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V: 1.00 Revised: Jan 2021
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AcuRev 2100 Series Power Meter: Web Manual
d. Data Field
The data eld is constructed using sets of two hexadecimal digits, in the range of 00 to FF. The
data eld of messages sent from a master to a slave contains additional information that the
slave must use to take the action dened by the function code. This can include information
such as the register addresses, the number of registers to query and the count of the actual
number of data bytes. For example, if the master requests a slave to read a group of holding
registers (function code 03), the data field specifies the starting register and how many
registers are to be read.
If the master needs to write data (function code 10 hexadecimal) to a group of registers in the
slave, the data eld species the starting register, how many registers to write, the count of
data bytes to follow in the data eld and the data to be written into the registers.
5.4.2 Format of Communication
Explanation of frame
Transaction
identier hi
Transaction
identier lo
Protocol
identier hi
Protocol
identier lo
Length hi Length lo
Unit
identier
00H 00H 00H 00H 00H 06H 01H
Function Code Data start register hi Data start register lo Data # of registers hi Data # of registers lo
03H 40H 00H 00H 48H
The meaning of each abbreviated eld above is:
Transaction identier hi: High byte of the transaction identier
Transaction identier lo: Low byte of the transaction identier
Protocol identier hi: High byte of the protocol identier
Protocol identier low: Low byte of the protocol identier
Length hi: High byte of length
Length lo: Low byte of length
Unit identier: Slave address
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