Message Categories - Fuji Electric FRENIC-AQUA series User Manual

3.1.4

Message categories

There are eight RTU message categories; read holding registers, preset single register, preset
multiple registers, diagnostics, read coil status, force single coil, force multiple coils and error
response.
Each category is described below:
[ 1 ] Read holding registers
Query
1 byte 1 byte
Station
03
H
address
Normal response
1 byte 1 byte
Station
03
H
address
How to set a query
- This request is not available for broadcast transactions. Station address 0 will become
invalid (no response).
- 'FC' = 3 (03 )
H
- The function code is two bytes long. The Hi byte indicates the function code group (see Table
3.2), and the Lo byte represents a function code identification number (0 to 99).
(Example) When the function code is E15, the Hi byte is 01
- Each function code of the inverter is assigned to the holding register areas (40000 to 49999).
The address of each function code can be calculated with the following expression. (The
same applies also to "presetting single register" and "presetting multiple registers.")
Address calculation expression
40000 + (Code in Table 3.2) x 256 + Function code number
(Example) In the case of J60
J
↓
13
The holding register address of function code J60 =
40000 + (Code in Table 3.2: 13) x 256 + Function code number 60 = 43388
2 bytes 2 bytes
Number of read
Function code
data
Hi Lo Hi
1 byte
Byte count
Hi, Lo (data 0); Hi, Lo (data 1); ·····
60
↓
60
3-4
2 bytes
Error check
Lo
2 to 100 bytes
Read data
and the Lo byte is 0F
H
2 bytes
Error check
.
H