SunSpec Model 64410 — DC Simulator Control Interface
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.
- Protocol
- Modbus TCP
- Connection
- Ethernet, Modbus TCP
- Registers
- 36, read and write
- Brand
- SunSpec
- Last updated
Registers (36)
36 read, 27 write
| Name | Unit | Access | Address (Hidden until you enter your email) | Function (hidden) | Type (hidden) |
|---|---|---|---|---|---|
| id | Read | ||||
| l | Read | ||||
| vmaxlim | V | Read and write | |||
| pmaxlim | W | Read and write | |||
| imaxlim | A | Read and write | |||
| mode | Read and write | ||||
| ena | Read and write | ||||
| reset | Read and write | ||||
| vset | V | Read and write | |||
| pset | W | Read and write | |||
| iset | A | Read and write | |||
| en50530 | Read and write | ||||
| vmpp | V | Read and write | |||
| pmpp | W | Read and write | |||
| gset | W/m^2 | Read and write | |||
| vslewrate | V/s | Read and write | |||
| pslewrate | W/s | Read and write | |||
| islewrate | A/s | Read and write | |||
| enaprof | Read and write | ||||
| adptprofreq | Read and write | ||||
| adptprofrslt | Read | ||||
| v | V | Read | |||
| p | W | Read | |||
| i | A | Read | |||
| errors | Read | ||||
| npt | Read | ||||
| nprof | Read | ||||
| w_sf | Read and write | ||||
| v_sf | Read and write | ||||
| a_sf | Read and write | ||||
| g_sf | Read and write | ||||
| tms_sf | Read and write | ||||
| vslew_sf | Read and write | ||||
| pslew_sf | Read and write | ||||
| islew_sf | Read and write | ||||
| pct_sf | Read and write |
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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
- Monitor actual v, p, and i feedback during MPPT efficiency sweeps to verify inverter tracking accuracy.
- Alert on vmaxlim or imaxlim violations during automated test sequences to catch simulator overloads early.
- Track vmpp and pmpp setpoint changes across a test run to reconstruct the I-V curve profile applied to the inverter.
- Verify that the ena register is de-asserted correctly after each test cycle to confirm safe output shutdown.
- Compare pslewrate and vslewrate setpoints against actual output ramp behaviour to validate dynamic response tests.
Installation
Enable Modbus TCP on the DC simulator or test controller: navigate to the communication or Modbus section of its configuration interface and confirm port 502 is active.
Connect the DC simulator to the same LAN segment as the ModbusCloud Gateway using a standard Ethernet cable, and note the simulator's IP address.
In the ModbusCloud portal, add the Gateway, import the SunSpec Model 64410 template, and assign the correct unit ID matching the simulator's configured Modbus slave address.
Spot-check the id register (address 0): it must return 64410. Then read the v and p feedback registers to confirm live data is flowing and scale factors are applied correctly.
Things to watch for
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.
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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