Xylem H-3342 - Manual (Page 12)

2-4 Installation
H-3342
adjustment screw clock-wise to increase the Stage and counter-clock wise to decrease the Stage.
Turning the adjust screw slowly will change the hundredths digit while turning the screw fast
changes the tenths digit. This allows one control to make both fine and course adjustments.
Alternatively, an extended SDI-12 command is convenient to quickly set the H-3342's Stage
reading to match the current water level. The “aXSCSdd.d!” command causes the H-3342 to
make a fresh measurement and automatically update the Offset as needed to produce the desired
Stage. See Chapter 3 for details.
Example of a H-3342 Extended "Set Current Stage" command:
Command
Response Time Values Description
"aXSCS2.3!" "a0021" 2 sec 1 Set the Stage to 2.3
Subsequent Command Response Description
"aD0" a+12.80 The new Offset
2.7 Programming the 4-20mA Output
The H-3342 scales the current Stage data to drive the 4-20mA output. The 4-20mA_Hi and 4-
20mA_Lo settings control how the Stage data is processed. The 4-20mA_Lo should be set to the
desired Stage corresponding a 4.00mA output. The 4-20mA_Hi should be set to the desired Stage
corresponding to a 20.00mA output. For testing purposes, the H-3342 comes from the factory
with 4-20mA_Hi = 20.0 and 4-20mA_Lo = 4.00. See Chapter 3 for details on programming these
settings.
The extended “aXS!” command allows convenient testing of the 4-20mA output. This command
allows the user to temporarily force the Stage to a test value. For example, the user can force the
shaft position (Stage) to several different values while calibrating or monitoring the attached 4-
20mA instrumentation. Once a fresh measurement is made via a SDI-12 measurement or by
pressing the “Read” button, the temporary Stage data is overridden.
The 4-20mA output is updated whenever a measurement is made. If no measurements are made,
the 4-20mA output becomes “stale”. For industrial applications where the H-3342 is connected to
a SCADA or PLC system (or no data logger is employed) and low-power is not of concern, the
H-3342 can be programmed to make continuous measurements. See Chapter 3 for details. The H-
3342 comes from the factory with the power mode set to the Sleep mode.
2.8 Testing
After completing the installation, test the encoder by manually rotating the pulley. Press and
hold the “Read” button to observe the Stage data. Make certain the readout matches the expected
measurement.