INVT Goodrive350A Series Operation Manual page 336

Goodrive350A series high-performance multifunction VFD
9.4.6 Fieldbus scale
In practical applications, communication data is represented in the hexadecimal form, but
hexadecimal values cannot represent decimals. For example, 50.12 Hz 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 "Detailed parameter
description" or "Default value". If there are n decimals in the value, the fieldbus scale m is the
th
n -power of 10. Take the following table as an example, m is 10.
Function
code
Wake-up-from-sleep
P01.20
Restart after power
P01.21
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:
01
VFD
address
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
read command, the master receives the following response from the VFD:
01
VFD
address
The parameter data is 0032H, that is, 50, so 5.0 is obtained based on the fieldbus scale (50/10=5.0).
In this case, the master identifies that the "Wake-up-from-sleep delay" is 5.0s.
Name
0.0–3600.0s
delay when P01.19 is 2)
0: Disable
failure 1: Enable
06 01 14 00 32
Parameter
Write
command address
03 02
Read
2-byte
command
data
Description
(valid
Parameter
data
00 32
Parameter
data
-331-
Setting
Default
range
0.00–3600.0 0.0s
0–1 0
49 E7
CRC
39 91
CRC
Communication
Modify
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