SunSpec Model 19 — PPP Link
SunSpec Model 19 is a standardised PPP (Point-to-Point Protocol) link-layer configuration model published by the SunSpec Alliance for distributed energy resource devices. It is part of the SunSpec network-interface model series and is accessed over Modbus TCP. The template reads the model identifier and block length, and exposes read-write registers covering baud rate, data bits, parity, duplex mode, flow control, PPP authentication type, username, and password. Importing this template into your portal lets you inspect and adjust the serial PPP link parameters of any SunSpec-compliant device without opening a separate configuration tool.
- Protocol
- Modbus TCP
- Connection
- Ethernet, Modbus TCP
- Registers
- 11, read and write
- Brand
- SunSpec
- Last updated
Registers (11)
11 read, 6 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| id | Read | ||||
| l | Read | ||||
| nam | Read and write | ||||
| rte | bps | Read and write | |||
| bits | Read and write | ||||
| pty | Read and write | ||||
| dup | Read and write | ||||
| flw | Read and write | ||||
| auth | Read | ||||
| usrnam | Read | ||||
| pw | Read |
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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.
Use cases
- Verify baud rate and parity settings on a newly commissioned SunSpec device to confirm they match your serial network.
- Track PPP authentication type to ensure devices on a shared network are using CHAP rather than PAP where required.
- Monitor the interface name register to distinguish multiple PPP links on multi-port SunSpec gateways in the portal.
- Alert on unexpected changes to flow control or duplex settings that could silently degrade serial communication throughput.
- Compare PPP link configuration across multiple sites to detect non-standard baud rate or data-bit mismatches.
Installation
Enable Modbus TCP on the host device through its web interface or local display, under the communication or Modbus section, and note the assigned IP address and TCP port (default 502).
Connect the host device to the same LAN as the ModbusCloud Gateway, or ensure IP routing between them, and confirm the device responds to a ping from the Gateway.
In the ModbusCloud portal, add the Gateway, create a new device, import the SunSpec Model 19 PPP Link template, and enter the device IP address, port, and Modbus unit ID.
Trigger a manual poll in the portal and spot-check the id register: it must read 19, confirming the correct SunSpec model block is being addressed.
Things to watch for
The id register returns an unexpected value. What does that mean?
The id register must equal 19 for this model. A different value means the Modbus base address is pointing at a different SunSpec model block. SunSpec devices place models sequentially in holding registers starting at address 40001, 0, or 50000. Scan the device map to locate the block whose id reads 19, then adjust the template base offset accordingly.
All registers return zeros or not-implemented. Why?
Not all SunSpec-compliant devices implement Model 19. If the device does not have a PPP serial interface, the block is either absent or filled with not-implemented sentinel values (0xFFFF for uint16, 0x80000000 for uint32). Confirm via the device datasheet that a PPP link interface is present before troubleshooting further.
I changed the baud rate or parity via a write register and lost communication. What now?
Writing to the rte, bits, pty, dup, or flw registers reconfigures the live serial interface immediately on compliant devices. If the new values do not match your serial network, communication drops instantly. Always verify the target values match every node on the bus before writing, and keep a record of the previous values so you can restore them from a local console.
The gateway connects but the usrnam and pw registers read empty. Is that a fault?
No. When PPP authentication is disabled (auth = 0 or not-implemented), the username and password registers are unused and may return empty strings or not-implemented values. Only populate or write these fields if the auth register confirms an authentication mode such as PAP or CHAP is active on the link.
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.
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