Xylem SDI-12 Data Logger iRIS 220, iRIS 320, iRIS 350, iRIS 150, iRIS 300 - Manual (Page 69)

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5. Enter the multiplier to scale the value. For SDI-12 instruments, the multiplier is typically 1 as the
instrument itself provides an actual value in engineering units. Enter an offset if required and known
at this point. More often, this is set on site to calibrate the measurement to a known reference of
datum. In this case the offset can be set by using the LCD calibration screen. See Section 5.2.6.
6. The General configuration should now look like this.
7. Now select the “Logging” tab and set up the logging parameters. In this example we are measuring
averaged water level in metres so we need to set the logging multipler to 1000 to store the value as
an integer (mm). The logging rate is 15 minutes. Our hypothetical sensor generates an error value
of 999.99 if it develops a fault or is unable to take a measurement. Rather than have this cause a
spike in our data, we are choosing to reject values above our expected maximum of 20 metres. We
also want to capture the minimum or maximum values over the period, so we enable the logging of
these as well.
8. The Logging configuration should look like this.
9. Next select the “Alarms” tab. We are going to set a low level alarm at 3.5 metres and a high level
alarms at 17 metres. Both alarms will have a reset differential of 0.1 metres making the reset levels
3.6 metres and 16.9 metres respectively. The alarms are set to be immediately acting, so no
duration delay is required.
10. The Logging configuration should look like this.
Note that the entry for Sensor 1 on the sensor list will now have a red question mark (?) next
to it. This indicates that the configuration has been changed and has not yet been sent to the
iRIS and/or saved to disk.