Honeywell STT850 SMARTLINE, User Manual

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Page 18
STT850 Temperature Transmitter User’s Manual
Revision 3
1.15. Startup
3.1.13 Overview
This section identifies typical start up tasks associated with several generic temperature measurement
applications. It also includes the procedure for running an optional analog output check.
3.1.14 Startup Tasks
After completing the installation and configuration tasks for a Transmitter, you are ready to start up the
process loop. Startup usually includes:

Setting initial resistance (RTD sensor types only)

Reading inputs and outputs

Applying process inputs to the transmitter.
You can also run an optional output check to
wring out an analog loop and check out individual
Process Variable (PV) outputs in Digitally Enhanced (DE) mode before startup.
The actual steps in a startup procedure vary based on the type of Transmitter and the measurement
application. In general, the procedures in this section are based on using Honeywell MC Toolkit, with
a HART or DE variant, to check the Transmitter input and output under static process conditions, and
make adjustments as required initiating full operation with the running process.
Note: Checks can be made using the optional three-button assembly, if your Transmitter is so
equipped. Operation with the three-button assembly is discussed in the “Operation” section of this
manual.
3.1.15 Output Check Procedures
The Output Check comprises the following procedures:

The Loop Test procedure checks for continuity and the condition of components in the output
current loop.

The Trim DAC Current procedure calibrates the output of the Digital-to-Analog converter for
minimum (0%) and maximum (100%) values of 4 mA and 20 mA, respectively. This
procedure is used for Transmitters operating online in analog mode to ensure proper
operation with associated circuit components (for example, wiring, power supply, control
equipment). Precision test equipment (an ammeter or a voltmeter in parallel with precision
resistor) is required for the Trim DAC Current procedure.

The Apply Values procedure uses actual Process Variable (PV) input levels for calibrating
the range of a Transmitter. The PV is carefully adjusted to stable minimum and maximum
levels, and the Lower Range Limit Value (LRV) and Upper Range Limit Value (URV) are
then set by commands from the MC Toolkit.
The Transmitter does not measure the given PV input or update the PV output while it
operates in the Output mode.