4-5
Device Software Functions
4. The flow rate reading after warm-up should be between 29.97
and 30.03 ft/s.
5. If the reading is within the range, return the transmitter to the
original configuration parameters.
6. If the reading is not within this range, initiate an electronics trim
with the LOI or HART Communicator. The electronics trim takes
about six minutes to complete. No transmitter adjustments
are required.
Auto Zero Trim
The auto zero trim function initializes the transmitter for use with the
30 Hz coil drive mode only. Run this function only with the transmitter
and flowtube installed in the process. The flowtube must be filled with
process fluid at zero flow. Before running the auto zero function, be sure
the coil drive mode is set to 30 Hz.
Set the loop to manual if necessary and begin the auto zero procedure.
The transmitter completes the procedure automatically in about two
minutes. A symbol appears in the lower right-hand corner of the display
to indicate that the procedure is running.
Universal Auto Trim
(Model 8712U Only)
The universal auto trim function enables the Model 8712U to calibrate
flowtubes that were not calibrated at the Rosemount factory. (This
function is not available for the Model 8712C/H.) The function is
activated as one step in a procedure known as in-process calibration. If
your Rosemount flowtube has a 16-digit calibration number, in-process
calibration is not required. If it does not, or if your flowtube is made by
another manufacturer, complete the following steps for in-process
calibration.
1. If the flowtube coil resistance is unknown, perform steps a-c to
determine the resistance. Otherwise, skip to step 2.
a. Disconnect the flowtube from the transmitter.
b. Determine the resistance of the coil windings.
c. Reconnect the flowtube wiring.
2. Determine the flow rate of the process fluid in the flowtube.
NOTE
The flow rate in the line can be determined by using another flowtube
in the line, by counting the revolutions of a centrifugal pump, or by
performing a bucket test to determine how fast a given volume is filled
by the process fluid.
3. Complete the universal auto trim function.
When the routine is completed, the flowtube is ready for use.
HART Fast Keys 1, 2, 4, 4
LOI Key Aux. Function
HART Fast Keys 1, 2, 4, 5
LOI Key Aux. Function
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