Data Formats - Thermo Scientific AquaSensors RDO Pro-X Manual

Thermo Scientific AquaSensors
Note: Registers 48580-48589 and 49000-49199 are reserved for factory use.

Data Formats

The Modbus protocol defines 8-bit byte and 16-bit register fields within messages and
commands; however, it does not define the format of more complex data types. Defined below
are the data types used by the probe. All multiple register formats must be read or written within
a single command.
Type Registers Bytes
BYTE -- 1
SHORT 1 2
USHORT 1 2
LONG 2 4
ULONG 2 4
FLOAT 2 4
STRING N 2 * N
All data types in this section are shown in the default big endian format (most significant byte
first). The byte order within the registers of the FLOAT data type may be changed by writing to
the PLC Data Type register.
Byte
An 8-bit unsigned integer contained in a single byte. Used within command and response
messages. Not used as a register format.
XXXX XXXX
MSB
Byte 0
Short
A 16-bit two's-complement signed integer contained in a single register data address.
SXXX XXXX
MSB
Byte 0
Where: 'S' = sign bit.
Description
8-bit unsigned integer
16-bit 2's-complement signed integer
16-bit unsigned integer
32-bit 2's-complement signed integer
32-bit unsigned integer
32-bit IEEE floating-point value
2 * N consecutive characters
LSB
XXXX XXXX
LSB
Byte 1
RDO Pro-X Optical Dissolved Oxygen Measurement System
Modbus Register Map Section 8
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