Goodrive18 series two-in-one VFD Communication
-119-
return((unsigned char)(–((char)uchLRC)));
}
7.3 Command codes and communication data
7.3.1 RTU mode
7.3.1.1 Command code 03H (0000 0011), reading N words (continuously reading a
maximum of 16 words)
The command code 03H is used by the master to read data from the VFD. The count of data
to be read depends on the "data count" in the command. A maximum of 16 pieces of data can
be read. The addresses of the read parameters must be contiguous. Each piece of data
occupies 2 bytes, that is, one word. The command format is presented using the hexadecimal
system (a number followed by "H" indicates a hexadecimal value). One hexadecimal value
occupies one byte.
The 03H command is used to read information including the parameters and running status of
the VFD.
For example, to read two contiguous data content pieces from 0004H from the VFD with the
address of 01H (that is, to read content from data addresses 0004H and 0005H), the frame
structure is as follows:
RTU master command (from the master to
the VFD)
RTU slave response (from the VFD to the
master)
T1-T2-T3-T4 between START and END is to provide at least the time of 3.5 bytes as the
leisure time and distinguish two messages for the avoidance of taking two messages as one
message.
ADDR=01H means the command message is sent to the VFD with the address of 01H and
ADDR occupies one byte.
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