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  2. Electron do Brasil
  3. MasterTemp

Electron do Brasil MasterTemp Modbus register map

Transformer temperature monitor (ANSI 49I/49) with oil and winding temperatures, thermal image, fan groups, analog outputs and Modbus RTU

  • Official
  • 150 registers
  • Modbus RTU
  • Revision 1 · 2026-11-10

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
150 holding registers
Groups
8
Translation tables
13
Revision
1 · 2026-11-10
Added
()
File
maps/electron/mastertemp.mbmap.json · 32 KB · history
SHA-256
42ce7bb07a43654e2ec11cf3a9b2edc21e065dc02427c24c62a0bd2b6066a828
Manufacturer
electron.com.br

Sources and notes

Source: Electron do Brasil, Mapa de Registradores MODBUS RTU, MasterTemp, v7.0

  • All registers are holding registers. The document numbers them from 1 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, 1 stop bit and no, even or odd parity. It gives no default baud rate or slave address: 9600 N and 1 are placeholders. Register 92 holds the parity setting.
  • Temperatures have the scale -1000:10 in the document. It is read here as: value = raw / 10 - 100, which fits the stated range of -50.0 to 250.0 with raw values from 500 to 3500. This reading is not confirmed by the document: check one value against the display.
  • Other scales in the document are written as 1:N and are read as raw / N. Registers whose scale column is unclear are given as raw values.
  • The document names the alarm temperatures of registers 2 to 4 'sensor 1 to 3' and the shutdown and fan temperatures 'winding 1 to 3'; the names here follow the document.
  • Registers 15, 20, 46, 47, 49 are not in the document. Registers 76, 101, 108 to 118 and 140 to 149 are left out because their descriptions in the document are repeated, garbled or inconsistent.
  • Registers 5, 10, 45, 48, 50, 52, 75 and 79 are bit fields, one entry per bit. The command bits of register 45 are write-only.
  • Written from the manufacturer's document; not tested on a device.
AreaAddressNameTypeAccessUnitScaleDescription
HR 1 uint16 RW °C ×0.1 −100
HR 2 uint16 RW °C ×0.1 −100
HR 3 uint16 RW °C ×0.1 −100
HR 4 uint16 RW °C ×0.1 −100
HR 5 bool bit 0 RW
HR 6 uint16 RW °C ×0.1 −100
HR 7 uint16 RW °C ×0.1 −100
HR 8 uint16 RW °C ×0.1 −100
HR 9 uint16 RW °C ×0.1 −100
HR 10 bool bit 0 RW
HR 11 uint16 RW °C ×0.1 −100
HR 12 uint16 RW °C ×0.1 −100
HR 13 uint16 RW °C ×0.1 −100
HR 14 uint16 RW °C ×0.1 −100
HR 16 uint16 RW °C ×0.1 −100
HR 17 uint16 RW °C ×0.1 −100
HR 18 uint16 RW °C ×0.1 −100
HR 19 uint16 RW °C ×0.1 −100
HR 21 uint16 RW °C ×0.1 −100
HR 22 uint16 RW °C ×0.1 −100
HR 23 uint16 RW °C ×0.1 −100
HR 24 uint16 RW °C ×0.1 −100
HR 25 uint16 RW Range 0 to 100; the scale column in the document is not clear, so the value is raw
HR 26 uint16 RW Range 0 to 100; the scale column in the document is not clear, so the value is raw
HR 27 uint16 RW min
HR 28 uint16 RW ×0.1 Winding-to-oil gradient setting; the document gives no unit
HR 29 uint16 RW ×0.1 Winding-to-oil gradient setting; the document gives no unit
HR 30 uint16 RW ×0.1 Winding-to-oil gradient setting; the document gives no unit
HR 31 uint16 RW Range 0 to 300; the document gives no unit
HR 32 uint16 RW Range 0 to 300; the document gives no unit
HR 33 uint16 RW Range 0 to 300; the document gives no unit
HR 34 uint16 RW ×0.1
HR 35 uint16 RW ×0.1
HR 36 uint16 RW ×0.1
HR 37 uint16 RW Range 1 to 9999; the document's scale column (1000:10) is not clear, so the value is raw
HR 38 uint16 RW Range 1 to 9999; the document's scale column (1000:10) is not clear, so the value is raw
HR 39 uint16 RW Range 1 to 9999; the document's scale column (1000:10) is not clear, so the value is raw
HR 40 uint16 RW
HR 41 uint16 RW
HR 42 uint16 RW
HR 43 uint16 RW
HR 44 uint16 RW The document labels every value "when 0"; the value is the index of the range
HR 45 bool bit 0 W Write 1
HR 45 bool bit 1 W Write 1
HR 45 bool bit 2 W Write 1
HR 45 bool bit 3 W Write 1
HR 45 bool bit 4 W Write 1
HR 45 bool bit 5 W Write 1
HR 48 bool bit 0 RW 0 = automatic, 1 = forced on
HR 48 bool bit 1 RW 0 = automatic, 1 = forced on
HR 48 bool bit 2 RW 0 = automatic, 1 = forced on
HR 50 bool bit 0 RW The document does not explain BKP and INDP
HR 51 uint16 RW ×0.1
HR 52 bool bit 2 RW
HR 52 bool bit 3 RW
HR 52 bool bit 4 RW
HR 53 uint16 R °C ×0.1 −100 Document label: current temperature of sensor 1
HR 54 uint16 R °C ×0.1 −100
HR 55 uint16 R °C ×0.1 −100
HR 56 uint16 R °C ×0.1 −100
HR 57 uint16 R °C ×0.1 −100
HR 58 uint16 R °C ×0.1 −100
HR 59 uint16 R °C ×0.1 −100
HR 60 uint16 R °C ×0.1 −100
HR 61 uint16 R °C ×0.1 −100
HR 62 uint16 R °C ×0.1 −100
HR 63 uint16 R ×0.1
HR 64 uint16 R ×0.1
HR 65 uint16 R ×0.1
HR 66 uint16 R % ×0.1
HR 67 uint16 R % ×0.1
HR 68 uint16 R % ×0.1
HR 69 uint16 R A ×0.01
HR 70 uint16 R A ×0.01
HR 71 uint16 R A ×0.01
HR 72 uint16 R A ×0.01
HR 73 uint16 R A ×0.01
HR 74 uint16 R A ×0.01
HR 75 bool bit 0 RW
HR 75 bool bit 1 RW
HR 75 bool bit 2 RW
HR 75 bool bit 3 RW
HR 75 bool bit 4 RW
HR 75 bool bit 5 RW
HR 75 bool bit 6 RW
HR 75 bool bit 7 RW
HR 75 bool bit 8 RW
HR 75 bool bit 9 RW
HR 75 bool bit 10 RW
HR 77 uint16 RW ×0.1
HR 78 uint16 RW
HR 79 bool bit 0 RW 0 = automatic reset, 1 = manual reset
HR 79 bool bit 1 RW 0 = automatic reset, 1 = manual reset
HR 79 bool bit 2 RW 0 = automatic reset, 1 = manual reset
HR 79 bool bit 3 RW 0 = automatic reset, 1 = manual reset
HR 79 bool bit 4 RW 0 = automatic reset, 1 = manual reset
HR 79 bool bit 5 RW 0 = automatic reset, 1 = manual reset
HR 79 bool bit 6 RW 0 = automatic reset, 1 = manual reset
HR 79 bool bit 7 RW 0 = automatic reset, 1 = manual reset
HR 79 bool bit 8 RW 0 = automatic reset, 1 = manual reset

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