Goodrive10 Series Mini VFD Communication protocol
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7.3.5 Fieldbus ratio scale
In practical applications, communication data is represented in the hexadecimal form, but
hexadecimal values cannot represent decimals. For example, 50.12Hz cannot be
represented in the hexadecimal form. In such cases, we can multiply 50.12 by 100 to obtain
an integer 5012, and then 50.12 can be represented as 1394H (5012 in the decimal form) in
the hexadecimal form.
In the process of multiplying a non-integer by a multiple to obtain an integer, the multiple is
referred to as a fieldbus scale.
The fieldbus scale depends on the number of decimals in the value specified in
"Description" or "Default ". If there are n decimals in the value, the fieldbus scale m is the
n
th
-power of 10. Take the following table as an example, m is 10.
0.0–3600.0s (valid when
P01.19=2)
The value specified in "Setting range" or "Default" contains one decimal, so the fieldbus
scale is 10. If the value received by the upper computer is 50, the value of
"Wake-up-from-sleep delay" of the VFD is 5.0 (5.0=50/10).
To set the "Wake-up-from-sleep delay" to 5.0s through Modbus communication, you need
first to multiply 5.0 by 10 according to the scale to obtain an integer 50, that is, 32H in the
hexadecimal form, and then transmit the following write command:
VFD
address
Write
command
Parameters
address
Data number CRC check
After receiving the command, the VFD converts 50 into 5.0 based on the fieldbus scale, and
then sets "Wake-up-from-sleep delay" to 5.0s.
For another example, after the upper computer transmits the "Wake-up-from-sleep
delay"parameter command, the master receives the following response from the VFD:
VFD
address
Read
command
Parameter
data
CRC check
2-byte
data
01 03 02 00 32 39 91
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