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5.5
User Values for Derived Parameters
Several values reported by the probe are dependent upon parameters that the probe does not supply. It is, therefore, a
requirement of the user to supply these values if the derived parameters are of interest.
Salinity
Salinity values are not required (or available to be set) for ODO/CT probes, as the parameter value is already available. In ODO/T
probes, salinity is required for ODO mg/L calculations. The salinity value is set by writing an entire block of values (non-divisible)
using a write multiple registers command (function code 0x10). This information can be broadcast to all devices on the network and
updated periodically. The default on power-up is 0.0.
Address
Description
0x0400
User Salinity Value (ppt) [3:0]
0x0401
Request
Function Code
Register Address
Number Registers
Byte Count
Register Values
Water Pressure
In ODO/CT probes, water pressure is required for salinity calculations. The water pressure value is set by writing an entire block
of values (non-divisible) using a write multiple registers command (function code 0x10). This information can be broadcast to all
devices on the network and updated periodically. The default on power-up is 0.0.
Address
Description
0x0402
User Water Pressure Value (psi) [3:0]
0x0403
Request
Function Code
Register Address
Number Registers
Byte Count
Register Values
Modbus Configuration & Commands
1 byte
2 bytes
2 bytes
1 byte
4 bytes
1 byte
2 bytes
2 bytes
1 byte
4 bytes
0x10
0x0400
0x0002
0x04
User Salinity Value (ppt) [3:0]
0x10
0x0402
0x0002
0x04
User Pressure Value (psi) [3:0]
26
R/W
Type
Default
RW
Float
0.0
R/W
Type
Default
RW
Float
0.0
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