Seplos 48V BMS (RS485)

Register map(s) for this device, with a note of how far each has been checked. Addresses are 0-based, as on the wire. Scale and byte order are confirmed only at the hardware-verified rung.

coherence-checked

Round-trips through a real Modbus stack with no overlapping addresses and a word-order-sensitive codec — the map is internally coherent and wire-decodable. Does NOT prove byte-order or scaling match a real device: the emulator is seeded from the map's own types, so a uniformly wrong byte-order still round-trips. Only hardware-verified confirms byte-order/scale on the wire.

point	address (0-based)	type	scale
cell_1_voltage	1	U16	0.001
cell_2_voltage	2	U16	0.001
cell_3_voltage	3	U16	0.001
cell_4_voltage	4	U16	0.001
cell_5_voltage	5	U16	0.001
cell_6_voltage	6	U16	0.001
cell_7_voltage	7	U16	0.001
cell_8_voltage	8	U16	0.001
cell_9_voltage	9	U16	0.001
cell_10_voltage	10	U16	0.001
cell_11_voltage	11	U16	0.001
cell_12_voltage	12	U16	0.001
cell_13_voltage	13	U16	0.001
cell_14_voltage	14	U16	0.001
cell_15_voltage	15	U16	0.001
cell_16_voltage	16	U16	0.001
cell_1_temperature	18	U16	0.1
cell_2_temperature	19	U16	0.1
cell_3_temperature	20	U16	0.1
cell_4_temperature	21	U16	0.1
ambient_temperature	22	U16	0.1
components_temperature	23	U16	0.1
pack_current	24	I16	0.01
pack_voltage	25	U16	0.01
remaining_capacity	26	U16	0.01
battery_capacity	27	U16	0.01
soc	28	U16	0.1
rated_capacity	29	U16	0.01
cycle_life	30	U16	1
soh	31	U16	0.1
port_voltage	32	U16	0.01

link settings as documented (unverified): ASCII; Uses YD/T1363.3 standard-based ASCII protocol (referred to as MODBUS-ASCII in document) with SOI (~), VER, ADR, CID1, CID2, LENGTH, INFO, CHKSUM, EOI.

bench facts as documented (unverified)

terminals	RS232 and RS485
termination	120Ω
wiring notes	Asynchronous serial communication interface with 1 start bit, 8 data bits, 1 stop bit, and no parity.
broadcast	supported
protocol notes	SU sends control messages to SM through broadcast addresses. SM sends feedback to SU.

field reports — community-sourced, unverified (checked 2026-06-11)

Baud rate confusion: Users often struggle to connect because some firmware versions default to 19200 baud instead of 9600 baud. [source]
RS485 lockup issue: The BMS RS485 interface can stop responding entirely after some time due to electromagnetic interference (EMI) or bus disturbance, requiring a physical reboot of the BMS to recover. [source]
CAN/RS485 conflict: If the master battery is communicating with an inverter via CAN, the master's RS485 port becomes unreadable because it is occupied managing intra-pack communication with slave batteries. [source]
Physical pinout surprise: On some hardware revisions, RS485 is routed through the CAN socket on RJ45 pins 1 and 2 (A and B), with ground disconnected. [source]
confirmed: Uses YD/T1363.3 standard-based ASCII protocol with SOI (~), VER, ADR, CID1, CID2, LENGTH, INFO, CHKSUM, EOI — confirmed by Seplos BMS Communication Protocol V2.0 PDF and GitHub implementations
confirmed: Asynchronous serial communication interface with 1 start bit, 8 data bits, 1 stop bit, and no parity — confirmed by Seplos BMS Communication Protocol V2.0 PDF
confirmed: Broadcast supported where SU sends control messages to SM through broadcast addresses — confirmed by Seplos BMS MODBUS-ASCII Protocol Guide

The trust ladder

Each rung states what it proved and what it did not. Gray until proven; green is earned by hardware only.

generated — A prompt produced it. Unproven — anyone can regenerate this.
structure-verified — Decode path is structurally sound (addresses, widths, finite values). Does NOT prove word order or scaling.
coherence-checked — Round-trips through a real Modbus stack with no overlapping addresses and a word-order-sensitive codec — the map is internally coherent and wire-decodable. Does NOT prove byte-order or scaling match a real device: the emulator is seeded from the map's own types, so a uniformly wrong byte-order still round-trips. Only hardware-verified confirms byte-order/scale on the wire.
hardware-verified (software-key) x1 — Matched a real device with operator-attested readings as ground truth — the only rung that confirms word order + scaling on the wire.

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