In-Situ RDO PRO Process Optical Dissolved Oxygen Sensor Manual - Manual (Page 20)

6.4 Calibration Registers
Register Size
(registers)
Mode & Access Level
(R/W)
Data
Type
Description
0118 2 R1/W3 float Live salinity value (PSU)
0120 2 R1/W3 float Default salinity value (PSU, default = 0.0)
0122 2 R1/W3 float Live barometric pressure (mbar)
0124 2 R1/W3 float Default barometric pressure (mbar, default = 1013.25)
0126 2 R1/W3 float 100% saturation calibration reading (mg/L)
0128 2 R1/W3 float 100% saturation temperature reading (°C)
0130 2 R1/W3 float 100% saturation salinity value (PSU)
0132 2 R1/W3 float 100% saturation barometric pressure (mbar)
0134 2 R1/W3 float 0% saturation calibration reading (mg/L)
0136 2 R1/W3 float 0% saturation temperature reading (°C)
0138 2 R1/W3 float Calibration slope (default = 1.0)
0140 2 R1/W3 float Calibration offset (default = 0.0)
Live Salinity Value
The live salinity value is used to correct the oxygen concentration value for salinity. Values must be
written in Practical Salinity Units (PSU) in the range 0 to 42 PSU. This is not a measured parameter.
Default Salinity Value
The default salinity value is loaded into the live salinity value register when power is first applied to
the probe. The default salinity value is used in calculations until a live salinity value is written. This is
not a measured parameter.
Live Barometric Pressure
The live barometric pressure is used in the calculation of percent saturation and to determine the
theoretical saturation point during calibration. Values must be written in millibars in the range
506.625 to 1114.675 mbar. This is not a measured parameter.
Default Barometric Pressure
The default barometric pressure is loaded into the live barometric pressure register when power is
applied to the probe. The default barometric pressure is used in calculations until a live barometric
pressure is written. This is not a measured parameter.
100% Saturation Calibration Values
These values represent the sensor conditions while the probe is in a 100% saturation calibration
environment. These are not measured values, they are written by the controller during the calibration
process.
Writes to these registers are only accepted if the probe is in the calibration mode. The probe will
return exception 0x85 (invalid device command sequence) if an attempt is made to write these
registers when the calibration mode is off.
Page 20 Modbus Registers