SR30-M2-D1 (digital Class A pyranometer) Modbus register map

Notes

RS-485 device: reach it through a Modbus RTU-to-TCP gateway using the factory serial settings above. Source: Hukseflux "SR30-M2-D1 user manual" v2508, section 6.2 (tables 6.2.1 and 6.2.2), section 10.11 (table 10.11.1 supported function codes, table 10.11.2 Modbus registers 0-199, table 10.11.3 coils) and table 3.1.1 (digital communication specifications), published at https://www.hukx.com/uploads/SR30-M2-D1-user-manual.pdf . Factory serial settings from table 3.1.1: 19200 bps, eight data bits, even parity, one stop bit, device address 1 (register 0). The register numbers of the manual are the wire addresses (no offset), and the sensor does not distinguish input from holding registers nor coils from discrete inputs - both function codes 0x03 and 0x04 read the same cells - so the measurements are listed as input registers and the two writable setup cells plus the four control bits are listed as holding registers and coils. Each 32-bit value must be read in a single request; the sensor answers at most five 16-bit registers per request, so longer blocks (for example the two 4-register ASCII model strings) must be split. Bit values, history blocks (48-97), factory-use ranges (12-31, 41-60 reserved parts, 83-97, 100-137, 139-193, 195, 197) and the polynomial temperature coefficients are documented in table 10.11.2 but are not repeated here. Reading registers 0x0002/0x0003 once per second and averaging over 60 s is the vendor's recommended measuring cycle.