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ii. Register List:
Registers:
Size:
The Register List controls what Modbus Registers are recorded in each record of the
Historical Log. Since many items, such as Voltage, Energy, etc., take up more than 1
register, multiple registers need to be listed to record those items.
For example: Registers 0x03E7 and 0x03E8 are programmed to be recorded by the
historical log. These registers program the log to record "Primary Readings Volts A-N."
Each unused register item should be set to 0x0000 or 0xFFFF to indicate that it
should be ignored.
The actual size of the record, and the number of items in the register list which are
used, is determined by the # registers in the header.
Each register item is the Modbus Address in the range of 0x0000 to 0xFFFF.
iii. Item Descriptor List:
Registers:
Size:
While the Register List describes what to log, the Item Descriptor List describes how to
interpret that information. Each descriptor describes a group of register items, and what
they mean.
Each descriptor is composed of 2 parts:
E
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Type: The data type of this descriptor, such as signed integer, IEEE floating
point, etc. This is the high nibble of the descriptor byte, with a value in the range
of 0-14. If this value is 0xFF, the descriptor should be ignored.
0
1
2
3
4
5
6
7-14
15
Size: The size in bytes of the item described. This number is used to determine
the pairing of descriptors with register items.
For example: If the first descriptor is 4 bytes, and the second descriptor is 2
bytes, then the first 2 register items belong to the 1
register item belongs to the 2
NOTE: As can be seen from the example, above, there is not a 1-to-1 relation
between the register list and the descriptor list. A single descriptor may refer to
multiple register items.
0x7919 – 0x798D
1 register per list item, 117 list items
0x798E – 0x79C8
1 byte per item, 117 bytes (59 registers)
ASCII: An ASCII string, or byte array
Bitmap: A collection of bit flags
Signed Integer: A 2's Complement integer
Float: An IEEE floating point
Energy: Special Signed Integer, where the value is
adjusted by the energy settings in the meter's
Programmable Settings.
Unsigned Integer
Signed Integer 0.1 scale: Special Signed Integer, where
the value is divided by 10 to give a 0.1 scale.
Unused
Disabled: used as end list marker.
nd
descriptor.
Doc# E149701
st
rd
descriptor, and the 3
B-6
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