Why do v, p, and i read as unexpectedly large or small numbers?

These int32 registers must be multiplied by 10 raised to the power of their respective scale factor registers (v_sf, w_sf, a_sf). Read the scale factor registers first. A v_sf value of -2, for example, means the raw v value must be divided by 100 to obtain volts.

The gateway connects but all setpoint registers return zero. What now?

The ena register (address 6) must be written with a non-zero value before the simulator activates its output. If ena is 0 the device holds all outputs at zero regardless of vset, pset, or iset. Confirm the mode register is set to the intended control mode before enabling.

Is it safe to write vset, pset, or vmaxlim during a live test?

Write registers including vset, pset, iset, vmaxlim, pmaxlim, and imaxlim directly affect the simulator's electrical output. Exceeding the connected inverter's rated input range can trigger protection faults, corrupt ongoing test results, or invalidate certification runs. Always verify limit registers before enabling output.

EN 50530 mode is enabled but MPPT efficiency results look wrong. Why?

When en50530 is set to 1, the simulator switches to an EN 50530-compliant I-V curve shape driven by vmpp and pmpp. Confirm that the g_sf scale factor is correctly applied to gset so the irradiance value passed to the curve algorithm is accurate. Incorrect g_sf causes a distorted I-V characteristic.

Free Modbus template: SunSpec Model 64410 — DC Simulator Control Interface

Name: SunSpec Model 64410 — DC Simulator Control Interface
Brand: SunSpec
SKU: d63cafda-a464-4d60-8bec-5941ddbc1b63

SunSpec Model 64410 is a DC Simulator Control Interface designed for solar inverter test laboratories and DER certification rigs. It represents a programmable DC source that emulates a PV array over Modbus TCP, allowing test systems to set voltage, power, and current output points alongside a simulated I-V curve defined by vmpp and pmpp. The template reads actual output feedback via the v, p, and i registers, and controls output limits (vmaxlim, pmaxlim, imaxlim), slew rates, EN 50530 MPPT efficiency test mode, and profile playback. All scaled values use SunSpec-standard scale factor registers. Connecting a ModbusCloud Gateway to a 64410-compatible simulator brings full remote visibility and command logging into one portal.

Registers (36)

36 read / 27 write

Name	Address	Function	Type	Unit	Access
id SunSpec model identifier, fixed value 64410 for this model.	0	FC03	uint16		R
l Length of this model block in Modbus registers.	1	FC03	uint16		R
vmaxlim Maximum output voltage limit, volts, enforced by the simulator.	2	FC03	uint16	V	R/W
pmaxlim Maximum output power limit, watts, enforced by the simulator.	3	FC03	uint16	W	R/W
imaxlim Maximum output current limit, amperes, enforced by the simulator.	4	FC03	uint16	A	R/W
mode Operating mode selector: voltage, current, or power control mode.	5	FC03	uint16		R/W
ena Enable flag; write 1 to activate simulator output, 0 to disable.	6	FC03	uint16		R/W
reset Reset command; write 1 to reset the simulator to default state.	7	FC03	uint16		R/W
vset Output voltage setpoint, volts, for voltage-control mode.	8	FC03	uint16	V	R/W
pset Output power setpoint, watts, for power-control mode.	9	FC03	uint16	W	R/W
iset Output current setpoint, amperes, for current-control mode.	10	FC03	uint16	A	R/W
en50530 EN 50530 MPPT efficiency test mode enable flag.	11	FC03	uint16		R/W
vmpp Maximum power point voltage setpoint, volts, for PV curve simulation.	12	FC03	uint16	V	R/W
pmpp Maximum power point power setpoint, watts, for PV curve simulation.	13	FC03	uint16	W	R/W
gset Simulated irradiance setpoint, watts per square metre.	14	FC03	uint16	W/m^2	R/W
vslewrate Voltage slew rate limit, volts per second, for output transitions.	15	FC03	uint16	V/s	R/W
pslewrate Power slew rate limit, watts per second, for output transitions.	16	FC03	uint16	W/s	R/W
islewrate Current slew rate limit, amperes per second, for output transitions.	17	FC03	uint16	A/s	R/W
enaprof Profile playback enable flag; write 1 to start a stored profile.	18	FC03	uint16		R/W
adptprofreq Adaptive profile request; write to trigger a profile adaptation cycle.	19	FC03	uint16		R/W
adptprofrslt Adaptive profile result code, read after an adaptation request.	20	FC03	uint16		R
v Actual output voltage feedback, signed 32-bit, apply v_sf scale factor.	21	FC03	int32	V	R
p Actual output power feedback, signed 32-bit, apply w_sf scale factor.	23	FC03	int32	W	R
i Actual output current feedback, signed 32-bit, apply a_sf scale factor.	25	FC03	int32	A	R
errors Active error string; empty when no fault is present.	27	FC03	string		R
npt Number of points in the current I-V curve profile table.	59	FC03	uint16		R
nprof Number of stored profiles available for playback.	60	FC03	uint16		R
w_sf Power scale factor, signed exponent applied to all watt values.	61	FC03	int16		R/W
v_sf Voltage scale factor, signed exponent applied to all volt values.	62	FC03	int16		R/W
a_sf Current scale factor, signed exponent applied to all ampere values.	63	FC03	int16		R/W
g_sf Irradiance scale factor, signed exponent applied to gset value.	64	FC03	int16		R/W
tms_sf Time scale factor, signed exponent applied to time-related values.	65	FC03	int16		R/W
vslew_sf Voltage slew rate scale factor, signed exponent for vslewrate.	66	FC03	int16		R/W
pslew_sf Power slew rate scale factor, signed exponent for pslewrate.	67	FC03	int16		R/W
islew_sf Current slew rate scale factor, signed exponent for islewrate.	68	FC03	int16		R/W
pct_sf Percentage scale factor, signed exponent for percentage-based values.	69	FC03	int16		R/W