In-Situ Aqua TROLL 400 Modbus and SDI-12 Reference Guide - Manual (Page 40)

Register Size
(registers)
Mode & Access Level
(R/W)
Data
Type
Description
0567 2 R1/W3 float Off line sentinel value
(default = 0.0)
0569 1 R1 16 bits Available Units = 0x0001 (1)
Total Dissolved Solids
The default units for TDS are ppt. Conversion to other units is as follows.
ppm = ppt * 1000
TDS is calculated from specific conductivity using the following equation.
TDS = CF
TDS
* SC
Where CF
TDS
is the TDS conversion factor in ppm units as specified in the sensor calibration registers.
The default conversion factor is 0.65.
0570 2 R1 float Measured value, TDS
0572 1 R1 ushort Parameter ID = 13 (TDS)
0573 1 R1/W2 ushort Units ID
113 = parts per million
114 = parts per thousand
(default)
0574 1 R1 ushort Data Quality ID
0575 2 R1/W3 float Off line sentinel value
(default = 0.0)
0577 1 R1 16 bits Available Units = 0x0003 (3)
Resistivity
Resistivity is calculated from actual conductivity using the following equation.
R (ohm-cm) = 10
6
/ AC (uS/cm)
If the actual conductivity is zero, R is reported as 10,000,000 ohm-cm.
0578 2 R1 float Measured value, R
0580 1 R1 ushort Parameter ID = 11(resistivity)
0581 1 R1/W2 ushort Units ID 81 = ohm-cm (default)
0582 1 R1 ushort Data Quality ID
40