Abort Softkey; Analog Mode And Hart Mode Interaction; Hart Calibration; Hart Mode Menus For Adjustment - Fluke 754 User Manual

754
Users Guide

Abort Softkey

The Abort softkey stops the communication operation in
process, and gives control to the previous screen. From
the Active Device screen, Abort calls up the browser, in
which you can see the list of connected transmitters.
Analog Mode and HART Mode
Interaction
Analog mode is usual Product operation, as given in the
753/754 Users Manual. HART Communication mode
starts when r is pushed.
Push r to change between HART and analog modes, or
push  to change to analog mode from HART mode.
This lets the transmitter automatically set up analog mode
for applicable measure and source functions, if
necessary.
For supported transmitters, the change to analog mode
goes to the MEASURE/SOURCE screen. This makes it
easy to continue with an "as found" calibration.
For generic transmitters, the change to analog mode
makes you choose the MEASURE or SOURCE screen,
from which you select the applicable function.
For supported or generic transmitters, when you push r
to return to HART mode, the Active Device screen is
shown. The HART serial communication connection stays
active as you change between HART and analog modes.
12

HART Calibration

An analog transmitter has one step of electrical
conversion from a measured physical parameter to
a 4-20 mA current loop output. A HART transmitter
has the three blocks. See Figure 12.
It can be necessary to examine and adjust the Input
block, the Output block, or both. For example, if your
application requires the Primary Variable (PV) to be
correct when read by a host computer, you must calibrate
the Input stage.
If your application requires that the 4-20 mA current
output value accurately show what the Input block is
measuring, you must calibrate the Input and Output block.
Transmitters in multidrop systems, in which more than
one is wired in parallel, do not use their Output blocks.
Their analog outputs are all held at an idling level of 4 mA
no matter what the Input block measures.

HART Mode Menus for Adjustment

Sensor Trim in HART mode is when you adjust the Input
block. Output Trim is when you adjust the Output block.
These adjustments are made from the Service menu.
For pressure transmitters, Pressure Zero Trim is an
additional adjustment. This adjustment is the same as
when you set the lower sensor point at zero. All three
operations are energized from the HART mode Service
menu.