3 rs485 communication, Use the gland fitting with one hole – SMA SB 2800i Installation User Manual

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Communication

Installation Guide

SMA Regelsysteme GmbH

SB2800i-11:SE0504

7.3 RS485 Communication

RS485 is a communication standard for up to 50 Sunny Boy
inverters with a total cable length of up to 1200 m. The following
conditions must be fulfilled for RS485 communication:

• All Sunny Boys have to be equipped with the second cable

gland (included in delivery) on their underside.

• All Sunny Boys have to be equipped with an

RS485 Piggy-Back.

• A cable with common shield (such as LiYCY) with two twisted

pair with a line impedance of 100 ohm.

• The first and the last participant of the RS485 bus have to be

equipped with a termination resistor.

• The ordering code for the RS485 is 485PB-NR

At the moment the Sunny Boy Control and the Sunny
Boy Control Plus can communicate with PV-plants
with up to 5 different types and all in all 50 Sunny

Boy inverters in total. The Sunny Boy Control Light can
communicate with 5 different Sunny Boy types and all in all 20
Sunny Boy inverters in total.

To provide for an RS485 interface the Sunny Boy 2800i has to be
equipped with the second cable gland included in delivery. The
delivery includes two different gland fittings (a fitting with one
hole for one cable and a fitting with two holes for two cables).

Best start with the last Sunny Boy 2800i in the communication
chain (i. e. the one at the end of the RS485 cable):

1. Use the gland fitting with one hole.

2. Now attach one of the two plug connectors delivered to the

data cable. Connect the wires of one twisted pair to termi-
nals 2 and 7 on the communication slot (see Fig. 7.2: "One
or several Sunny Boys connected with an RS485 cable to a
PC with interface converter." (p. 30)). Write down which
wire is connected to which terminal!

3. Connect one (or both) wires of the second twisted pair to ter-

minal 5 on the communication slot. Write down which
wire(s) you have used!

4. If no other inverters have to be connected,

continue with point 8.

5. Now connect the next inverter. Use the contact

units with two holes.