Unitronics UMI-B1 UL Series Operation Manual page 113

UMI-B1 UL Series 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.
Shielded twist pairs
RS232–485
Converter
Max. length of RS:
GND
Computer
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.
Twisted pairs with shied screen
Earth
Convert from
RS232 to RS485
Computer
485+
485-
Earth
inverter
15m
Address 1
Figure 7-2 Chrysanthemum connection applications
RS485 Rout
485- 485+
Earth
Inverter
485+
485-
Earth
inverter
Address 2
111
Communication protocol
485+ 120Ω
Terminal resistor
485-
Earth
inverter
Address N