6. Description of Parameters
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6
Figure 6-26 Use Modbus serial comms. to control frequency reference
F0-03
.
= 9
Fd-00
Fd-01
Function Code
Parameter Name
Baud rate
Data format symbol
Fd-02
Fd-03
Fd-04
Fd-05
Modbus protocol selection and
PROFIBUS-DP data frame
Local address
Response delay
Communication timeout
Keep the following parameter setting
in AC drive with that in host computer.
Extension Modbus
card
485+
485-
CGND
RS485
Wire host computer and
extension Modbus card that
has been inserted onto the
drive.
Host
computer
= 0
Serial comms.
Main
frequency
reference
.
.
= 1
= 8
When the AC drive is controlled via communication, host computer must send write
command to the AC drive. Here takes Modbus as an example to describe process of
giving RUN command via serial communication.
To set frequency reference to 10000, host computer sends write command 01 06 10 00
27 10 97 36 (hexadecimal). In the command,
Ɣ
01H (settable): AC drive address
Ɣ
06H: write command
Ɣ
1000H: frequency reference address
Ɣ
2710H: frequency reference (converted into decimal 10000)
Ɣ
9736H: CRC check
Master Command Slave Response
ADDR 01H ADDR 01H
CMD 06H CMD 06H
Parameter address high bits 10H Parameter address high bits 10H
Parameter address low bits 00H Parameter address low bits 00H
Data content high bits 27H Data content high bits 27H
Data content low bits 10H Data content low bits 10H
CRC high bits 97H CRC high bits 97H
CRC low bits 36H CRC low bits 36H
Note
Frequency reference range set via communication is -10000 to 10000,
corresponding to -100.00% to 100.00%.
Ɣ
-100.00% corresponds to negative max. frequency.
Ɣ
0.00% corresponds to min. frequency.
Ɣ
100.00% corresponds to max. frequency.
Suppose that F0-10 = 50 Hz, if frequency reference in the write command is
2710, converted into decimal 10000. The input frequency reference is 50 x
100% = 50 Hz.
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