INVT GD350A-004G/5R5P-4, Руководство по эксплуатации

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Goodrive350A series high-performance multifunction VFD Communication
-331-
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
n
th
-power of 10. Take the following table as an example, m is 10.
Function
code
Name Description
Setting
range
Default Modify
P01.20
Wake-up-from-sleep
delay
0.0
–3600.0s
(valid
when P01.19 is 2)
0.00
–3600.0
0.0s
○
P01.21
Restart after power
failure
0: Disable
1: Enable
0
–1
0
○
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
Parameter
address
Parameter
data
CRC
01 06 01 14 00 32 49 E7
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:
VFD
address
Read
command
Parameter
data
CRC
2-byte
data
01 03 02 00 32 39 91
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.