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Sungrow Sungrow SG CX Modbus RTU template

Sungrow SG CX

Commercial three-phase PV string inverter with string current monitoring and power limitation.

The Sungrow SG CX is a three-phase string inverter that converts solar power into grid power on commercial roofs and carports, from 25 to 125 kW. This Modbus RTU template reads power, yield, grid values, MPPT and string currents and fault codes, and lets you set the power limit, power factor and reactive power mode from ModbusCloud.

Protocol
Modbus RTU
Connection
RS485, 9600 baud
Registers
158, read and write
Brand
Sungrow
Key readings
AC active power · Daily energy yield · Total energy yield · Grid voltage and current · MPPT voltage and current · String currents · Work state · Fault code
Available commands
Start and stop · Active power limit · Power factor · Reactive power mode
Compatible models
SG25CX-SA · SG30CX · SG33CX · SG36CX-US · SG40CX · SG50CX · SG60CX-US · SG49.5CX-JP · SG75CX · SG100CX · SG100CX-JP · SG110CX · SG25CX-P2 · SG30CX-P2 · SG33CX-P2 · SG36CX-P2 · SG40CX-P2 · SG50CX-P2 · SG75CX-P2 · SG110CX-P2 · SG125CX-P2
Last updated

Registers (158)

158 read, 45 write

NameUnitAccessAddress (Hidden until you enter your email)Function (hidden)Type (hidden)
Total Active PowerWRead
Daily Power YieldkWhRead
Total Power YieldkWhRead
Total Power Yield kWhkWhRead
Monthly Power YieldkWhRead
Total DC PowerWRead
Total Reactive PowervarRead
Total Apparent PowerVARead
Power FactorRead
Grid FrequencyHzRead
Grid Frequency 0.1 HzHzRead
Phase A VoltageVRead
Phase B VoltageVRead
Phase C VoltageVRead
Phase A CurrentARead
Phase B CurrentARead
Phase C CurrentARead
Internal Temperature°CRead
Array Insulation ResistancekΩRead
Negative Voltage To GroundVRead
Bus VoltageVRead
MPPT 1 VoltageVRead
MPPT 1 CurrentARead
MPPT 2 VoltageVRead
MPPT 2 CurrentARead
MPPT 3 VoltageVRead
MPPT 3 CurrentARead
MPPT 4 VoltageVRead
MPPT 4 CurrentARead
MPPT 5 VoltageVRead
MPPT 5 CurrentARead
MPPT 6 VoltageVRead
MPPT 6 CurrentARead
MPPT 7 VoltageVRead
MPPT 7 CurrentARead
MPPT 8 VoltageVRead
MPPT 8 CurrentARead
MPPT 9 VoltageVRead
MPPT 9 CurrentARead
MPPT 10 VoltageVRead
MPPT 10 CurrentARead
MPPT 11 VoltageVRead
MPPT 11 CurrentARead
MPPT 12 VoltageVRead
MPPT 12 CurrentARead
MPPT 13 VoltageVRead
MPPT 13 CurrentARead
MPPT 14 VoltageVRead
MPPT 14 CurrentARead
MPPT 15 VoltageVRead
MPPT 15 CurrentARead
MPPT 16 VoltageVRead
MPPT 16 CurrentARead
String 1 CurrentARead
String 2 CurrentARead
String 3 CurrentARead
String 4 CurrentARead
String 5 CurrentARead
String 6 CurrentARead
String 7 CurrentARead
String 8 CurrentARead
String 9 CurrentARead
String 10 CurrentARead
String 11 CurrentARead
String 12 CurrentARead
String 13 CurrentARead
String 14 CurrentARead
String 15 CurrentARead
String 16 CurrentARead
String 17 CurrentARead
String 18 CurrentARead
String 19 CurrentARead
String 20 CurrentARead
String 21 CurrentARead
String 22 CurrentARead
String 23 CurrentARead
String 24 CurrentARead
String 25 CurrentARead
String 26 CurrentARead
String 27 CurrentARead
String 28 CurrentARead
String 29 CurrentARead
String 30 CurrentARead
String 31 CurrentARead
String 32 CurrentARead
Work StateRead
Work State BitsRead
Fault Alarm CodeRead
Fault Time YearRead
Fault Time MonthRead
Fault Time DayRead
Fault Time HourRead
Fault Time MinuteRead
Fault Time SecondRead
Work Status 1Read
Work Status 2Read
PID Work StateRead
PID Alarm CodeRead
Active Power Regulation SetpointWRead
Reactive Power Regulation SetpointvarRead
Heart BeatRead
Start StopRead and write
Power Limitation SwitchRead and write
Power Limitation Setting%Read and write
Power Limitation AdjustmentkWRead and write
Active Power OverloadRead and write
Reactive Power Adjustment ModeRead and write
Power Factor SettingRead and write
Reactive Power Percentage Setting%Read and write
Reactive Power AdjustmentkvarRead and write
Night SVG SwitchRead and write
PID RecoveryRead and write
Anti PIDRead and write
Local Remote ControlRead and write
Installed PV PowerkWRead and write
System Clock YearRead and write
System Clock MonthRead and write
System Clock DayRead and write
System Clock HourRead and write
System Clock MinuteRead and write
System Clock SecondRead and write
QP CurveRead and write
QP P1%Read and write
QP P2%Read and write
QP P3%Read and write
QP K1Read and write
QP K2Read and write
QP K3Read and write
QP Enter Voltage Ratio%Read and write
QP Exit Voltage Ratio%Read and write
QP Exit Power Ratio%Read and write
QP Enable ModeRead and write
QU CurveRead and write
QU Hysteresis Ratio%Read and write
QU V1%Read and write
QU Q1%Read and write
QU V2%Read and write
QU Q2%Read and write
QU V3%Read and write
QU Q3%Read and write
QU V4%Read and write
QU Q4%Read and write
QU Enter Power%Read and write
QU Exit Power%Read and write
QU Enable ModeRead and write
QU Limit PF ValueRead and write
Device Type CodeRead
Nominal Active PowerkWRead
Nominal Reactive PowerkvarRead
Output TypeRead
Total Running TimehRead
Daily Running TimeminRead
Present CountryRead
Serial NumberRead
Protocol NumberRead
Protocol VersionRead
ARM Software VersionRead
DSP Software VersionRead

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If a device is not in the library yet, we build the template for free as soon as we have the register data.

Number of installations (optional)

Use cases

  • Show AC power and daily yield of every inverter on one dashboard to compare roofs or inverters.
  • Get an email alert when the fault code is not 0 or the work state switches to fault.
  • Compare string currents over months to find a shaded, soiled or disconnected string.
  • Watch insulation resistance and get an alert when it drops toward the trip level.
  • Lower the active power limit from ModbusCloud when the grid connection is constrained.

Installation

  1. Connect RS485 A and B of the inverter to the RS485 port of the ModbusCloud Gateway, with a 120 ohm terminator at both ends of the bus.

  2. Give each inverter its own Modbus address in the iSolarCloud app and use 9600 baud, 8 data bits, no parity, 1 stop bit.

  3. In ModbusCloud, add a Modbus device with that address and import this template.

  4. Check that Device Type Code shows your model and that Total Active Power follows the inverter display.

Things to watch for

The inverter does not answer on RS485. What should I check?

Check address, baud rate and parity against the settings in the iSolarCloud app, then swap A and B. Every inverter on the bus needs a unique address, and the bus needs a terminator at both ends. Some installations already have a data logger as master on the same RS485 port; two masters on one bus do not work.

Why do some MPPT or string registers show 6553.5 or 655.35?

Those inputs do not exist on your model, or the hardware does not measure that string. The inverter returns 65535 for them. Remove those registers from the device in ModbusCloud or ignore them on the dashboard.

Total power and energy look far too large. Why?

The 32-bit values send the low word first. The template already sets that word order. If you entered registers by hand, set the same word order, otherwise a few kW reads as millions.

What should I know before writing the power limit or start and stop?

The power limit only works after Power Limitation Switch is set to enable (170). Writing 206 to Start Stop stops the inverter and it stays off until you write 207. Agree changes with the owner and the grid operator, because a wrong limit or reactive power setting can cost yield or break grid rules.

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