Output Check Procedures; Constant Current Source Mode Procedure; Figure 16 - Current Loop Test Connections - Honeywell SmartLine ST 800 User Manual

3.7.3 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. To measure a liquid level for example, a sight-glass can be used to
determine the minimum (0%) and maximum (100%) level in a vessel. 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 HVC.
The transmitter does not measure the given PV input or update the PV output while it
operates in the Output mode.

3.7.4 Constant Current Source Mode Procedure

1. Refer to Figure 16
only. Verify the integrity of electrical components in the output current loop.
2. Establish communication with the transmitter. For these procedures, the values of components in the
current loop are not critical if they support reliable communication between the transmitter and the
Configurator.
20
Figure 16 – Current Loop Test Connections
for test connections using the HVC. The device shown is for illustrative purposes
ST 800 Pressure Transmitter User's Manual
Revision 15