Contents
1.0 Introduction ........................................................................................................................... 3
2.0 Safety Instructions ................................................................................................................. 3
3.0 Hazardous Products ............................................................................................................... 3
4.0 GENERAL ................................................................................................................................ 3
5.0 Action on Receipt ................................................................................................................... 4
6.0 Installation ............................................................................................................................ 4
6.1 Lowering the Pressure Probe ......................................................................................... 4
6.2 Electrical Installation ..................................................................................................... 5
7.0 Operation ............................................................................................................................... 6
7.1 Analogue Output Probes ............................................................................................... 6
7.2 SDI12 Operation ............................................................................................................ 6
8. Maintenance ............................................................................................................................ 9
8.1 Self diagnostics ............................................................................................................. 9
8.2 Calibration Adjustment ............................................................................................... 10
8.3 Cleaning ...................................................................................................................... 14
9. Advanced Operation ............................................................................................................... 14
10. WARRANTY ......................................................................................................................... 16
11. Servicing ............................................................................................................................ 16
12. Return to Factory ................................................................................................................ 16
To re-range the 595 sensor proceed as follows:
1. Determine the 595 sensor full scale and the user application full scale.
2. Find the required calibration gain. Divide the 595 sensor full scale by the user
application full scale (e.g. 10/4)
3. Program the calibration gain into the sensor (via SDI12 interface).
(e.g. aXG2,2.5!)
4. Check the residual error with zero pressure applied. Note as the gain is in-
creased any offset errors ban be magnified. So for example instead of 4mA
expected sensor reads 3.959mA.
5. Program offset in calibration of sensor to remove offset errors (e.g. aXA2,0.041!)
6. Save new calibration to nonvolatile memory (e.g. aXS0!)
7 Verify sensor now measures 4 to 20mA for required application range.
Configure a Reverse Output 20mA to 4mA.
If your application demands a 20mA output with zero applied pressure and 4mA
output for full scale applied pressure then the sensor output can be reversed by
sending the following SDI12 commands:
1.
Set calibration gain of mA output to -1 (e.g. aXG2,-1!)
2.
Set calibration offset of mA output to +24 (e.g. aXZ2,24!)
3.
Save new calibration to nonvolatile memory (e.g. aXS0!)
4.
Verify sensor now measures 20mA to 4mA for 0 to full scale applied
pressure.
Applying a Filter to the mA Output
In applications that are inherently difficult to measure, for example waves on
reservoir, then the 595 can be configured to apply a mean or median filter via the
SDI12 interface before updating the analogue mA output. The filter command is
described below:
SDI12 Command:
0XFt,nn,xxxx!
Neptune Response:
0t,nn,xxxx<CR><LF>
Where:
T = type of filter
0 = MEAN
1 = MEDIAN
nn = number of values to filter, maximum 12
xxxx = 220ms intervals between measurements, maximum period 1
hour
To apply a filter:
1. Determine the type of filter and period suitable for the application.
2. Send the filter command to the 595 sensor (e.g. 12 reading mean, sampling
period 15 minutes, aXFt,12,4091A)
3. Save the filter to nonvolatile memory (e.g. aXS0!)
4. Verify the filter performance in applications.