SunSpec Model 13 — IPv6
SunSpec Model 13 is the standardised IPv6 network interface configuration model defined by the SunSpec Alliance for DER devices. Any SunSpec-compliant inverter, energy storage system, or energy meter that exposes this model over Modbus TCP allows a management system to read and write its IPv6 address, subnet prefix, gateway, DNS servers, NTP servers, domain name, and hostname. The template covers configuration status, change-pending state, and capability flags alongside all address-string registers. Using this template in your ModbusCloud portal gives installers a single, vendor-neutral view of network configuration across mixed-device sites.
- Protocol
- Modbus TCP
- Connection
- Ethernet, Modbus TCP
- Registers
- 17, read and write
- Brand
- SunSpec
- Last updated
Registers (17)
17 read, 12 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| id | Read | ||||
| l | Read | ||||
| nam | Read and write | ||||
| cfgst | Read | ||||
| chgst | Read | ||||
| cap | Read | ||||
| cfg | Read and write | ||||
| ctl | Read and write | ||||
| addr | Read and write | ||||
| cidr | Read and write | ||||
| gw | Read and write | ||||
| dns1 | Read and write | ||||
| dns2 | Read and write | ||||
| ntp1 | Read and write | ||||
| ntp2 | Read and write | ||||
| domnam | Read and write | ||||
| hostnam | Read and write |
Loading registers…
Send your device list
If a device is not in the library yet, we build the template for free as soon as we have the register data.
Use cases
- Verify the active IPv6 address and gateway on a DER device after a network reconfiguration.
- Monitor the configuration status register to confirm a static IPv6 address is accepted and active.
- Alert on a PENDING change-status flag that indicates a control write has not yet been applied.
- Track the capability bitfield to confirm NTP client support before relying on device timestamps.
- Audit DNS and NTP server assignments across multiple SunSpec devices on a multi-site installation.
Installation
Confirm that the target device supports SunSpec Model 13 by checking its documentation or scanning the SunSpec model list starting at Modbus holding register 40001.
Connect the ModbusCloud Gateway to the same LAN segment as the SunSpec device and ensure TCP port 502 is reachable from the Gateway to the device IP address.
In the ModbusCloud portal, add the Gateway, import the SunSpec Model 13 template, and set the unit ID and base address offset to match the device's Modbus map start (commonly 40000 offset).
Read the id register and verify it returns 13, then read cfgst to confirm the interface reports VALID_SETTING or VALID_HW before polling address-string registers.
Things to watch for
Why do the address string registers return all nulls?
SunSpec strings are NULL-terminated and NULL-padded. A register block filled with 0x0000 means the field is unimplemented or unconfigured on this device. Confirm the device actually supports IPv6 and that cfgst is not 0 (NOT_CONFIGURED) before reading addr, gw, or dns registers.
The gateway shows a connection but cfgst stays at 0. What is wrong?
A cfgst value of 0 means NOT_CONFIGURED: the device has no valid IPv6 address assigned. Check whether the cfg register is set to DHCP (1) and whether the cap bitfield confirms DHCP capability. If cfg is STATIC (0), a valid addr and cidr must be written first, followed by a ctl apply command.
Writing addr or gw drops the Modbus TCP connection immediately. Is this expected?
Yes. Writing network configuration registers such as addr, gw, cfg, or ctl can cause the device to reconfigure its network interface and temporarily drop all TCP connections, including the active Modbus session. Wait several seconds and reconnect. Do not write these registers during active monitoring cycles without a reconnection strategy in your client.
Is it safe to write cfg, ctl, or addr registers at any time?
Write registers in this model directly affect the device's live network stack. An incorrect addr or cidr value can make the device unreachable on the network. Always verify the intended values before writing, test on one device before rolling out to a site, and ensure a local fallback access method exists in case connectivity is lost.
Knowledge base articles for this device
SunSpec Modbus: one register map for many inverters
SunSpec Modbus is the open register map SMA, Fronius, SolarEdge and Kostal share. The layout, int+SF vs float, the TCP port per brand and reading a mixed fleet.
Fronius Modbus: read a Symo GEN24 over Modbus TCP
Fronius Modbus explained: enable Modbus TCP on the Symo GEN24 on port 502, choose between int+SF and float, read the right SunSpec registers and scale them correctly. Practical guide for solar installers.
SMA Modbus: reading a Sunny Boy over Modbus TCP (installers)
SMA Modbus explained: enable the Modbus TCP server on port 502, choose between the SMA profile (unit ID 3) and SunSpec (unit ID 126), read the right registers, and handle the NaN values at night. Practical guide for installers.
Want to see how it works?
