SMA America, LLC Electrical connection
Installation Guide SB30-40US-IUS103030 57
6.8.1 RS485 communication
RS485 is a communication standard for bidirectional transmission of data between one or more
Sunny Boy inverters and a PC.
All Sunny Boy inverters are capable of RS485 communication. You can mix different Sunny Boy
models on the RS485 communication bus.
For more information on connecting more than one inverter to an RS485 bus, please see “Technical
Note: RS485 Communication” in the Technical Information section under Service Downloads of our
web site at www.SMA-America.com.
Requirements for RS485 communication
• The Sunny Boy must be equipped with an RS485 Piggy-Back communication module.
• The cable should be no longer than a
3
⁄
4
mile (1.2km) with a common shield, and a wire size
no smaller than 24 AWG. Use the cable type specified in the RS485 Tech Note on
www.SMA‑America.com.
• RS485 cables are available from SMA America.
• Conduit may be required for communication wiring, per local electrical code requirements.
Connecting a RS485 cable
1. Connect the three wires of the RS485 cable to terminals 2, 5, and 7 of the communication
terminal block. Refer to the following figure.
2. Torque the wires to 2.5 in-lbs. (0.28 Nm).
3. Note down the wire color used for each of the terminals.
4. Connect the shield of the cable to the flat connection for grounding in the Sunny Boy. Refer to
the following figure.
5. Install a jumper in position A, the bottom set of pins on the communication jumper block, to set
it for termination.
Do not connect the cable shield to the PC’s DB-9 connector. The shield must remain floating
at the PC.
The termination of the other end of the RS485 cable depends on the type of device you
are connecting.
For detailed information see the Technical Information section under Service Downloads of
our web site at www.SMA-America.com.
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