ABB A43, Руководство пользователя

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Communication with Modbus
A43/A44 106
2CMC48001M0201
User Manual Revision: C
9.3 Reading and Writing to Registers
Readable The readable range in the modbus mapping are registers 1000-8EFF
registers
(hexadecimal). Reading any registers within this range will result in a normal
Modbus response. It is possible to read any number of registers between 1 and
125, i.e., it is not necessary to read all registers of a quantity listed on one line in
the mapping tables. Any attempt to read outside this range will result in an illegal
data address exception (Modbus exception code 2).
Multi-register
values
Unused registers
Writing to
registers
For quantities that are represented as more than 1 register, the most significant
byte is found in the high byte of the first (lowest) register. The least significant
byte is found in the low byte of the last (highest) register.
Unused registers within the mapping range, for example missing quantities in
the connected meter, will result in a normal Modbus response but the value of
the register will be set to “invalid”.
For quantities with data type “unsigned”, the value will be FFFF in all
registers. For quantities with data type “signed”, the value is the highest value
possible to express. That means that a quantity that is represented by only one
register will have the value 7FFF. A quantity that is represented by 2 registers
will have the value 7FFFFFFF, and so on.
Writing to registers is only permitted to the registers listed as writable in the
mapping tables. Attempting to write to a register that is listed as writable but
that is not supported by the meter will not result in an error indication.
Note
–
It is not possible to modify parts of a setting, e.g. to set only the year and
month of the Date/time setting.
Confirm set
After you set a value in the meter, it is recommended that you read the value to
values
confirm the result, since it is not possible to confirm if a write was successful from
the Modbus response.