INSTALLATION GUIDE
MODULAR SUNWAY TG
TE OD
Rev. 03
– 01/06/2018
77/
139
2.6 V between line A (D1) and 0 V
2.4 V between line B (D0) and 0 V
WARNING
If the COM1 is used as a Master port for the PV field trunk lines to the Smart String Boxes,
manually program the Data Logger board routing table on COM1. Please refer to the Data
Logger Programming Guide.
7.3.
Connection
7.3.1. RS-485 bus
– main principles
The MODBUS-IDA organization (
http://www.modbus.org
) defines the connection for Modbus
communication on RS485 serial link (used by the inverter) as 2-wire cable type. For this type of cable, the
following specifications are recommended:
Connection cable
Type of cable
Shielded cable made up of a balanced pair known as D1/D0 + common
conductor. Recommended cable: Belden 3106A Paired EIA Industrial
RS485 PLTC/CM.
Minimum
cross-section
for conductors
AWG23 corresponding to 0.258 mm
2
. For long lengths it is advisable to use
a larger section, up to 0.75 mm
2
.
Maximum length
500 metres with reference to the maximum distance measured between the
two stations furthest apart.
Impedance
specifications
Recommended over 100 Ω, usually 120 Ω.
Table 20: Connection cable
It is advisable to connect all the equipment connected to the multidrop connection network to the earth by
means of a common conductor. In this way, any differences in earth potential between different equipment
which may interfere with communications is reduced to a minimum.
The common terminal 0V connection is necessary. An 0V connection which is common to all equipment in
the multidrop communication network minimizes possible differences of reference potential between the
equipment which could interfere with communication.
The common reference of control board power supply is isolated in relation to earth. By connecting one or
more inverters to a communication device with a common earth (for example a PC) a low-impedance path
between the control board and earth is obtained. It is possible that disturbances conducted at high frequency
from the power parts of the inverter may transit along this path and this can cause malfunctions to the
communication apparatus.
It is always advisable to equip the communication equipment with a galvanically isolated RS485
communication interface or a galvanically isolated RS485/USB convertor.
WARNING
Cat. 5 2-, 3- or 4-pair data transmission cables cannot be used for the serial connection,
not even over short sections.
Wiring operations of the module must be carried out when the inverter is NOT powered.
Remember to take all the necessary precautions before accessing the connectors and
before handling the board.
