Introduction
Release 3
34-ST-25-20 MC Toolkit User Manual
5
9/06
range. That is, corrections are applied at the Lower Range Value (LRV) and the Upper Range Value
(URV).
Factory calibration can be specified in the purchase order. Also, if precision equipment, suitable
environment, and required skill are available at the user's site, input calibration can be done locally.
Reset Corrects
In some cases, the calibration procedure yields unsatisfactory results such that the Corrects constants must
be removed from memory. The Reset Corrects erases all three corrects constants, so that only the factory-
written characterization constants will be retained in the PROM.
Digital Communication Path
As indicated at key number (4) in Figure 4, the Honeywell Smart Transmitter includes a path for digital
communications between the sensor (via the microprocessor) and the 4-20 mA current loop that connects
the transmitter to external communications devices such as process control equipment ("receiver") and/or to
a MC Toolkit.
Digital to-Analog Conversion and Transfer
The digital-to-analog converter (D/A) shown at key number (5) in Figure 3 is shown as a box with a dotted
line to indicate that analog output mode is a user-selectable feature, for use in an application whose
receiving equipment requires an analog input.
Note that the Digital I/O (Comm) (communications) box is shown in Figure 3 with solid line to indicate
that the digital communications path is available at all times, even when analog mode is selected.
Honeywell Transmitter Output - Analog Mode
The diagram in Figure 4 provides an overview of a Honeywell transmitter operating in the analog mode.
Analog (PV Signal) Output
The vertical scale at the left of Figure 4 is an example of the available range (LRL to URL) of a pressure
transmitter sensor as built and characterized at the factory. The area of this scale that is highlighted in
white represents the configured process operating range (LRV to URV) - in this case, from 100 in H
2
O to
225 in H
2
O.
Note that Engineering Units (EUs) shown in Figure 4 are included here only for reference. The transmitter
does not perform any conversion of the base units value to Engineering Units. All conversion to EUs is
performed in the MC Toolkit and/or in other receiving devices such as operating panels associated with
control equipment. Default conversion is to inches-H2O @39F.)
The output of a Honeywell transmitter operating in the analog mode is a scaled value (0% - 100%) of
current (4 mA to 20 mA), whose lower and upper limits correspond to the configured operating range
(LRV-URV), respectively.
At the right of Figure 4, "PVEULO", "PV", and "PVEUHI" are examples of parameter names that appear
on Honeywell control equipment, which are used as follows.
Parameter Name
Parameter Description
Display Examples
PVEULO
Process Value , Engineering Units, Low
PVEULO 100 in H20
PV Process
Value
PV 175 in H20
PVEUHI
Process Value , Engineering Units, Low
PVEUHI 225 in H20
