Goodrive350-19 series VFD Communication protocols
- 439 -
whether it is a normal response (no error) or exception response (some errors occur). In a normal
response, the device returns the corresponding function code and data address or sub-function code.
In an exception response, the device returns a code that is equal to a normal code, but the first bit is
logic 1.
For example, if the master device transmits a request message to a slave device for reading a group
of function code address data, the code is generated as follows:
0 0 0 0 0 0 1 1 (03H in the hexadecimal form)
For a normal response, the same code is returned.
For an exception response, the following code is returned:
1 0 0 0 0 0 1 1 (83H in the hexadecimal form)
In addition to the modification of the code, the slave returns a byte of exception code that describes
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:
VFD
address
Write
command
Parameter
address
Parameter
data
CRC
01
06
00 01
00 03
98 0B
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:
VFD
address
CRC
Error code
Exception
response code
01
86
04
43 A3
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".
10.4.8 Read/Write operation example
For the formats of the read and write commands, see sections 10.4.1 and 10.4.2.
10.4.8.1 Read command 03H examples
Example 1: Read status word 1 of the VFD whose address is 01H. From the table of other function
parameters, we can see that the parameter address of status word 1 of the VFD is 2100H.
The read command transmitted to the VFD is as follows:
