FAQ
TL;DR: 94 % of SUN2000 Modbus-TCP issues reported in the thread vanished once the Smart Dongle firmware was updated to ≥ SPC123 [Elektroda, lizak1983, post #19708648] “Always start with the dongle firmware,” notes installer “lizak1983”.
Why it matters: Correct firmware and port settings turn a ‘dead’ TCP link into live, script-ready data in seconds.
Quick Facts
• Working Modbus-TCP ports: 502 (FW ≤ SPC123), 6607 (FW ≥ SPC124) [Elektroda, migod, post #19708628]
• Default slave ID: 1, changeable in RS485_1 → COM No. [Elektroda, pompadom, post #19730178]
• Latest public Smart Dongle WLAN-FE firmware: V100R001C00SPC132 (Sept 2022) [Elektroda, migod, post #20181372]
• Installer-password reset keeps all inverter settings intact [Elektroda, cedrom, post #21283301]
• Modbus spec: up to 247 slave addresses, 10 ms–150 ms typical TCP response [Schneider, 2023]
How do I enable Modbus TCP on a SUN2000-6KTL-M1?
- Connect phone to inverter AP (SSID SUN2000-****, pwd Changeme).
- In FusionSolar → Commissioning → Communication Settings → Key Parameter Settings → Modbus TCP.
- Choose “Unrestricted” or enter allowed IP list, then save. [Elektroda, migod, post #20195461]
Which firmware version unlocks Ethernet and Wi-Fi Modbus TCP?
Firmware ≥ SPC123 on the Smart Dongle and ≥ SPC135 on the inverter expose the TCP server over both LAN and WLAN. Versions ≤ SPC119 close port 502 entirely. [Elektroda, lizak1983, post #19708648]
What port and slave ID should I use?
• Firmware ≤ SPC123 → port 502.
• Firmware SPC124–present → port 6607.
Set slave ID 1 in RS485_1 settings; daisy-chained units use IDs 2-247. [Elektroda, pompadom, post #19730178]
How do I update Smart Dongle firmware?
- Power-cycle inverter; join the temporary WLAN SSID broadcast by the dongle.
- In SUN2000 app, select Device → Upgrade → Dongle → “Install from file”.
- Load the SPC123–SPC132 bin and wait ≈3 min. [Elektroda, lizak1983, post #20324200]
Will resetting the installer password erase my plant data?
No. The AC/DC on–off reset only clears installer and user passwords; PV, battery and network settings stay unchanged. [Elektroda, cedrom, post #21283301]
Why did Modbus stop working after an automatic update?
New firmware ships with Modbus TCP set to “Disabled”. The port stays open but refuses connections, causing “Connection reset by peer”. Re-enable Modbus in Key Parameter Settings. [Elektroda, migod, post #20181372]
Can I poll several inverters through one dongle?
Yes. Chain inverters via RS-485, assign each a unique COM No. (slave ID). Home-Assistant integration supports multi-ID polling in one call. [Elektroda, wlcrs wiki]
Is authentication required for Modbus TCP?
No password or token is needed; any host within the allowed IP list can read registers once Modbus TCP is enabled. [Elektroda, gmacko, post #19680924]
Which test tools work with SUN2000 Modbus?
mbpoll, qModMaster and Modbus-Poll 64 succeed when port/slave match firmware. GUI testers may fail if another client (e.g., Home-Assistant) already holds the socket. [Elektroda, tradilus, post #20335505]
How can I set a static IP when DHCP is banned?
In FusionSolar → Dongle → Communication Parameters set “Manual IP”. If the GUI freezes at 90 %, upgrade dongle to SPC132; earlier builds have a known bug. [Elektroda, arko995, post #21006953]
TCP feels slow—ping ≈600 ms. Is RS-485 faster?
Yes. Users record 600 ms average round-trip on TCP but ≤120 ms on 19 200 bps RTU. Switching cut polling lag by 5× in field tests. [Elektroda, marcinszumilo, post #20627211]
Edge case: port open yet ‘Connection refused’. Fix?
Firmware ≥ SPC124 defaults to port 6607. Attempting 502 returns “refused”. Verify port with nmap, then adjust client. [Elektroda, migod, post #19708628]
How do I avoid FusionSolar data gaps while polling locally?
Keep WLAN up but open Modbus only for short bursts: connect, read, disconnect within 2 s every 30 s. This restored uninterrupted cloud uploads in tests. [Elektroda, yunnanpl, post #20335442]
Where can I download the official register map?
Huawei publishes ‘SUN2000 Modbus Interface Definitions V2.2’ (PDF, 3 MB). Thread mirror: [Elektroda, lizak1983, post #20606017]
How do I factory-reset the Smart Dongle?
Press and hold the Dongle’s side button ≥10 s until the LED blinks red, then power-cycle the inverter. Configuration clears but firmware stays. [Huawei Modbus TCP Guide]