[Basic frame]
End
CRC
Data
Function code
Slave
address
Start
Time of
no data
Time of
no data
2 Byte
(in hexadecimal)
N Byte
(in hexadecimal)
1 Byte
(in hexadecimal)
1 Byte
(in hexadecimal)
Command message/normal response message
End
CRC
Function code
Slave
address
Start
Time of
no data
Time of
no data
2 Byte
(in hexadecimal)
1 Byte
(in hexadecimal)
1 Byte
(in hexadecimal)
Error response message
12-6.2 Message Formation
Various factors of the message are specified as below.
[Start / End]
In MOD-BUS (RTU) communication, the start and end of the frame is normally set to 3.5byte
time with "P142: TEXT completion judgment time" in the inverter.
Setting value of parameter P142 changes depending on communication speed.
[Slave addresses]
The setting range is 1 to 31. ("P136: Communication station No.") "0" is broadcast (full station
command). During broadcasting, no response message is sent back in relation to this command
message.
Function code is supported for the following eight codes.
"(Read Coils)",
"Read Discrete Inputs",
"Read Holding Registers",
"Read Input Registers",
"Write Single Coil",
"Write Single Register",
"Write Multiple Coil",
"Write Multiple Registers"
[Function code]
12-6.1 Message Frame
172
