Unitronics UMI-B1 UL Series - Page 113

UMI-B1 UL Series Inverter Communication protocol
111
Twisted pairs with shied screen
Earth
Earth
Computer
RS485 Rout
Convert from
RS232 to RS485
485- 485+
Inverter
Figure 7-1 RS485 physical connection in single application
7.2.1.2 Multi-applications
In real multi-applications, the chrysanthemum connection is used.
Chrysanthemum chain connection is required in the RS485 industrial fieldbus standards.
The two ends are connected to terminal resistors of 120Ω, as shown in Figure 7-2.
inverter
Address 1
inverter inverter
Earth
485+
485-
Earth
485+
485-
Earth
485+
485-
120Ω
Terminal resistor
Computer
Converter
GND
RS232–485
Max. length of RS:
15m
Shielded twist pairs
Address 2
Address N
Figure 7-2 Chrysanthemum connection applications
It is recommended that you use shield cables when multiple devices are connected. The
basic parameters of the devices, such as baud rate and digital check bit in RS485
should be the same and there should be no repeated address.