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Seneca S203T Modbus register map

Seneca S203T three-phase network analyzer with RS-485 Modbus RTU and analog retransmission

  • Official
  • 65 registers
  • Modbus RTU
  • Revision 2 · 2026-10-17

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
38400 8N1 · 38400 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
65 holding registers
Groups
7
Revision
2 · 2026-10-17
Added
()
File
maps/seneca/s203.mbmap.json · 12 KB · history
SHA-256
9c7eb92feaa337de4a5fc030f0c9908374bf9ca5471e43784fd725a3f20af135
Manufacturer
seneca.it

Sources and notes

Source: Seneca, "S203T Advanced Three-phase Network Analyzer" user manual, MI001266-E

  • All registers are holding registers: FC03 reads and FC06/FC16 writes, at most 16 registers at a time within the same group.
  • Addresses are the manual's register numbers minus 40000, with address_base 1 (register 40135 is address 135).
  • Floats are two registers, most significant word first. Currents are in mA.
  • Defaults: address 1, 38400 baud, no parity.
  • The CT ratio (40026) scales the float currents, powers and energies, not the normalised (0-10000) values.
AreaAddressNameTypeAccessUnitScaleDescription
HR 1 uint16 R High byte: module ID (26); low byte: firmware revision
HR 24 uint16 RW Default 0
HR 25 uint16 RW 0 phase A, 1 phase B, 2 phase C, any other value three-phase
HR 26 float32 ABCD RW A Default 1000.0
HR 28 float32 ABCD RW Value of the retransmitted quantity giving 0 % output, in its unit (V, mA or W). Default 0.0
HR 30 float32 ABCD RW Value giving 100 % output. Default 600.0
HR 32 uint16 RW Corrects power and energy when the line frequency is unstable
HR 33 uint16 RW High byte: address 0-255 (default 1); low byte: parity 0 none (default), 1 even, 2 odd
HR 34 uint16 RW High byte: 0 4800, 1 9600, 2 19200, 3 38400 (default), 4 57600, 5 115200, 6 1200, 7 2400; low byte: response delay in pauses of 6 characters (default 0)
HR 131 uint16 W 0x1000 resets the active energy of all phases; 0x1234 restarts
HR 133 uint16 R Bit 15: error saving energy; bit 6: phases B and C reversed; bits 3-5: voltage on A, B, C above 40 V
HR 135 float32 ABCD R V
HR 137 float32 ABCD R V
HR 139 float32 ABCD R V
HR 141 float32 ABCD R V
HR 143 float32 ABCD R mA
HR 145 float32 ABCD R mA
HR 147 float32 ABCD R mA
HR 149 float32 ABCD R mA
HR 151 float32 ABCD R W
HR 153 float32 ABCD R W
HR 155 float32 ABCD R W
HR 157 float32 ABCD R W
HR 159 float32 ABCD R var
HR 161 float32 ABCD R var
HR 163 float32 ABCD R var
HR 165 float32 ABCD R var
HR 167 float32 ABCD R VA
HR 169 float32 ABCD R VA
HR 171 float32 ABCD R VA
HR 173 float32 ABCD R VA
HR 175 float32 ABCD R
HR 177 float32 ABCD R
HR 179 float32 ABCD R
HR 181 float32 ABCD R
HR 183 float32 ABCD R Hz
HR 185 float32 ABCD R Wh
HR 187 float32 ABCD R Wh
HR 189 float32 ABCD R Wh
HR 191 float32 ABCD R Wh
HR 193 uint16 R 0 to 10000
HR 194 uint16 R 0 to 10000
HR 195 uint16 R 0 to 10000
HR 196 uint16 R 0 to 10000
HR 197 uint16 R 0 to 10000
HR 198 uint16 R 0 to 10000
HR 199 uint16 R 0 to 10000
HR 200 uint16 R 0 to 10000
HR 201 uint16 R 0 to 10000
HR 202 uint16 R 0 to 10000
HR 203 uint16 R 0 to 10000
HR 204 uint16 R 0 to 10000
HR 205 int16 R -10000 to +10000
HR 206 int16 R -10000 to +10000
HR 207 int16 R -10000 to +10000
HR 208 int16 R -10000 to +10000
HR 209 uint16 R 0 to 10000
HR 210 uint16 R 0 to 10000
HR 211 uint16 R 0 to 10000
HR 212 uint16 R 0 to 10000
HR 213 int16 R -10000 to +10000
HR 214 int16 R -10000 to +10000
HR 215 int16 R -10000 to +10000
HR 216 int16 R -10000 to +10000
HR 217 uint16 R 0-10000 between the retransmission minimum and maximum, saturating at 11000

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