Serial interface
50
isoPV_D00024_02_M_XXEN/07.2018
7. Serial interface
7.1 RS-485 interface with BMS protocol
The RS-485 interface electrically isolated from the device electronics and the current
output serves as a physical transmission medium for the BMS protocol. If several isoPV
or other bus-capable devices are interconnected in a network via the BMS bus, the BMS
bus must be terminated at both ends with a 120 Ω resistor.
An RS-485 network that is not terminated, is likely to get instable and may result in mal-
functions. Only the first and the last device in one line may be terminated. Devices in
between must not be terminated with 120 Ω. Hence, stub feeders in the network must
not be terminated. The length of the stub feeders is restricted to 1 meter.
7.2 Topology RS-485 network
The optimum topology for the RS-485 network is a daisy-chain connection In this con-
nection, device 1 is connected to device 2, device 2 to device 3, device 3 to device n etc..
The RS-485 network represents a continuous path without branches.
A
B
A
B
A
B
1st device
... device
last device
120
W
0.4 W
120
W
0.4 W
Stub feeder
maximum 1 m
Maximum length of the RS485 bus: 1200 m
Summary of Contents for ISOMETER isoPV with AGH-PV
Page 45: ...Operation and setting 45 isoPV_D00024_02_M_XXEN 07 2018 6 5 8 Diagram ISO ADVANCED ...
Page 47: ...Operation and setting 47 isoPV_D00024_02_M_XXEN 07 2018 6 6 4 Diagram COM SETUP ...
Page 57: ...57 isoPV_D00024_02_M_XXEN 07 2018 ...
Page 58: ...Coupled PV generators application example 58 isoPV_D00024_02_M_XXEN 07 2018 ...
Page 71: ......
