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Modbus Protocol
11.3.1 Data dictionary
The following tables detail the Modbus addresses required to access each item of the
public data.
Addressing (0 or 1 Based)
The addressing within the Modbus/TCP protocol (that is, the data within the physical
packet) is 0-based, meaning the first element/item to be accessed is referenced by
address 0. The Modbus standard for handling and displaying the data is 1-based;
meaning the first element/data item to be access is referenced by address 1.
Most client applications handle this by having the user enter the 1-based number, and
then subtract 1 to revert to the 0-based addressing required at the protocol level.
Some client applications allow the user to enter the 0-based number, or a combination,
depending on how it is configured.
The addresses defined within the following table are 1-based, as the majority of the client
applications work with this method.
Identification Block
The Identification Block registers consists of basic information about the instrument.
These registers are read-only and are updated by the instrument during the initial
power-on sequence. In addition, these registers are only configurable at the factory and
by qualified field service personnel.
Note: Use FC16 where '*' is indicated.
Address 0-14 (Manufacturer Identification) (Format: Strings)
Get the instrument's Manufacturer ID. The ID consists of 30 bytes of printable ASCII
characters (0x20-0x7E). A register byte value of 0x00 or word value of 0x0000 indicates
the end of the Manufacturer ID.
Address 15-24 (Model Number) (Format: Strings)
Get the model number. The model number consists of 20 bytes of printable ASCII
characters (0x20-0x7E). A register byte value of 0x00 or word value of 0x0000 indicates
the end of the model description.
Identification Block
Address Register Description Access
Size
(Words)
0000 Manufacturer ID R 15
0015 Model Number R 10
0025 Serial Number R 5
0030 Secondary ID R 4
0034 Last Calibration Date R 2
0036 Calibration Due Date R 2
0038 Firmware Version R 1
0039 Hardware Version R 1
0040-0099 Future Expansion
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