Xylem H-3531 FlashLite - Manual (Page 21)

H-3531
Installation 2-9
to the above screen image. When the user sets the stage the H-3531 FlashLite™ to make a
fresh measurement and automatically updates the Offset as needed to produce the desired
Stage. To set the stage using the RS-232 menu press ‘S’ for “S - Stage:” and enter in the
current stage value and then press enter. Then press the ‘M’ key for “M - Measure” and
verify that the set stage command did execute. You should see that the offset value has
changed. The other way to set the stage is to send the extended SDI-12 “Set Current
Stage” command. The “aXSCSdd.d!” command is discussed in more detail in chapter 5.
Example of a H-3531 FlashLite™ Extended "Set Current Stage" command:
Command
Response Time Values Description
"aXSCS2.3!" "a0061" 6sec 1 Set the Stage to 2.3
Subsequent Command Response Description
"aD0" a+12.80 The new Offset
2.8.2 0-5V Analog Output
The H-3531 FlashLite™ has a 12-bit digital-to-analog converter (DAC) and a precision
voltage reference. The Stage is scaled into a 12-bit value and loaded into the digital-to-
analog converter. The 0-5V analog output is updated whenever a measurement is made. If
no measurements are made, the 0-5V analog output becomes “stale”. For industrial
applications where the H-3531 FlashLite™ is connected to a SCADA or PLC system
instead of a SDI-12 data logger, the H-3531 FlashLite™ can be programmed to
automatically make continuous measurements. To program the H-3531 FlashLite™ to
make continuous measurements, issue an extended SDI-12 command and set
Power_Mode=3 or use the RS-232 menu interface. See chapter 4 and 5 for details. This
setting can be made at the factory if requested.
Note: When the H-3531 FlashLite™ is first powered up and the 0-5V analog output is
enabled, the output voltage is set to 0 volts. It remains at 0 volts until the first
measurement sequence.
2.8.2.1 Programming the 0-5V Output Range
The H-3531 FlashLite™ scales the current Stage data to drive the 0-5V analog
output. The 0-5V_Hi and 0-5V_Lo settings control how the Stage data is processed.
The 0-5V_Lo should be set to the desired Stage corresponding to a 0.00 volt
output. The 0-5V_Hi should be set to the desired Stage corresponding to a 5.00 volt
output. See chapter 4 and 5 for details on programming these settings.
2.8.3 4-20mA Output(Industrial Mode Only)
The H-3531 FlashLite™ has a 12-bit digital-to-analog converter (DAC), precision voltage
reference and a 4-20mA current transmitter. The SDI-12 and 4-20mA sections are isolated
from each other with a high voltage digital opto-coupler. The Stage is scaled into a 12-bit