Why does the id register return an unexpected value?

The register addresses in this template are relative offsets within the Model 125 block, not absolute Modbus addresses. You must add the model's base address on the device to each offset. If id does not return 125, the base address is wrong. Scan from the SunSpec start address (typically 40001) to locate the correct block position.

Modena is set but the device shows no response. Why?

Some devices require the entire SunSpec header to be present and the common model to be read first before accepting writes to control models. Also verify that sigtype is set to a supported enum value (1 to 4). Writing an unsupported SigType value (0=unknown) may cause the device to ignore the signal silently.

The sig value reads back differently than what was written. Is scaling applied?

Yes. The actual pricing signal value is sig multiplied by 10 raised to the power of sig_sf. Read sig_sf first to determine the exponent. For example, sig=150 with sig_sf=-1 represents a value of 15.0. Always read sig_sf before interpreting or writing sig.

Is it safe to write sig and modena during live grid operation?

Use caution. Writing to modena, sigtype, or sig on a live device triggers immediate or ramped changes to inverter charge and discharge behavior. An incorrect signal value or a misconfigured wintms/rvttms could cause the system to violate grid operator requirements or trip protection limits. Always test writes during commissioning with the system islanded or at low load, and confirm rvttms is set so the device reverts if communication is lost.

Free Modbus template: SunSpec Model 125 — Pricing

Name: SunSpec Model 125 — Pricing
Brand: SunSpec
SKU: 6d46d635-f10b-4c8c-97ac-597ef9ffd63a

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Free Modbus template: SunSpec Model 125 — Pricing | ModbusCloud

Registers (9)

9 read / 6 write

Name	Address	Function	Type	Unit	Access
id SunSpec model identifier, fixed value 125 for Pricing Signal.	0	FC03	uint16		R
l Model block length in registers, used for SunSpec model discovery.	1	FC03	uint16		R
modena Pricing signal enable flag; set bit 0 to activate the pricing control.	2	FC03	bool		R/W
sigtype Pricing signal type: 0=unknown, 1=absolute, 2=relative, 3=multiplier, 4=level.	3	FC03	uint16		R/W
sig Pricing signal value, scaled by sig_sf; qualitative level: 0=low, 1=medium, 2=high.	4	FC03	int16		R/W
wintms Random time window in seconds before the pricing change takes effect.	5	FC03	uint16	Secs	R/W
rvttms Reversion timeout in seconds before returning to default operation.	6	FC03	uint16	Secs	R/W
rmptms Ramp time in seconds to transition to the new charge or discharge level.	7	FC03	uint16	Secs	R/W
sig_sf Scale factor for sig, expressed as a power-of-ten exponent.	8	FC03	int16		R