
measuring range. Compare with independent measurement (e.g. the BPCS level
sensor).
a. Select Service Tools > Variables > Process.
b. Verify the current level or distance reading with an independent measurement is
within the safety deviation of 2%.
Note
The inaccuracy of the independent measurement needs to be considered.
c. Move the surface in the tank at least 10% of the full measuring span (level
0-100%).
d. Repeat steps (a) to (b) for the second point.
Remove the bypass and otherwise restore normal operation.
Obtain the loop current as a digital value, do one of the following:
• In Rosemount Radar Master Plus, under Overview, select All Variables and read
the current analog output value.
• Read HART command 2 or 3 via the host system.
Obtain the loop current as an analog value (e.g. by using the safety logic solver or
using the TEST terminal, see
Compare the current values.
Verify the current deviation is within the safety deviation of 2% (±0.32 mA).
Note
The inaccuracy of safety logic solver needs to be considered.
Obtain the level (or distance) measurement value derived from the analog output
(e.g. by checking measurement value in safety logic solver).
(2)
Section 7.4.4).
Reference Manual