Electron do Brasil EP4 IoT Modbus register map

Thermal protection relay (ANSI 23, 26, 38, 45, 49, 74, 77, 94) with four temperature sensors, alarm, shutdown, fault and ventilation relays, analog output and Modbus RTU

Official
86 registers
Modbus RTU
Revision 1 · 2026-11-10
Identity: serial number

Official: Written from the manufacturer's documentation, but not tested on a device yet. Check the map against the manufacturer's documentation before you write to a live device. Tested it? Report a test.

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Communication

Protocol: Modbus RTU
Unit ID: 1
Serial: 9600 8N1 · 9600 baud, 8 data bits, none parity, 1 stop bit
Byte / word order: ABCD · bytes big-endian, words high first
Addresses: 1-based · wire address = address − 1

Connection values are defaults: the device may be configured differently.

Map

Registers: 86 holding registers
Groups: 6
Translation tables: 6
Revision: 1 · 2026-11-10
Added: 2026-11-10 (2026-11-10)
File: maps/electron/ep4-iot.mbmap.json · 20 KB · history
SHA-256: db133223210e2e4b97e3bfdc92fe77af87b467abe03ad1eb1495d56bfab7a4b4
Manufacturer: electron.com.br

Device identity

What a tool can read to check that this map fits the connected device (SPEC.md section 4.7). Registers with a role are read like any other register.

Registers
Role	Register	Address	Type	Values
Serial number	Serial number	holding 97	uint32 ABCD

Sources and notes

Mapa de Registradores MODBUS RTU, Relé de Proteção Térmica EP4 IoT
linked in issue #129; the document linked for the EP3 in issue #128 has the same text

Source: Electron do Brasil, Mapa de Registradores MODBUS RTU, Relé de Proteção Térmica EP4 IoT

All registers are holding registers. The document numbers them 1 to 99 and calls the type Holding Register (40.000), so the addresses are 1-based (address on the wire = number minus 1). The document does not say so explicitly: if a read fails, try address_base 0.
The document allows 2400 to 57600 bps with automatic baud rate detection, 8 data bits and 1 stop bit. It gives no parity, default baud rate or slave address: 9600 N and 1 are placeholders; the slave address is in register 50.
Temperatures are shown in the document with one decimal and a scale of -1000:10, which it does not explain. They are given as raw values: check against the display before applying a scale.
Registers 26, 42, 43, 45, 46, 47, 48, 49 and 61 are bit fields, one entry per bit. The command bits are write-only. Registers 80 to 83 (map latitude, two registers each, both labelled latitude) and the maximum current-output temperature of sensor 4 are not in the document or not clear, so they are left out.
The EP3 IoT document linked in issue #128 has exactly the same content and title (EP4 IoT), so this map may not match an EP3 IoT.
Written from the manufacturer's document; not tested on a device.

Area	Address	Type	Access	Unit	Scale	Description
HR	1	uint16	RW			Range 0 to 200.0; the document's scale column (-1000:10) is not explained, so the value is raw (check against the display)
HR	2	uint16	RW			Range 0 to 200.0; the document's scale column (-1000:10) is not explained, so the value is raw (check against the display)
HR	3	uint16	RW			Range 0 to 200.0; the document's scale column (-1000:10) is not explained, so the value is raw (check against the display)
HR	4	uint16	RW			Range 0 to 200.0; the document's scale column (-1000:10) is not explained, so the value is raw (check against the display)
HR	9	uint16	RW		×0.1	Range 0 to 10.0
HR	10	uint16	RW			Range 0 to 200.0; the document's scale column (-1000:10) is not explained, so the value is raw (check against the display)
HR	11	uint16	RW			Range 0 to 200.0; the document's scale column (-1000:10) is not explained, so the value is raw (check against the display)
HR	12	uint16	RW			Range 0 to 200.0; the document's scale column (-1000:10) is not explained, so the value is raw (check against the display)
HR	13	uint16	RW			Range 0 to 200.0; the document's scale column (-1000:10) is not explained, so the value is raw (check against the display)
HR	18	uint16	RW	min
HR	19	uint16	RW			Range 0 to 200.0; the document's scale column (-1000:10) is not explained, so the value is raw (check against the display)
HR	20	uint16	RW			Range 0 to 200.0; the document's scale column (-1000:10) is not explained, so the value is raw (check against the display)
HR	21	uint16	RW			Range 0 to 200.0; the document's scale column (-1000:10) is not explained, so the value is raw (check against the display)
HR	22	uint16	RW			Range 0 to 200.0; the document's scale column (-1000:10) is not explained, so the value is raw (check against the display)
HR	24	uint16	RW
HR	25	uint16	RW
HR	26	bool bit 0	W			Write 1
HR	26	bool bit 1	W			Write 1
HR	27	uint16	RW		×0.1	Range 0 to 30.0
HR	28	uint16	RW
HR	29	uint16	R			Range 0 to 200.0; the document's scale column (-1000:10) is not explained, so the value is raw (check against the display)
HR	30	uint16	R			Range 0 to 200.0; the document's scale column (-1000:10) is not explained, so the value is raw (check against the display)
HR	31	uint16	R			Range 0 to 200.0; the document's scale column (-1000:10) is not explained, so the value is raw (check against the display)
HR	32	uint16	R			Range 0 to 200.0; the document's scale column (-1000:10) is not explained, so the value is raw (check against the display)
HR	33	int16	RW			Range -10.0 to 10.0; the document's scale column (-1000:10) is not explained, so the value is raw (check against the display)
HR	34	int16	RW			Range -10.0 to 10.0; the document's scale column (-1000:10) is not explained, so the value is raw (check against the display)
HR	35	int16	RW			Range -10.0 to 10.0; the document's scale column (-1000:10) is not explained, so the value is raw (check against the display)
HR	36	int16	RW			Range -10.0 to 10.0; the document's scale column (-1000:10) is not explained, so the value is raw (check against the display)
HR	37	uint16	R			Range 0 to 200.0; the document's scale column (-1000:10) is not explained, so the value is raw (check against the display)
HR	38	uint16	R			Range 0 to 200.0; the document's scale column (-1000:10) is not explained, so the value is raw (check against the display)
HR	39	uint16	R			Range 0 to 200.0; the document's scale column (-1000:10) is not explained, so the value is raw (check against the display)
HR	40	uint16	R			Range 0 to 200.0; the document's scale column (-1000:10) is not explained, so the value is raw (check against the display)
HR	42	bool bit 0	RW
HR	42	bool bit 1	RW
HR	42	bool bit 2	RW
HR	42	bool bit 3	RW
HR	43	bool bit 0	RW
HR	43	bool bit 1	RW
HR	43	bool bit 2	RW
HR	43	bool bit 3	RW			The document lists value 1 as Normal for this relay: taken to be a typing error
HR	45	bool bit 0	R
HR	45	bool bit 1	R
HR	45	bool bit 2	R
HR	45	bool bit 3	R
HR	46	bool bit 0	R
HR	46	bool bit 1	R
HR	46	bool bit 2	R
HR	46	bool bit 3	R			Sensor 4 is the ambient sensor
HR	47	bool bit 0	R
HR	47	bool bit 1	R
HR	47	bool bit 2	R
HR	47	bool bit 3	R			Sensor 4 is the ambient sensor
HR	48	bool bit 0	R
HR	48	bool bit 1	R
HR	48	bool bit 2	R
HR	48	bool bit 3	R
HR	48	bool bit 4	R
HR	48	bool bit 6	R
HR	48	bool bit 7	R
HR	49	bool bit 0	R
HR	49	bool bit 1	R
HR	49	bool bit 2	R
HR	49	bool bit 3	R
HR	50	uint16	R			Range 1 to 254
HR	51	uint16	RW
HR	60	uint16	RW
HR	61	bool bit 0	RW
HR	61	bool bit 1	RW
HR	61	bool bit 2	RW
HR	61	bool bit 3	RW
HR	62	uint16	RW	ms	×500	The value is the number of 500 ms periods; range 5 to 50
HR	63	int16	RW			Range -1.00 to 1.00; the document's scale column (-1000:100) is not explained, so the value is raw (check against the display)
HR	70	uint16	RW			Range 0 to 2000; the document's scale column (-1000:10) is not explained, so the value is raw (check against the display)
HR	71	uint16	RW			Range 0 to 2000; the document's scale column (-1000:10) is not explained, so the value is raw (check against the display)
HR	72	uint16	RW			Range 0 to 2000; the document's scale column (-1000:10) is not explained, so the value is raw (check against the display)
HR	73	uint16	RW			Range 0 to 2000; the document's scale column (-1000:10) is not explained, so the value is raw (check against the display)
HR	75	uint16	RW			Range 0 to 2000; the document's scale column (-1000:10) is not explained, so the value is raw (check against the display)
HR	76	uint16	RW			Range 0 to 2000; the document's scale column (-1000:10) is not explained, so the value is raw (check against the display)
HR	77	uint16	RW			Range 0 to 2000; the document's scale column (-1000:10) is not explained, so the value is raw (check against the display)
HR	92	int16	R			Range -50.0 to 250.0; the document's scale column (-1000:10) is not explained, so the value is raw (check against the display)
HR	93	int16	R			Range -50.0 to 250.0; the document's scale column (-1000:10) is not explained, so the value is raw (check against the display)
HR	94	uint16	R			Range 1 to 31
HR	95	uint16	R			Range 1 to 12
HR	96	uint16	R			Range 2020 to 2099
HR	97	uint32 ABCD	R			Registers 97 (MSB) and 98 (LSB)
HR	99	uint16	R			Range 0 to 999

Help improve this map

I tested it on a deviceReport whether it worked, even if you did not write the map.
Suggest a correctionEdit the file on GitHub; it opens a pull request.
Report a problemA wrong address, type, scale or byte order.
Read the formatWhat each key of the file means (SPEC.md).