GU320a Controller Manual
17
The controller with RS485 communication interface, which allows connect at least 255 same serial
controllers to the same communication line. And each equipment has sole ID No. To switch PC or MODEM,
you need to collocate another RS485/RS232 converter. Typical wiring diagram as below：
Note
：
Communication cable use high quality twisted pair cable with shielded, and its total length of
cable less than 1000m. Each anode and cathode of RS485 interface must be connected properly, and the
cable shield only can be connected to the earth at one side.
GU320a Controller
(DB9)
RS CONNECTOR
CI485A
A
B
S
Computer
GU320a Controller
RS CONNECTOR
(DB9)
CI485A
GU320a Controller
RS CONNECTOR
(DB9)
CI485A
MODEM
A
转换器
RS485/232
B
S
Able to connect respectively
A
B
S
B
A
S
R connect to risister
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