F-74
6.30.2 Using the RS485 port fitted as standard
With the standard serial RS485, you can connect each inverter to a higher-order control system
(host computer) to set up a data communications network between inverters. Also, you can
establish a data communications link between a computer and each inverter.
Serial RS485 connectors should be used to connect inverters to one another.
■
Data transfer specification
Item
Specification
Interface
RS485
Transmission path
specification
Half-duplex transmission [2/4-wire, bus architecture (A terminator needs
to be attached at each end of the system.)]
Transmission distance
Up to 500 m (overall length of the cable)
Number of
connectable units
Up to 32 units (including a host computer)
Up to 32
Synchronization mode
Asynchronous transfer
Data transfer rate
Default setting: 9600 bps (parameter setting)
Selectable from among1200, 2400, 4800, 9600, 19200 and 38400 bps
Transmission character
ASCII code ... JIS X 0201 8-bit (ASCII)
Binary code ... Binary code, 8-bit fixed
Stop-bit length
Received by inverter: 1 bit, sent from inverter: 2 bits
Error detecting system
Parity: even/ odd/ non (parameter setting), check sum
Error correction function
Not provided
Response monitoring
Not provided
Transmission code
Sending: 11 bit, Reception: 12 bit(with parity)
Transmission waiting
time setting
Possible
Others
Action the inverter takes when an timeout occurs: tripping/alarm/no action
→
When alarm is selected, "
" blinks at the left end of the control panel.
When tripping is selected, "
" is displayed on the control panel.
■
An example of the connection of inverters linked to a computer
<
Selective communications
>
When an operation frequency reference is isued by the host computer to the inverter No.
(IG)
Ignore: Inverters take no action if their numbers do not agree with the number specified in the
command( they ignore data received and get ready to receive the next data.)
①
The host computer transmits data to inverters.
②
Each inverter receives data from the host computer and checks the number specified by the
computer against its number.
③
Only the inverter with the number that agrees with that specified by the computer decodes the
command and takes action according to it.
④
On completion of the action, the inverter returns the results of the action taken to the host computer,
with the inverter number added to this information.
⑤
In this case, the inverter No. 3 only operates according to the operation frequency command
given by the host computer to it across the network
.
Host computer
INV
No
.
29
INV
No
.
30
〜
〜
:
Wiring
:
Data
(
Host
→
Inverter
)
:
Return data
(
Inverter
→
Host
)
IG
IG
IG
IG
IG
INV
No
.
03
INV
No
.
02
INV
No
.
01
INV
No
.
00
☆
☆
☆
☆
☆
☆:
Use a terminal board, etc., to divide each cable into branches.