64
APPENDIX
B
Serial Communications
The different AC motor drive parameters can be programmed and displayed by remote control
via the RS-485 serial interface. A personal computer may be used to load, change, or monitor
the parameter value through the PC
‘
s RS-485 interface, which permits communication with
higher-level automation systems. This appendix describes the following:
Computer Control
Data Format and Protocol
Character Delay Time and Response Delay Time
Computer
Control
The VFD-A series AC motor drive has a built in RS-485 serial communication port on its control
terminal block marked SG+, SG-. The two connector pins are defined as follows:
SG
＋
: Signal
＋
SG
－
: Signal
－
Each VFD-A AC motor drive has a pre-assigned slave address specified by Pr.-78. The computer
may select any AC drive according to this slave address. The computer may also control all of the
AC drives connected to it when the
“
A
”
code in command string is 02H.
Data Format and Protocol
Data Format
Baud Rate (Transmission speed in bits per second)
Range of values: 1200, 2400, 4800 Baud (See Pr.-77)
Eleven (11) bits are required to represent each character, as shown in the following
example:
Number of bits
Function
1
start bit
8
data bits
1
odd parity bit
1
stop bit
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sales@deltaacdrives.com
