SunSaver MODBUS Specifications

General Information
The SunSaver MPPT supports the industry standard MODBUS® application protocol via its Meter RJ-11
interface. A Meterbus to Serial Converter (MSC) is required to adapt the Meter interface to an isolated RS-232
interface**. This document assumes the user is familiar with the MODBUS® protocol and its terminology.
Please refer to the documents listed in the References section for more information.
** The MSC adapter is a Morningstar accessory. Contact your dealer for more information.
MODBUS® is a registered trademark of Modbus-IDA (www.modbus-ida.org)
Parameters
The SunSaver MPPT supports RTU mode only.
16bit MODBUS® addresses (per the modbus.org spec)
The serial communication parameters are
 BPS: 9600 baud
 Parity: None
 Data bits: 8
 Stop bits: 2
 Flow control: None
All addresses listed are for the request PDU.
The SunSaver MPPT default server address: 0x01.
Supported MODBUS® Functions
Read Holding Registers (0x03) and Read Input Registers (0x04)
RAM
PDU
Addr
Logical
Addr
Variable name Variable description Units Scaling or
Range
0x0008 9 Adc_vb_f Battery voltage, filtered (τ ≈ 1s) V n·100·2
-15
0x0009 10 Adc_va_f Array voltage, filtered (τ ≈ 1s) V n·100·2
-15
0x000A 11 Adc_vl_f Load voltage, filtered (τ ≈ 1s) V n·100·2
-15
0x000B 12 Adc_ic_f Charging current, filtered (τ ≈ 1s) A n·79.16·2
-
15
0x000C 13 Adc_il_f Load current, filtered (τ ≈ 1s) A n·79.16·2
-
15
0x000D 14 T_hs Heatsink temperature ºC -128 to
+127
0x000E 15 T_batt Battery temperature (Either ambient or RTS if
connected)
ºC -127 to
+127
0x000F 16 T_amb Ambient temperature ºC -127 to
+127
0x0010 17 T_rts Remote battery temperature sensor (0x80 if not ºC -127 to