Read/Write Operation Example - INVT Goodrive350 Series Operation Manual

Goodrive350 series high-performance multifunction VFD
the cause of the exception. After receiving the exception response, the typical processing of the
master device is to transmit the request message again or modify the command based on the fault
information.
For example, to set the "Running command channel" (P00.01, the parameter address is 0001H) of
the VFD whose address is 01H to 03, the command is as follows:
01
VFD
address
But the setting range of the "Running command channel" is 0 to 2. The value 3 exceeds the setting
range. In this case, the VFD returns an error message response as shown in the following:
01
VFD
address
The exception response code 86H (generated based on the MSB "1" of the write command 06H)
indicates that it is an exception response to the write command (06H). The error code is 04H. From
the preceding table, we can see that it indicates the error "Operation failure", which means "The
parameter is set to an invalid value in the write operation".

9.4.8 Read/Write operation example

For the formats of the read and write commands, see sections 9.4.1 and 9.4.2.
9.4.8.1 Read command 03H examples
Example 1: Read state word 1 of the VFD whose address is 01H. According to the table of other
Modbus function addresses, the parameter address of state word 1 of the VFD is 2100H.
The read command transmitted to the VFD is as follows:
01
VFD
address
Assume that the following response is returned:
01
VFD
address
The data content returned by the VFD is 0003H, which indicates that the VFD is in the stopped state.
Example 2: View information about the VFD whose address is 03H, including "Type of current fault"
(P07.27) to "Type of 5th-last fault" (P07.32) of which the parameter addresses are 071BH to 0720H
(contiguous 6 parameter addresses starting from 071BH).
The command transmitted to the VFD is as follows:
06 00 01
Write Parameter
command address
86
Exception
response code
03 21 00
Parameter
Read
address
command
03
Read
command
00 03
Parameter
data
04
Error code
00 01
Data quantity
02 00 03
Number
Data content
of bytes
-281-
Communication
98 0B
CRC
43 A3
CRC
8E 36
CRC
F8 45
CRC