User Manual of A90 Series Inverter
274
command without saving.
42
C2
This function code is used to write multiple registers or
commands without saving.
08
88
This function code is used for diagnosis.
06
86
This function code is used to write a single register or
command.
10
90
This function code is used to write multiple registers or
commands.
PDU parts are detailed in the following sections, depending on various functions.
12.3.3.1 0x03: function code used to read multiple registers or status words
In the remote terminal unit, this function code is used to read the content in the
continuous block of the holding register. The request PDU describes the starting register
address and the number of registers.
The register data in the response message is divided into two bytes in each register.
The first byte of each register includes high-order bits and the second byte includes
low-order bits.
Request PDU
Function code
1 byte
0x03
Starting Address
2 bytes
0x0000 - 0xFFFF
Number of registers
2 bytes
1 - 16
Response PDU
Function code
1 byte
0x03
Number of bytes
1 byte
2×N*
Register value
N*×2 bytes
N* = number of registers
Error PDU
Error code
1 byte
0x83
Exception code
1 byte
01, 02, 03 or 04
Below is an example of a request to read the registers F19.00 to F19.05 (relevant
